Implement s4u extensions

Merge Luke's users/lhoward/s4u branch to trunk.  Implements S4U2Self
and S4U2Proxy extensions.

ticket: 6563

git-svn-id: svn://anonsvn.mit.edu/krb5/trunk@22736 dc483132-0cff-0310-8789-dd5450dbe970

71 files changed, 5306 insertions, 576 deletions

diff --git a/src/clients/kvno/kvno.M b/src/clients/kvno/kvno.M
index b7e4d46a0..37b0bcbd5 100644
--- a/src/clients/kvno/kvno.M
+++ b/src/clients/kvno/kvno.M
@@ -51,6 +51,13 @@ suppress printing
 .B \-h
 prints a usage statement and exits
 .TP
+.B \-P
+specifies that the
+.B service1 service2 ...
+arguments are to be treated as services for which credentials should
+be acquired using constrained delegation. This option is only valid
+when used in conjunction with protocol transition.
+.TP
 .B \-S sname
 specifies that krb5_sname_to_principal() will be used to build
 principal names.  If this flag is specified, the
@@ -59,6 +66,13 @@ arguments are interpreted as hostnames (rather than principal names),
 and
 .B sname
 is interpreted as the service name.
+.TP
+.B \-U for_user
+specifies that protocol transition (S4U2Self) is to be used to acquire
+a ticket on behalf of
+.B for_user.
+If constrained delegation is not requested, the service name
+must match the credentials cache client principal.
 .SH ENVIRONMENT
 .B Kvno
 uses the following environment variable:
diff --git a/src/clients/kvno/kvno.c b/src/clients/kvno/kvno.c
index b98b85d30..58702525f 100644
--- a/src/clients/kvno/kvno.c
+++ b/src/clients/kvno/kvno.c
@@ -39,8 +39,9 @@ static char *prog;
 
 static void xusage()
 {
-    fprintf(stderr, "usage: %s [-C] [-u] [-c ccache] [-e etype] [-k keytab] [-S sname] service1 service2 ...\n",
-            prog);
+    fprintf(stderr, "usage: %s [-C] [-u] [-c ccache] [-e etype]\n", prog);
+    fprintf(stderr, "\t[-k keytab] [-S sname] [-U for_user [-P]]\n");
+    fprintf(stderr, "\tservice1 service2 ...\n");
     exit(1);
 }
 
@@ -48,7 +49,8 @@ int quiet = 0;
 
 static void do_v5_kvno (int argc, char *argv[], 
                         char *ccachestr, char *etypestr, char *keytab_name,
-			char *sname, int canon, int unknown);
+			char *sname, int canon, int unknown,
+			char *for_user, int proxy);
 
 #include <com_err.h>
 static void extended_com_err_fn (const char *, errcode_t, const char *,
@@ -58,8 +60,8 @@ int main(int argc, char *argv[])
 {
     int option;
     char *etypestr = NULL, *ccachestr = NULL, *keytab_name = NULL;
-    char *sname = NULL;
-    int canon = 0, unknown = 0;
+    char *sname = NULL, *for_user = NULL;
+    int canon = 0, unknown = 0, proxy = 0;
 
 
     set_com_err_hook (extended_com_err_fn);
@@ -67,7 +69,7 @@ int main(int argc, char *argv[])
     prog = strrchr(argv[0], '/');
     prog = prog ? (prog + 1) : argv[0];
 
-    while ((option = getopt(argc, argv, "uCc:e:hk:qS:")) != -1) {
+    while ((option = getopt(argc, argv, "uCc:e:hk:qPS:U:")) != -1) {
 	switch (option) {
 	case 'C':
 	    canon = 1;
@@ -87,6 +89,9 @@ int main(int argc, char *argv[])
 	case 'q':
 	    quiet = 1;
 	    break;
+	case 'P':
+	    proxy = 1; /* S4U2Proxy - constrained delegation */
+	    break;
 	case 'S':
 	    sname = optarg;
             if (unknown == 1){ 
@@ -101,21 +106,37 @@ int main(int argc, char *argv[])
 	        xusage();
             }
             break;
+	case 'U':
+	    for_user = optarg; /* S4U2Self - protocol transition */
+	    break;
 	default:
 	    xusage();
 	    break;
 	}
     }
 
+    if (proxy) {
+	if (keytab_name == NULL) {
+	    fprintf(stderr, "Option -P (constrained delegation) "
+			    "requires keytab to be specified\n");
+	    xusage();
+	} else if (for_user == NULL) {
+	    fprintf(stderr, "Option -P (constrained delegation) requires "
+			    "option -U (protocol transition)\n");
+	    xusage();
+	}
+    }
+
     if ((argc - optind) < 1)
 	xusage();
 
 	do_v5_kvno(argc - optind, argv + optind,
-		   ccachestr, etypestr, keytab_name, sname, canon, unknown);
+		   ccachestr, etypestr, keytab_name, sname,
+		   canon, unknown, for_user, proxy);
     return 0;
 }
 
-#include <krb5.h>
+#include <k5-int.h>
 static krb5_context context;
 static void extended_com_err_fn (const char *myprog, errcode_t code,
 				 const char *fmt, va_list args)
@@ -130,17 +151,18 @@ static void extended_com_err_fn (const char *myprog, errcode_t code,
 
 static void do_v5_kvno (int count, char *names[], 
                         char * ccachestr, char *etypestr, char *keytab_name,
-			char *sname, int canon, int unknown)
+			char *sname, int canon, int unknown, char *for_user,
+			int proxy)
 {
     krb5_error_code ret;
     int i, errors;
     krb5_enctype etype;
     krb5_ccache ccache;
     krb5_principal me;
-    krb5_creds in_creds, *out_creds;
-    krb5_ticket *ticket;
-    char *princ;
+    krb5_creds in_creds;
     krb5_keytab keytab = NULL;
+    krb5_principal for_user_princ = NULL;
+    krb5_flags options;
 
     ret = krb5_init_context(&context);
     if (ret) {
@@ -175,6 +197,16 @@ static void do_v5_kvno (int count, char *names[],
 	}
     }
 
+    if (for_user) {
+	ret = krb5_parse_name_flags(context, for_user,
+				    KRB5_PRINCIPAL_PARSE_ENTERPRISE,
+				    &for_user_princ);
+	if (ret) {
+	    com_err(prog, ret, "while parsing principal name %s", for_user);
+	    exit(1);
+	}
+    }
+
     ret = krb5_cc_get_principal(context, ccache, &me);
     if (ret) {
 	com_err(prog, ret, "while getting client principal name");
@@ -183,91 +215,131 @@ static void do_v5_kvno (int count, char *names[],
 
     errors = 0;
 
+    options = 0;
+    if (canon)
+	options |= KRB5_GC_CANONICALIZE;
+
     for (i = 0; i < count; i++) {
-	memset(&in_creds, 0, sizeof(in_creds));
+	krb5_principal server = NULL;
+	krb5_ticket *ticket = NULL;
+	krb5_creds *out_creds = NULL;
+	char *princ = NULL;
 
-	in_creds.client = me;
+	memset(&in_creds, 0, sizeof(in_creds));
 
 	if (sname != NULL) {
 	    ret = krb5_sname_to_principal(context, names[i],
 					  sname, KRB5_NT_SRV_HST,
-					  &in_creds.server);
+					  &server);
 	} else {
-	    ret = krb5_parse_name(context, names[i], &in_creds.server);
+	    ret = krb5_parse_name(context, names[i], &server);
 	}
 	if (ret) {
 	    if (!quiet)
 		com_err(prog, ret, "while parsing principal name %s", names[i]);
-	    errors++;
-	    continue;
+	    goto error;
 	}
         if (unknown == 1) {
-            krb5_princ_type(context, in_creds.server) = KRB5_NT_UNKNOWN;
+            krb5_princ_type(context, server) = KRB5_NT_UNKNOWN;
         }
 
-	ret = krb5_unparse_name(context, in_creds.server, &princ);
+	ret = krb5_unparse_name(context, server, &princ);
 	if (ret) {
 	    com_err(prog, ret,
 		    "while formatting parsed principal name for '%s'",
 		    names[i]);
-	    errors++;
-	    continue;
+	    goto error;
 	}
 
 	in_creds.keyblock.enctype = etype;
 
-	ret = krb5_get_credentials(context, canon ? KRB5_GC_CANONICALIZE : 0,
-				   ccache, &in_creds, &out_creds);
+	if (for_user) {
+	    if (!proxy &&
+		!krb5_principal_compare(context, me, server)) {
+		com_err(prog, EINVAL,
+			"client and server principal names must match");
+		goto error;
+	    }
 
-	krb5_free_principal(context, in_creds.server);
+	    in_creds.client = for_user_princ;
+	    in_creds.server = me;
+
+	    ret = krb5_get_credentials_for_user(context, options, ccache,
+						&in_creds, NULL, &out_creds);
+	} else {
+	    in_creds.client = me;
+	    in_creds.server = server;
+	    ret = krb5_get_credentials(context, options, ccache,
+				       &in_creds, &out_creds);
+	}
 
 	if (ret) {
 	    com_err(prog, ret, "while getting credentials for %s", princ);
-
-	    krb5_free_unparsed_name(context, princ);
-
-	    errors++;
-	    continue;
+	    goto error;
 	}
 
 	/* we need a native ticket */
 	ret = krb5_decode_ticket(&out_creds->ticket, &ticket);
 	if (ret) {
 	    com_err(prog, ret, "while decoding ticket for %s", princ);
-	    krb5_free_creds(context, out_creds);
-	    krb5_free_unparsed_name(context, princ);
-
-	    errors++;
-	    continue;
+	    goto error;
 	}
-	    
+
 	if (keytab) {
 	    ret = krb5_server_decrypt_ticket_keytab(context, keytab, ticket);
 	    if (ret) {
-		if (!quiet)
-		    printf("%s: kvno = %d, keytab entry invalid", princ, ticket->enc_part.kvno);
+		if (!quiet) {
+		    fprintf(stderr, "%s: kvno = %d, keytab entry invalid\n",
+			    princ, ticket->enc_part.kvno);
+		}
 		com_err(prog, ret, "while decrypting ticket for %s", princ);
-		krb5_free_ticket(context, ticket);
-		krb5_free_creds(context, out_creds);
-		krb5_free_unparsed_name(context, princ);
-
-		errors++;
-		continue;
+		goto error;
 	    }
 	    if (!quiet)
-		printf("%s: kvno = %d, keytab entry valid\n", princ, ticket->enc_part.kvno);
+		printf("%s: kvno = %d, keytab entry valid\n",
+		       princ, ticket->enc_part.kvno);
+	    if (proxy) {
+		krb5_free_creds(context, out_creds);
+		out_creds = NULL;
+
+		in_creds.client = ticket->enc_part2->client;
+		in_creds.server = server;
+
+		ret = krb5_get_credentials_for_proxy(context,
+						     KRB5_GC_CANONICALIZE,
+						     ccache,
+						     &in_creds,
+						     ticket,
+						     &out_creds);
+		if (ret) {
+		    com_err(prog, ret,
+			    "%s: constrained delegation failed", princ);
+		    goto error;
+		}
+	    }
 	} else {
 	    if (!quiet)
 		printf("%s: kvno = %d\n", princ, ticket->enc_part.kvno);
 	}
 
-	krb5_free_creds(context, out_creds);
-	krb5_free_unparsed_name(context, princ);
+	continue;
+
+error:
+	if (server != NULL)
+	    krb5_free_principal(context, server);
+	if (ticket != NULL)
+	    krb5_free_ticket(context, ticket);
+	if (out_creds != NULL)
+	    krb5_free_creds(context, out_creds);
+	if (princ != NULL)
+	    krb5_free_unparsed_name(context, princ);
+	errors++;
     }
 
     if (keytab)
 	krb5_kt_close(context, keytab);
     krb5_free_principal(context, me);
+    krb5_free_principal(context, for_user_princ);
     krb5_cc_close(context, ccache);
     krb5_free_context(context);
 
diff --git a/src/include/k5-int.h b/src/include/k5-int.h
index 90b6d9cf7..dbe522356 100644
--- a/src/include/k5-int.h
+++ b/src/include/k5-int.h
@@ -966,6 +966,21 @@ typedef struct _krb5_pa_for_user {
     krb5_data		auth_package;
 } krb5_pa_for_user;
 
+typedef struct _krb5_s4u_userid {
+    krb5_int32		nonce;
+    krb5_principal	user;
+    krb5_data		subject_cert;
+    krb5_flags		options;
+} krb5_s4u_userid;
+
+#define KRB5_S4U_OPTS_CHECK_LOGON_HOURS		0x40000000 /* check logon hour restrictions */
+#define KRB5_S4U_OPTS_USE_REPLY_KEY_USAGE	0x20000000 /* sign with usage 27 instead of 26 */
+
+typedef struct _krb5_pa_s4u_x509_user {
+    krb5_s4u_userid	user_id;
+    krb5_checksum	cksum;
+} krb5_pa_s4u_x509_user;
+
 enum {
   KRB5_FAST_ARMOR_AP_REQUEST = 0x1
 };
@@ -1295,6 +1310,10 @@ void KRB5_CALLCONV krb5_free_pa_enc_ts
 	(krb5_context, krb5_pa_enc_ts *);
 void KRB5_CALLCONV krb5_free_pa_for_user
 	(krb5_context, krb5_pa_for_user * );
+void KRB5_CALLCONV krb5_free_s4u_userid_contents
+	(krb5_context, krb5_s4u_userid * );
+void KRB5_CALLCONV krb5_free_pa_s4u_x509_user
+	(krb5_context, krb5_pa_s4u_x509_user * );
 void KRB5_CALLCONV krb5_free_pa_svr_referral_data
 	(krb5_context, krb5_pa_svr_referral_data * );
 void KRB5_CALLCONV krb5_free_pa_server_referral_data
@@ -1609,6 +1628,12 @@ krb5_error_code encode_krb5_setpw_req
 krb5_error_code encode_krb5_pa_for_user
 	(const krb5_pa_for_user * , krb5_data **);
 
+krb5_error_code encode_krb5_s4u_userid
+	(const krb5_s4u_userid * , krb5_data **);
+
+krb5_error_code encode_krb5_pa_s4u_x509_user
+	(const krb5_pa_s4u_x509_user * , krb5_data **);
+
 krb5_error_code encode_krb5_pa_svr_referral_data
 	(const krb5_pa_svr_referral_data * , krb5_data **);
 
@@ -1778,6 +1803,9 @@ krb5_error_code decode_krb5_setpw_req
 krb5_error_code decode_krb5_pa_for_user
 	(const krb5_data *, krb5_pa_for_user **);
 
+krb5_error_code decode_krb5_pa_s4u_x509_user
+	(const krb5_data *, krb5_pa_s4u_x509_user **);
+
 krb5_error_code decode_krb5_pa_svr_referral_data
 	(const krb5_data *, krb5_pa_svr_referral_data **);
 
@@ -2606,6 +2634,11 @@ krb5_error_code krb5int_send_tgs
 		krb5_pa_data * const *,
 		const krb5_data *,
 		krb5_creds *,
+		krb5_error_code (*gcvt_fct)(krb5_context,
+					    krb5_keyblock *,
+					    krb5_kdc_req *,
+					    void *),
+		void *gcvt_data,
 		krb5_response * , krb5_keyblock **subkey);
                 /* The subkey field is an output parameter; if a
 		 * tgs-rep is received then the subkey will be filled
@@ -2796,6 +2829,21 @@ krb5int_pac_sign(krb5_context context,
 		 const krb5_keyblock *privsvr_key,
 		 krb5_data *data);
 
+krb5_error_code KRB5_CALLCONV
+krb5_get_credentials_for_user(krb5_context context, krb5_flags options,
+			      krb5_ccache ccache,
+			      krb5_creds *in_creds,
+			      krb5_data *cert,
+			      krb5_creds **out_creds);
+
+krb5_error_code KRB5_CALLCONV
+krb5_get_credentials_for_proxy(krb5_context context,
+			       krb5_flags options,
+			       krb5_ccache ccache,
+			       krb5_creds *in_creds,
+			       krb5_ticket *evidence_tkt,
+			       krb5_creds **out_creds);
+
 krb5_error_code krb5int_parse_enctype_list(krb5_context context, char *profstr,
 					   krb5_enctype *default_list,
 					   krb5_enctype **result);
diff --git a/src/include/kdb.h b/src/include/kdb.h
index ea81cfeef..8c0cd247a 100644
--- a/src/include/kdb.h
+++ b/src/include/kdb.h
@@ -96,6 +96,8 @@
 #define KRB5_KDB_SUPPORT_DESMD5         0x00004000
 #define	KRB5_KDB_NEW_PRINC		0x00008000
 #define KRB5_KDB_OK_AS_DELEGATE		0x00100000
+#define KRB5_KDB_OK_TO_AUTH_AS_DELEGATE	0x00200000 /* S4U2Self OK */
+#define KRB5_KDB_NO_AUTH_DATA_REQUIRED	0x00400000
 
 /* Creation flags */
 #define KRB5_KDB_CREATE_BTREE		0x00000001
diff --git a/src/include/kdb_ext.h b/src/include/kdb_ext.h
index 59323e232..348be5127 100644
--- a/src/include/kdb_ext.h
+++ b/src/include/kdb_ext.h
@@ -31,10 +31,6 @@
 #ifndef KRB5_KDB5_EXT__
 #define KRB5_KDB5_EXT__
 
-/* Allowed to use protocol transition */
-#define KRB5_KDB_OK_TO_AUTH_AS_DELEGATE	0x00200000
-/* Service does not require authorization data */
-#define KRB5_KDB_NO_AUTH_DATA_REQUIRED	0x00400000
 /* Private flag used to indicate principal is local TGS */
 #define KRB5_KDB_TICKET_GRANTING_SERVICE	0x01000000
 /* Private flag used to indicate xrealm relationship  is non-transitive */
diff --git a/src/include/krb5/krb5.hin b/src/include/krb5/krb5.hin
index bf8c29c59..8111c5bb6 100644
--- a/src/include/krb5/krb5.hin
+++ b/src/include/krb5/krb5.hin
@@ -631,6 +631,11 @@ krb5_error_code KRB5_CALLCONV
 
 /* Defined in KDC referrals draft */
 #define KRB5_KEYUSAGE_PA_REFERRAL		26 /* XXX note conflict with above */
+
+/* Defined in [MS-SFU] */
+#define KRB5_KEYUSAGE_PA_S4U_X509_USER_REQUEST	26 /* XXX note conflict with above */
+#define KRB5_KEYUSAGE_PA_S4U_X509_USER_REPLY	27 /* XXX note conflict with above */
+
 /* define in draft-ietf-krb-wg-preauth-framework*/
 #define KRB5_KEYUSAGE_FAST_REQ_CHKSUM 50
 #define KRB5_KEYUSAGE_FAST_ENC 51
@@ -1566,6 +1571,10 @@ void KRB5_CALLCONV krb5_free_tgt_creds
 #define	KRB5_GC_USER_USER	1	/* want user-user ticket */
 #define	KRB5_GC_CACHED		2	/* want cached ticket only */
 #define	KRB5_GC_CANONICALIZE	4	/* set canonicalize KDC option */
+#define	KRB5_GC_NO_STORE	8	/* do not store in credentials cache */
+#define	KRB5_GC_FORWARDABLE		16  /* acquire forwardable tickets */
+#define	KRB5_GC_NO_TRANSIT_CHECK	32  /* disable transited check */
+#define	KRB5_GC_CONSTRAINED_DELEGATION	64  /* constrained delegation */
 
 krb5_error_code KRB5_CALLCONV krb5_get_credentials
 	(krb5_context,
diff --git a/src/kadmin/cli/kadmin.c b/src/kadmin/cli/kadmin.c
index 814ace35c..513e716bb 100644
--- a/src/kadmin/cli/kadmin.c
+++ b/src/kadmin/cli/kadmin.c
@@ -72,7 +72,9 @@ static struct pflag flags[] = {
 {"allow_svr", 9,	KRB5_KDB_DISALLOW_SVR, 1},
 {"password_changing_service",	25,	KRB5_KDB_PWCHANGE_SERVICE,	0 },
 {"support_desmd5",	14,	KRB5_KDB_SUPPORT_DESMD5,	0 },
-{"ok_as_delegate",	14,	KRB5_KDB_OK_AS_DELEGATE,	0 }
+{"ok_as_delegate",	14,	KRB5_KDB_OK_AS_DELEGATE,	0 },
+{"ok_to_auth_as_delegate", 22,	KRB5_KDB_OK_TO_AUTH_AS_DELEGATE, 0 },
+{"no_auth_data_required", 21,	KRB5_KDB_NO_AUTH_DATA_REQUIRED, 0},
 };
 
 static char *prflags[] = {
@@ -97,6 +99,8 @@ static char *prflags[] = {
     "UNKNOWN_0x00040000",	/* 0x00040000 */
     "UNKNOWN_0x00080000",	/* 0x00080000 */
     "OK_AS_DELEGATE",		/* 0x00100000 */
+    "OK_TO_AUTH_AS_DELEGATE",	/* 0x00200000 */
+    "NO_AUTH_DATA_REQUIRED",	/* 0x00400000 */
 };
 
 char *getenv();
@@ -1123,7 +1127,7 @@ kadmin_addprinc_usage(func)
 	    "\t\tallow_postdated allow_forwardable allow_tgs_req allow_renewable\n",
 	    "\t\tallow_proxiable allow_dup_skey allow_tix requires_preauth\n",
 	    "\t\trequires_hwauth needchange allow_svr password_changing_service\n"
-	    "\t\tok_as_delegate\n"
+	    "\t\tok_as_delegate ok_to_auth_as_delegate no_auth_data_required\n"
 	    "\nwhere,\n\t[-x db_princ_args]* - any number of database specific arguments.\n"
 	    "\t\t\tLook at each database documentation for supported arguments\n");
 }
@@ -1140,7 +1144,7 @@ kadmin_modprinc_usage(func)
 	    "\t\tallow_postdated allow_forwardable allow_tgs_req allow_renewable\n",
 	    "\t\tallow_proxiable allow_dup_skey allow_tix requires_preauth\n",
 	    "\t\trequires_hwauth needchange allow_svr password_changing_service\n"
-	    "\t\tok_as_delegate\n"
+	    "\t\tok_as_delegate ok_to_auth_as_delegate no_auth_data_required\n"
 	    "\nwhere,\n\t[-x db_princ_args]* - any number of database specific arguments.\n"
 	    "\t\t\tLook at each database documentation for supported arguments\n"
 	);
diff --git a/src/kdc/do_tgs_req.c b/src/kdc/do_tgs_req.c
index a99dc35ba..37a69e10d 100644
--- a/src/kdc/do_tgs_req.c
+++ b/src/kdc/do_tgs_req.c
@@ -117,7 +117,7 @@ process_tgs_req(krb5_data *pkt, const krb5_fulladdr *from,
     krb5_enc_tkt_part *header_enc_tkt = NULL; /* ticket granting or evidence ticket */
     krb5_db_entry client, krbtgt;
     int c_nprincs = 0, k_nprincs = 0;
-    krb5_pa_for_user *for_user = NULL;           /* protocol transition request */
+    krb5_pa_s4u_x509_user *s4u_x509_user = NULL; /* protocol transition request */
     krb5_authdata **kdc_issued_auth_data = NULL; /* auth data issued by KDC */
     unsigned int c_flags = 0, s_flags = 0;       /* client/server KDB flags */
     char *s4u_name = NULL;
@@ -131,7 +131,7 @@ process_tgs_req(krb5_data *pkt, const krb5_fulladdr *from,
     krb5_data scratch;
 
     session_key.contents = NULL;
-    
+
     retval = decode_krb5_tgs_req(pkt, &request);
     if (retval)
         return retval;
@@ -292,12 +292,20 @@ tgt_again:
         !krb5_principal_compare(kdc_context, tgs_server, server.princ);
 
     /* Check for protocol transition */
-    errcode = kdc_process_s4u2self_req(kdc_context, request, header_enc_tkt->client,
-                                       &server, header_enc_tkt->session, kdc_time,
-                                       &for_user, &client, &c_nprincs, &status);
+    errcode = kdc_process_s4u2self_req(kdc_context,
+				       request,
+				       header_enc_tkt->client,
+                                       &server,
+				       subkey,
+				       header_enc_tkt->session,
+				       kdc_time,
+                                       &s4u_x509_user,
+				       &client,
+				       &c_nprincs,
+				       &status);
     if (errcode)
         goto cleanup;
-    if (for_user != NULL)
+    if (s4u_x509_user != NULL)
         setflag(c_flags, KRB5_KDB_FLAG_PROTOCOL_TRANSITION);
 
     /*
@@ -438,19 +446,32 @@ tgt_again:
     /* processing of any of these flags.  For example, some */
     /* realms may refuse to issue renewable tickets         */
 
-    if (isflagset(request->kdc_options, KDC_OPT_FORWARDABLE))
+    if (isflagset(request->kdc_options, KDC_OPT_FORWARDABLE)) {
         setflag(enc_tkt_reply.flags, TKT_FLG_FORWARDABLE);
-    if (isflagset(c_flags, KRB5_KDB_FLAG_PROTOCOL_TRANSITION)) {
-        if (!krb5_is_tgs_principal(server.princ) &&
-            is_local_principal(server.princ)) {
-            if (isflagset(server.attributes, KRB5_KDB_OK_TO_AUTH_AS_DELEGATE))
-                setflag(enc_tkt_reply.flags, TKT_FLG_FORWARDABLE);
-            else
+
+        if (isflagset(c_flags, KRB5_KDB_FLAG_PROTOCOL_TRANSITION)) {
+            /*
+             * If S4U2Self principal is not forwardable, then mark ticket as
+             * unforwardable. This behaviour matches Windows, but it is
+             * different to the MIT AS-REQ path, which returns an error
+             * (KDC_ERR_POLICY) if forwardable tickets cannot be issued.
+             *
+             * Consider this block the S4U2Self equivalent to
+             * validate_forwardable().
+             */
+            if (c_nprincs &&
+                isflagset(client.attributes, KRB5_KDB_DISALLOW_FORWARDABLE))
+                clear(enc_tkt_reply.flags, TKT_FLG_FORWARDABLE);
+            /*
+             * OK_TO_AUTH_AS_DELEGATE must be set on the service requesting
+             * S4U2Self in order for forwardable tickets to be returned.
+             */
+            else if (!is_referral &&
+                !isflagset(server.attributes, KRB5_KDB_OK_TO_AUTH_AS_DELEGATE))
                 clear(enc_tkt_reply.flags, TKT_FLG_FORWARDABLE);
         }
-        if (isflagset(client.attributes, KRB5_KDB_DISALLOW_FORWARDABLE))
-            clear(enc_tkt_reply.flags, TKT_FLG_FORWARDABLE);
     }
+
     if (isflagset(request->kdc_options, KDC_OPT_FORWARDED)) {
         setflag(enc_tkt_reply.flags, TKT_FLG_FORWARDED);
 
@@ -560,7 +581,7 @@ tgt_again:
         enc_tkt_reply.times.starttime = 0;
 
     if (isflagset(c_flags, KRB5_KDB_FLAG_PROTOCOL_TRANSITION)) {
-        errcode = krb5_unparse_name(kdc_context, for_user->user, &s4u_name);
+        errcode = krb5_unparse_name(kdc_context, s4u_x509_user->user_id.user, &s4u_name);
     } else if (isflagset(c_flags, KRB5_KDB_FLAG_CONSTRAINED_DELEGATION)) {
         errcode = krb5_unparse_name(kdc_context, header_enc_tkt->client, &s4u_name);
     } else {
@@ -670,8 +691,8 @@ tgt_again:
     enc_tkt_reply.authorization_data = NULL;
 
     if (isflagset(c_flags, KRB5_KDB_FLAG_PROTOCOL_TRANSITION) &&
-        is_local_principal(header_enc_tkt->client))
-        enc_tkt_reply.client = for_user->user;
+        !isflagset(c_flags, KRB5_KDB_FLAG_CROSS_REALM))
+        enc_tkt_reply.client = s4u_x509_user->user_id.user;
     else
         enc_tkt_reply.client = header_enc_tkt->client;
 
@@ -685,7 +706,8 @@ tgt_again:
                               &encrypting_key, /* U2U or server key */
                               pkt,
                               request,
-                              for_user ? for_user->user : NULL,
+                              s4u_x509_user ?
+				s4u_x509_user->user_id.user : NULL,
                               header_enc_tkt,
                               &enc_tkt_reply);
     if (errcode) {
@@ -845,6 +867,20 @@ tgt_again:
     /* Start assembling the response */
     reply.msg_type = KRB5_TGS_REP;
     reply.padata = 0;/* always */
+    if (isflagset(c_flags, KRB5_KDB_FLAG_PROTOCOL_TRANSITION) &&
+        find_pa_data(request->padata, KRB5_PADATA_S4U_X509_USER) != NULL) {
+        errcode = kdc_make_s4u2self_rep(kdc_context,
+                                        subkey,
+                                        header_ticket->enc_part2->session,
+                                        s4u_x509_user,
+                                        &reply,
+                                        &reply_encpart);
+        if (errcode) {
+            status = "KDC_RETURN_S4U2SELF_PADATA";
+            goto cleanup;
+        }
+    }
+
     reply.client = enc_tkt_reply.client;
     reply.enc_part.kvno = 0;/* We are using the session key */
     reply.ticket = &ticket_reply;
@@ -958,14 +994,18 @@ cleanup:
         krb5_db_free_principal(kdc_context, &krbtgt, k_nprincs);
     if (c_nprincs)
         krb5_db_free_principal(kdc_context, &client, c_nprincs);
-    if (for_user != NULL)
-        krb5_free_pa_for_user(kdc_context, for_user);
+    if (s4u_x509_user != NULL)
+        krb5_free_pa_s4u_x509_user(kdc_context, s4u_x509_user);
     if (kdc_issued_auth_data != NULL)
         krb5_free_authdata(kdc_context, kdc_issued_auth_data);
     if (s4u_name != NULL)
         free(s4u_name);
     if (subkey != NULL)
         krb5_free_keyblock(kdc_context, subkey);
+    if (reply.padata)
+        krb5_free_pa_data(kdc_context, reply.padata);
+    if (reply_encpart.enc_padata)
+        krb5_free_pa_data(kdc_context, reply_encpart.enc_padata);
 
     return retval;
 }
diff --git a/src/kdc/kdc_authdata.c b/src/kdc/kdc_authdata.c
index 43ea0869a..504d3fbdd 100644
--- a/src/kdc/kdc_authdata.c
+++ b/src/kdc/kdc_authdata.c
@@ -544,9 +544,18 @@ handle_tgt_authdata (krb5_context context,
     }
 
     if (ad_nprincs != 0) {
+	/*
+	 * This code was submitted by Novell; however there is no
+	 * mention in [MS-SFU] of needing to examine the authorization
+	 * data to clear the forwardable flag. My understanding is that
+	 * the state of the forwardable flag is propagated through the
+	 * cross-realm TGTs.
+	 */
+#if 0
 	if (isflagset(flags, KRB5_KDB_FLAG_PROTOCOL_TRANSITION) &&
 	    isflagset(ad_entry.attributes, KRB5_KDB_DISALLOW_FORWARDABLE))
 	    clear(enc_tkt_reply->flags, TKT_FLG_FORWARDABLE);
+#endif
 
 	krb5_db_free_principal(context, &ad_entry, ad_nprincs);
 
diff --git a/src/kdc/kdc_preauth.c b/src/kdc/kdc_preauth.c
index cc7ae34ed..2149fd1ac 100644
--- a/src/kdc/kdc_preauth.c
+++ b/src/kdc/kdc_preauth.c
@@ -1349,25 +1349,6 @@ cleanup:
 }
 
 static krb5_boolean
-enctype_requires_etype_info_2(krb5_enctype enctype)
-{
-    switch(enctype) {
-    case ENCTYPE_DES_CBC_CRC:
-    case ENCTYPE_DES_CBC_MD4:
-    case ENCTYPE_DES_CBC_MD5:
-    case ENCTYPE_DES3_CBC_SHA1:
-    case ENCTYPE_DES3_CBC_RAW:
-    case ENCTYPE_ARCFOUR_HMAC:
-    case ENCTYPE_ARCFOUR_HMAC_EXP :
-	return 0;
-    default:
-	if (krb5_c_valid_enctype(enctype))
-	    return 1;
-	else return 0;
-    }
-}
-
-static krb5_boolean
 request_contains_enctype (krb5_context context,  const krb5_kdc_req *request,
 			  krb5_enctype enctype)
 {
diff --git a/src/kdc/kdc_util.c b/src/kdc/kdc_util.c
index 88ef11062..6ac528953 100644
--- a/src/kdc/kdc_util.c
+++ b/src/kdc/kdc_util.c
@@ -223,7 +223,7 @@ comp_cksum(krb5_context kcontext, krb5_data *source, krb5_ticket *ticket,
 krb5_pa_data *
 find_pa_data(krb5_pa_data **padata, krb5_preauthtype pa_type)
 {
-return krb5int_find_pa_data(kdc_context, padata, pa_type);
+    return krb5int_find_pa_data(kdc_context, padata, pa_type);
 }
 
 krb5_error_code 
@@ -371,7 +371,8 @@ kdc_process_tgs_req(krb5_kdc_req *request, const krb5_fulladdr *from,
     }
 
     /* make sure the client is of proper lineage (see above) */
-    if (foreign_server && !find_pa_data(request->padata, KRB5_PADATA_FOR_USER)) {
+    if (foreign_server &&
+	!find_pa_data(request->padata, KRB5_PADATA_FOR_USER)) {
 	if (is_local_principal((*ticket)->enc_part2->client)) {
 	    /* someone in a foreign realm claiming to be local */
 	    krb5_klog_syslog(LOG_INFO, "PROCESS_TGS: failed lineage check");
@@ -926,7 +927,8 @@ fail:
  * as a com_err error number!
  */
 #define AS_INVALID_OPTIONS (KDC_OPT_FORWARDED | KDC_OPT_PROXY |\
-KDC_OPT_VALIDATE | KDC_OPT_RENEW | KDC_OPT_ENC_TKT_IN_SKEY)
+			    KDC_OPT_VALIDATE | KDC_OPT_RENEW | \
+			    KDC_OPT_ENC_TKT_IN_SKEY | KDC_OPT_CNAME_IN_ADDL_TKT)
 int
 validate_as_request(register krb5_kdc_req *request, krb5_db_entry client,
 		    krb5_db_entry server, krb5_timestamp kdc_time,
@@ -998,17 +1000,9 @@ validate_as_request(register krb5_kdc_req *request, krb5_db_entry client,
      *	   preauthentication data is absent in the request.
      *
      * Hence, this check most be done after the check for preauth
-     * data, and is now performed by validate_forwardable().
+     * data, and is now performed by validate_forwardable() (the
+     * contents of which were previously below).
      */
-#if 0
-    /* Client and server must allow forwardable tickets */
-    if (isflagset(request->kdc_options, KDC_OPT_FORWARDABLE) &&
-	(isflagset(client.attributes, KRB5_KDB_DISALLOW_FORWARDABLE) ||
-	 isflagset(server.attributes, KRB5_KDB_DISALLOW_FORWARDABLE))) {
-	*status = "FORWARDABLE NOT ALLOWED";
-	return(KDC_ERR_POLICY);
-    }
-#endif
     
     /* Client and server must allow renewable tickets */
     if (isflagset(request->kdc_options, KDC_OPT_RENEWABLE) &&
@@ -1793,7 +1787,7 @@ sign_db_authdata (krb5_context context,
 }
 
 static krb5_error_code
-verify_s4u2self_checksum(krb5_context context,
+verify_for_user_checksum(krb5_context context,
 			 krb5_keyblock *key,
 			 krb5_pa_for_user *req)
 {
@@ -1852,7 +1846,7 @@ verify_s4u2self_checksum(krb5_context context,
 				  &valid);
 
     if (code == 0 && valid == FALSE)
-	code = KRB5KRB_AP_ERR_BAD_INTEGRITY;
+	code = KRB5KRB_AP_ERR_MODIFIED;
 
     free(data.data);
 
@@ -1860,55 +1854,246 @@ verify_s4u2self_checksum(krb5_context context,
 }
 
 /*
- * Protocol transition validation code based on AS-REQ
- * validation code
+ * Legacy protocol transition (Windows 2003 and above)
  */
-static int
-validate_s4u2self_request(krb5_kdc_req *request,
-			  const krb5_db_entry *client,
-			  krb5_timestamp kdc_time,
-			  const char **status)
+static krb5_error_code
+kdc_process_for_user(krb5_context context,
+		     krb5_pa_data *pa_data,
+		     krb5_keyblock *tgs_session,
+		     krb5_pa_s4u_x509_user **s4u_x509_user,
+		     const char **status)
 {
-    int				errcode;
-    krb5_db_entry		server = { 0 };
- 
-    /* The client must not be expired */
-    if (client->expiration && client->expiration < kdc_time) {
-	*status = "CLIENT EXPIRED";
-	return KDC_ERR_NAME_EXP;
+    krb5_error_code		code;
+    krb5_pa_for_user		*for_user;
+    krb5_data			req_data;
+
+    req_data.length = pa_data->length;
+    req_data.data = (char *)pa_data->contents;
+
+    code = decode_krb5_pa_for_user(&req_data, &for_user);
+    if (code)
+	return code;
+
+    code = verify_for_user_checksum(context, tgs_session, for_user);
+    if (code) {
+	*status = "INVALID_S4U2SELF_CHECKSUM";
+	krb5_free_pa_for_user(kdc_context, for_user);
+	return code;
     }
 
-    /* The client's password must not be expired, unless the server is
-      a KRB5_KDC_PWCHANGE_SERVICE. */
-    if (client->pw_expiration && client->pw_expiration < kdc_time) {
-	*status = "CLIENT KEY EXPIRED";
-	return KDC_ERR_KEY_EXP;
+    *s4u_x509_user = calloc(1, sizeof(krb5_pa_s4u_x509_user));
+    if (*s4u_x509_user == NULL) {
+	krb5_free_pa_for_user(kdc_context, for_user);
+	return ENOMEM;
     }
 
+    (*s4u_x509_user)->user_id.user = for_user->user;
+    for_user->user = NULL;
+    krb5_free_pa_for_user(context, for_user);
+
+    return 0;
+}
+
+static krb5_error_code
+verify_s4u_x509_user_checksum(krb5_context context,
+			      krb5_keyblock *key,
+			      krb5_data *req_data,
+			      krb5_int32 kdc_req_nonce,
+			      krb5_pa_s4u_x509_user *req)
+{
+    krb5_error_code		code;
+    krb5_data			scratch;
+    krb5_boolean		valid = FALSE;
+
+    if (enctype_requires_etype_info_2(key->enctype) &&
+	!krb5_c_is_keyed_cksum(req->cksum.checksum_type))
+	return KRB5KRB_AP_ERR_INAPP_CKSUM;
+
+    if (req->user_id.nonce != kdc_req_nonce)
+	return KRB5KRB_AP_ERR_MODIFIED;
+
     /*
-     * If the client requires password changing, then return an
-     * error; S4U2Self cannot be used to change a password.
+     * Verify checksum over the encoded userid. If that fails,
+     * re-encode, and verify that. This is similar to the
+     * behaviour in kdc_process_tgs_req().
      */
-    if (isflagset(client->attributes, KRB5_KDB_REQUIRES_PWCHANGE)) {
-	*status = "REQUIRED PWCHANGE";
-	return KDC_ERR_KEY_EXP;
+    if (fetch_asn1_field((unsigned char *)req_data->data, 1, 0, &scratch) < 0)
+	return ASN1_PARSE_ERROR;
+
+    code = krb5_c_verify_checksum(context,
+				  key,
+				  KRB5_KEYUSAGE_PA_S4U_X509_USER_REQUEST,
+				  &scratch,
+				  &req->cksum,
+				  &valid);
+    if (code != 0)
+	return code;
+
+    if (valid == FALSE) {
+	krb5_data *data;
+
+	code = encode_krb5_s4u_userid(&req->user_id, &data);
+	if (code != 0)
+	    return code;
+
+	code = krb5_c_verify_checksum(context,
+				      key,
+				      KRB5_KEYUSAGE_PA_S4U_X509_USER_REQUEST,
+				      data,
+				      &req->cksum,
+				      &valid);
+
+	krb5_free_data(context, data);
+
+	if (code != 0)
+	    return code;
     }
 
-    /* Check to see if client is locked out */
-    if (isflagset(client->attributes, KRB5_KDB_DISALLOW_ALL_TIX)) {
-	*status = "CLIENT LOCKED OUT";
-	return KDC_ERR_C_PRINCIPAL_UNKNOWN;
+    return valid ? 0 : KRB5KRB_AP_ERR_MODIFIED;
+}
+
+/*
+ * New protocol transition request (Windows 2008 and above)
+ */
+static krb5_error_code
+kdc_process_s4u_x509_user(krb5_context context,
+			  krb5_kdc_req *request,
+			  krb5_pa_data *pa_data,
+			  krb5_keyblock *tgs_subkey,
+			  krb5_keyblock *tgs_session,
+			  krb5_pa_s4u_x509_user **s4u_x509_user,
+			  const char **status)
+{
+    krb5_error_code		code;
+    krb5_data			req_data;
+
+    req_data.length = pa_data->length;
+    req_data.data = (char *)pa_data->contents;
+
+    code = decode_krb5_pa_s4u_x509_user(&req_data, s4u_x509_user);
+    if (code)
+	return code;
+
+    code = verify_s4u_x509_user_checksum(context,
+					 tgs_subkey ? tgs_subkey :
+					    tgs_session,
+					 &req_data,
+					 request->nonce, *s4u_x509_user);
+
+    if (code) {
+	*status = "INVALID_S4U2SELF_CHECKSUM";
+	krb5_free_pa_s4u_x509_user(context, *s4u_x509_user);
+	*s4u_x509_user = NULL;
+	return code;
     }
 
+    if (krb5_princ_size(context, (*s4u_x509_user)->user_id.user) == 0 ||
+	(*s4u_x509_user)->user_id.subject_cert.length != 0) {
+	*status = "INVALID_S4U2SELF_REQUEST";
+	krb5_free_pa_s4u_x509_user(context, *s4u_x509_user);
+	*s4u_x509_user = NULL;
+	return KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN;
+    }
+
+    return 0;
+}
+
+krb5_error_code
+kdc_make_s4u2self_rep(krb5_context context,
+		      krb5_keyblock *tgs_subkey,
+		      krb5_keyblock *tgs_session,
+		      krb5_pa_s4u_x509_user *req_s4u_user,
+		      krb5_kdc_rep *reply,
+		      krb5_enc_kdc_rep_part *reply_encpart)
+{
+    krb5_error_code		code;
+    krb5_data			*data = NULL;
+    krb5_pa_s4u_x509_user	rep_s4u_user;
+    krb5_pa_data		padata;
+    krb5_enctype		enctype;
+    krb5_keyusage		usage;
+
+    memset(&rep_s4u_user, 0, sizeof(rep_s4u_user));
+
+    rep_s4u_user.user_id.nonce   = req_s4u_user->user_id.nonce;
+    rep_s4u_user.user_id.user    = req_s4u_user->user_id.user;
+    rep_s4u_user.user_id.options =
+	req_s4u_user->user_id.options & KRB5_S4U_OPTS_USE_REPLY_KEY_USAGE;
+
+    code = encode_krb5_s4u_userid(&rep_s4u_user.user_id, &data);
+    if (code != 0)
+        goto cleanup;
+
+    if (req_s4u_user->user_id.options & KRB5_S4U_OPTS_USE_REPLY_KEY_USAGE)
+        usage = KRB5_KEYUSAGE_PA_S4U_X509_USER_REPLY;
+    else
+        usage = KRB5_KEYUSAGE_PA_S4U_X509_USER_REQUEST;
+
+    code = krb5_c_make_checksum(context, req_s4u_user->cksum.checksum_type,
+				tgs_subkey != NULL ? tgs_subkey : tgs_session,
+                                usage, data,
+                                &rep_s4u_user.cksum);
+    if (code != 0)
+        goto cleanup;
+
+    krb5_free_data(context, data);
+    data = NULL;
+
+    code = encode_krb5_pa_s4u_x509_user(&rep_s4u_user, &data);
+    if (code != 0)
+        goto cleanup;
+
+    padata.magic = KV5M_PA_DATA;
+    padata.pa_type = KRB5_PADATA_S4U_X509_USER;
+    padata.length = data->length;
+    padata.contents = (krb5_octet *)data->data;
+
+    code = add_pa_data_element(context, &padata, &reply->padata, FALSE);
+    if (code != 0)
+	goto cleanup;
+
+    free(data);
+    data = NULL;
+
+    if (tgs_subkey != NULL)
+	enctype = tgs_subkey->enctype;
+    else
+	enctype = tgs_session->enctype;
+
     /*
-     * Check against local policy
+     * Owing to a bug in Windows, unkeyed checksums were used for older
+     * enctypes, including rc4-hmac. A forthcoming workaround for this
+     * includes the checksum bytes in the encrypted padata.
      */
-    errcode = against_local_policy_as(request, *client, server,
-				      kdc_time, status); 
-    if (errcode)
-	return errcode;
+    if ((req_s4u_user->user_id.options & KRB5_S4U_OPTS_USE_REPLY_KEY_USAGE) &&
+	enctype_requires_etype_info_2(enctype) == FALSE) {
+	padata.length = req_s4u_user->cksum.length +
+		        rep_s4u_user.cksum.length;
+	padata.contents = malloc(padata.length);
+	if (padata.contents == NULL) {
+	    code = ENOMEM;
+	    goto cleanup;
+	}
 
-    return 0;
+	memcpy(padata.contents,
+	       req_s4u_user->cksum.contents,
+	       req_s4u_user->cksum.length);
+	memcpy(&padata.contents[req_s4u_user->cksum.length],
+	       rep_s4u_user.cksum.contents,
+	       rep_s4u_user.cksum.length);
+
+	code = add_pa_data_element(context,&padata,
+				   &reply_encpart->enc_padata, FALSE);
+	if (code != 0)
+	    goto cleanup;
+    }
+
+cleanup:
+    if (rep_s4u_user.cksum.contents != NULL)
+        krb5_free_checksum_contents(context, &rep_s4u_user.cksum);
+    krb5_free_data(context, data);
+
+    return code;
 }
 
 /*
@@ -1919,92 +2104,116 @@ kdc_process_s4u2self_req(krb5_context context,
 			 krb5_kdc_req *request,
 			 krb5_const_principal client_princ,
 			 const krb5_db_entry *server,
-			 krb5_keyblock *subkey,
+			 krb5_keyblock *tgs_subkey,
+			 krb5_keyblock *tgs_session,
 			 krb5_timestamp kdc_time,
-			 krb5_pa_for_user **for_user,
+			 krb5_pa_s4u_x509_user **s4u_x509_user,
 			 krb5_db_entry *princ,
 			 int *nprincs,
 			 const char **status)
 {
     krb5_error_code		code;
-    krb5_pa_data		**pa_data;
-    krb5_data			req_data;
+    krb5_pa_data		*pa_data;
     krb5_boolean		more;
+    int				flags;
 
     *nprincs = 0;
     memset(princ, 0, sizeof(*princ));
 
-    if (request->padata == NULL) {
-	return 0;
-    }
-
-    for (pa_data = request->padata; *pa_data != NULL; pa_data++) {
-	if ((*pa_data)->pa_type == KRB5_PADATA_FOR_USER)
-	    break;
-    }
-    if (*pa_data == NULL) {
-	return 0;
+    pa_data = find_pa_data(request->padata, KRB5_PADATA_S4U_X509_USER);
+    if (pa_data != NULL) {
+	code = kdc_process_s4u_x509_user(context,
+					 request,
+					 pa_data,
+					 tgs_subkey,
+					 tgs_session,
+					 s4u_x509_user,
+					 status);
+	if (code != 0)
+	    return code;
+    } else {
+	pa_data = find_pa_data(request->padata, KRB5_PADATA_FOR_USER);
+	if (pa_data != NULL) {
+	    code = kdc_process_for_user(context,
+					pa_data,
+					tgs_session,
+					s4u_x509_user,
+					status);
+	    if (code != 0)
+		return code;
+	} else
+	    return 0;
     }
 
-#if 0
     /*
-     * Ignore request if the server principal is a TGS, not so much
-     * to avoid unconstrained tickets being issued (as that would
-     * require knowing the TGS key anyway) but so that we do not
-     * block the server referral path.
+     * We need to compare the client name in the TGT with the requested
+     * server name. Supporting server name aliases without assuming a
+     * global name service makes this difficult to do.
+     *
+     * The comparison below handles the following cases (note that the
+     * term "principal name" below excludes the realm).
+     *
+     * (1) The requested service is a host-based service with two name
+     *     components, in which case we assume the principal name to
+     *     contain sufficient qualifying information. The realm is
+     *     ignored for the purpose of comparison.
+     *
+     * (2) The requested service name is an enterprise principal name:
+     *     the service principal name is compared with the unparsed
+     *     form of the client name (including its realm).
+     *
+     * (3) The requested service is some other name type: an exact
+     *     match is required.
+     *
+     * An alternative would be to look up the server once again with
+     * FLAG_CANONICALIZE | FLAG_CLIENT_REFERRALS_ONLY set, do an exact
+     * match between the returned name and client_princ. However, this
+     * assumes that the client set FLAG_CANONICALIZE when requesting
+     * the TGT and that we have a global name service.
      */
-    if (krb5_is_tgs_principal(server->princ)) {
-	return 0;
-    }
-#endif
-
-    *status = "PROCESS_S4U2SELF_REQUEST";
-
-    req_data.length = (*pa_data)->length;
-    req_data.data = (char *)(*pa_data)->contents;
-
-    code = decode_krb5_pa_for_user(&req_data, for_user);
-    if (code) {
-	return code;
-    }
-
-    if (krb5_princ_type(context, (*for_user)->user) !=
-	KRB5_NT_ENTERPRISE_PRINCIPAL) {
-	*status = "INVALID_S4U2SELF_REQUEST";
-	return KRB5KDC_ERR_POLICY;
+    flags = 0;
+    switch (krb5_princ_type(kdc_context, request->server)) {
+    case KRB5_NT_SRV_HST:		    /* (1) */
+	if (krb5_princ_size(kdc_context, request->server) == 2)
+	    flags |= KRB5_PRINCIPAL_COMPARE_IGNORE_REALM;
+	break;
+    case KRB5_NT_ENTERPRISE_PRINCIPAL:	    /* (2) */
+	flags |= KRB5_PRINCIPAL_COMPARE_ENTERPRISE;
+	break;
+    default:				    /* (3) */
+	break;
     }
 
-    code = verify_s4u2self_checksum(context, subkey, *for_user);
-    if (code) {
-	*status = "INVALID_S4U2SELF_CHECKSUM";
-	krb5_free_pa_for_user(kdc_context, *for_user);
-	*for_user = NULL;
-	return code;
-    }
-    if (!krb5_principal_compare_flags(context, request->server, client_princ,
-				      KRB5_PRINCIPAL_COMPARE_ENTERPRISE)) {
+    if (!krb5_principal_compare_flags(context,
+				      request->server,
+				      client_princ,
+				      flags)) {
 	*status = "INVALID_S4U2SELF_REQUEST";
-	return KRB5KDC_ERR_POLICY;
+	return KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN; /* match Windows error code */
     }
 
     /*
      * Protocol transition is mutually exclusive with renew/forward/etc
-     * as well as user-to-user and constrained delegation.
+     * as well as user-to-user and constrained delegation. This check
+     * is also made in validate_as_request().
      *
      * We can assert from this check that the header ticket was a TGT, as
      * that is validated previously in validate_tgs_request().
      */
-    if (request->kdc_options & (NO_TGT_OPTION | KDC_OPT_ENC_TKT_IN_SKEY | KDC_OPT_CNAME_IN_ADDL_TKT)) {
+    if (request->kdc_options & AS_INVALID_OPTIONS) {
+	*status = "INVALID AS OPTIONS";
 	return KRB5KDC_ERR_BADOPTION;
     }
 
     /*
      * Do not attempt to lookup principals in foreign realms.
      */
-    if (is_local_principal((*for_user)->user)) {
+    if (is_local_principal((*s4u_x509_user)->user_id.user)) {
+	krb5_db_entry no_server;
+
 	*nprincs = 1;
 	code = krb5_db_get_principal_ext(kdc_context,
-					 (*for_user)->user,
+					 (*s4u_x509_user)->user_id.user,
 					 KRB5_KDB_FLAG_INCLUDE_PAC,
 					 princ, nprincs, &more);
 	if (code) {
@@ -2021,14 +2230,15 @@ kdc_process_s4u2self_req(krb5_context context,
 	    return KRB5KDC_ERR_C_PRINCIPAL_UNKNOWN;
 	}
 
-	code = validate_s4u2self_request(request, princ, kdc_time, status);
+	memset(&no_server, 0, sizeof(no_server));
+
+	code = validate_as_request(request, *princ,
+				   no_server, kdc_time, status);
 	if (code) {
 	    return code;
 	}
     }
 
-    *status = NULL;
-
     return 0;
 }
 
@@ -2049,7 +2259,7 @@ check_allowed_to_delegate_to(krb5_context context,
 
     /* Must be in same realm */
     if (!krb5_realm_compare(context, server->princ, proxy)) {
-	return KRB5KDC_ERR_BADOPTION;
+	return KRB5KDC_ERR_POLICY;
     }
 
     req.server = server;
@@ -2345,3 +2555,63 @@ log_tgs_alt_tgt(krb5_principal p)
     /* OpenSolaris: audit_krb5kdc_tgs_req_alt_tgt(...) */
 }
 
+krb5_boolean
+enctype_requires_etype_info_2(krb5_enctype enctype)
+{
+    switch(enctype) {
+    case ENCTYPE_DES_CBC_CRC:
+    case ENCTYPE_DES_CBC_MD4:
+    case ENCTYPE_DES_CBC_MD5:
+    case ENCTYPE_DES3_CBC_SHA1:
+    case ENCTYPE_DES3_CBC_RAW:
+    case ENCTYPE_ARCFOUR_HMAC:
+    case ENCTYPE_ARCFOUR_HMAC_EXP :
+	return 0;
+    default:
+	return krb5_c_valid_enctype(enctype);
+    }
+}
+
+/* XXX where are the generic helper routines for this? */
+krb5_error_code
+add_pa_data_element(krb5_context context,
+		    krb5_pa_data *padata,
+		    krb5_pa_data ***inout_padata,
+		    krb5_boolean copy)
+{
+    int				i;
+    krb5_pa_data		**p;
+
+    if (*inout_padata != NULL) {
+	for (i = 0; (*inout_padata)[i] != NULL; i++)
+	    ;
+    } else
+	i = 0;
+
+    p = realloc(*inout_padata, (i + 2) * sizeof(krb5_pa_data *));
+    if (p == NULL)
+	return ENOMEM;
+
+    *inout_padata = p;
+
+    p[i] = (krb5_pa_data *)malloc(sizeof(krb5_pa_data));
+    if (p[i] == NULL)
+	return ENOMEM;
+    *(p[i]) = *padata;
+
+    p[i + 1] = NULL;
+
+    if (copy) {
+	p[i]->contents = (krb5_octet *)malloc(padata->length);
+	if (p[i]->contents == NULL) {
+	    free(p[i]);
+	    p[i] = NULL;
+	    return ENOMEM;
+	}
+
+	memcpy(p[i]->contents, padata->contents, padata->length);
+    }
+
+    return 0;
+}
+
diff --git a/src/kdc/kdc_util.h b/src/kdc/kdc_util.h
index 060442604..cb8fb5f7a 100644
--- a/src/kdc/kdc_util.h
+++ b/src/kdc/kdc_util.h
@@ -150,6 +150,8 @@ int against_local_policy_tgs (krb5_kdc_req *, krb5_db_entry,
 					krb5_ticket *, const char **);
 
 /* kdc_preauth.c */
+krb5_boolean enctype_requires_etype_info_2(krb5_enctype enctype);
+
 const char * missing_required_preauth
     (krb5_db_entry *client, krb5_db_entry *server,
 	       krb5_enc_tkt_part *enc_tkt_reply);
@@ -177,6 +179,12 @@ krb5_error_code free_padata_context
 krb5_pa_data *find_pa_data
     (krb5_pa_data **padata, krb5_preauthtype pa_type);
 
+krb5_error_code add_pa_data_element
+    (krb5_context context,
+		    krb5_pa_data *padata,
+		    krb5_pa_data ***out_padata,
+		    krb5_boolean copy);
+
 /* kdc_authdata.c */
 krb5_error_code load_authdata_plugins(krb5_context context);
 krb5_error_code unload_authdata_plugins(krb5_context context);
@@ -239,13 +247,22 @@ krb5_error_code kdc_process_s4u2self_req
 		krb5_kdc_req *request,
 		krb5_const_principal client_princ,
 		const krb5_db_entry *server,
-		krb5_keyblock *subkey,
+		krb5_keyblock *tgs_subkey,
+		krb5_keyblock *tgs_session,
 		krb5_timestamp kdc_time,
-		krb5_pa_for_user **s4u2_req,
+		krb5_pa_s4u_x509_user **s4u2self_req,
 		krb5_db_entry *princ,
 		int *nprincs,
 		const char **status);
 
+krb5_error_code kdc_make_s4u2self_rep
+	(krb5_context context,
+		krb5_keyblock *tgs_subkey,
+		krb5_keyblock *tgs_session,
+		krb5_pa_s4u_x509_user *req_s4u_user,
+		krb5_kdc_rep *reply,
+		krb5_enc_kdc_rep_part *reply_encpart);
+
 krb5_error_code kdc_process_s4u2proxy_req
 	(krb5_context context,
 		krb5_kdc_req *request,
diff --git a/src/lib/crypto/krb/enc_provider/Makefile.in b/src/lib/crypto/krb/enc_provider/Makefile.in
new file mode 100644
index 000000000..2eedf1d9d
--- /dev/null
+++ b/src/lib/crypto/krb/enc_provider/Makefile.in
@@ -0,0 +1,41 @@
+thisconfigdir=../../../..
+myfulldir=lib/crypto/krb/enc_provider
+mydir=lib/crypto/krb/enc_provider
+BUILDTOP=$(REL)..$(S)..$(S)..$(S)..
+LOCALINCLUDES = -I$(srcdir)/../../@CRYPTO_IMPL@/des -I$(srcdir)/../../@CRYPTO_IMPL@/arcfour 	\
+		-I$(srcdir)/../../@CRYPTO_IMPL@/aes -I$(srcdir)/.. -I$(srcdir)/../../@CRYPTO_IMPL@ 
+DEFS=
+
+##DOS##BUILDTOP = ..\..\..\..
+##DOS##PREFIXDIR=enc_provider
+##DOS##OBJFILE=..\$(OUTPRE)enc_prov.lst
+
+PROG_LIBPATH=-L$(TOPLIBD)
+PROG_RPATH=$(KRB5_LIBDIR)
+
+STLIBOBJS= des.o des3.o rc4.o aes.o 
+
+OBJS= \
+	$(OUTPRE)des.$(OBJEXT) \
+	$(OUTPRE)des3.$(OBJEXT) \
+	$(OUTPRE)aes.$(OBJEXT) \
+	$(OUTPRE)rc4.$(OBJEXT)
+
+SRCS= \
+	$(srcdir)/des.c \
+	$(srcdir)/des3.c \
+	$(srcdir)/aes.c \
+	$(srcdir)/rc4.c
+
+##DOS##LIBOBJS = $(OBJS)
+
+all-unix:: all-libobjs
+
+includes:: depend
+
+depend:: $(SRCS)
+
+clean-unix:: clean-libobjs
+
+@libobj_frag@
+
diff --git a/src/lib/crypto/krb/enc_provider/aes.c b/src/lib/crypto/krb/enc_provider/aes.c
new file mode 100644
index 000000000..060d119c4
--- /dev/null
+++ b/src/lib/crypto/krb/enc_provider/aes.c
@@ -0,0 +1,415 @@
+/*
+ * lib/crypto/enc_provider/aes.c
+ *
+ * Copyright (C) 2003, 2007, 2008 by the Massachusetts Institute of Technology.
+ * All rights reserved.
+ *
+ * Export of this software from the United States of America may
+ *   require a specific license from the United States Government.
+ *   It is the responsibility of any person or organization contemplating
+ *   export to obtain such a license before exporting.
+ *
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of M.I.T. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission.  Furthermore if you modify this software you must label
+ * your software as modified software and not distribute it in such a
+ * fashion that it might be confused with the original M.I.T. software.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is" without express
+ * or implied warranty.
+ */
+
+#include "k5-int.h"
+#include "enc_provider.h"
+#include "aes.h"
+#include "../aead.h"
+
+#if 0
+aes_rval aes_blk_len(unsigned int blen, aes_ctx cx[1]);
+aes_rval aes_enc_key(const unsigned char in_key[], unsigned int klen, aes_ctx cx[1]);
+aes_rval aes_enc_blk(const unsigned char in_blk[], unsigned char out_blk[], const aes_ctx cx[1]);
+aes_rval aes_dec_key(const unsigned char in_key[], unsigned int klen, aes_ctx cx[1]);
+aes_rval aes_dec_blk(const unsigned char in_blk[], unsigned char out_blk[], const aes_ctx cx[1]);
+#endif
+
+#define CHECK_SIZES 0
+
+#if 0
+static void printd (const char *descr, krb5_data *d) {
+    int i, j;
+    const int r = 16;
+
+    printf("%s:", descr);
+
+    for (i = 0; i < d->length; i += r) {
+	printf("\n  %04x: ", i);
+	for (j = i; j < i + r && j < d->length; j++)
+	    printf(" %02x", 0xff & d->data[j]);
+#ifdef SHOW_TEXT
+	for (; j < i + r; j++)
+	    printf("   ");
+	printf("   ");
+	for (j = i; j < i + r && j < d->length; j++) {
+	    int c = 0xff & d->data[j];
+	    printf("%c", isprint(c) ? c : '.');
+	}
+#endif
+    }
+    printf("\n");
+}
+#endif
+
+static inline void enc(char *out, const char *in, aes_ctx *ctx)
+{
+    if (aes_enc_blk((const unsigned char *)in, (unsigned char *)out, ctx)
+	!= aes_good)
+	abort();
+}
+static inline void dec(char *out, const char *in, aes_ctx *ctx)
+{
+    if (aes_dec_blk((const unsigned char *)in, (unsigned char *)out, ctx)
+	!= aes_good)
+	abort();
+}
+
+static void xorblock(char *out, const char *in)
+{
+    int z;
+    for (z = 0; z < BLOCK_SIZE; z++)
+	out[z] ^= in[z];
+}
+
+krb5_error_code
+krb5int_aes_encrypt(const krb5_keyblock *key, const krb5_data *ivec,
+		    const krb5_data *input, krb5_data *output)
+{
+    aes_ctx ctx;
+    char tmp[BLOCK_SIZE], tmp2[BLOCK_SIZE], tmp3[BLOCK_SIZE];
+    int nblocks = 0, blockno;
+
+/*    CHECK_SIZES; */
+
+    if (aes_enc_key(key->contents, key->length, &ctx) != aes_good)
+	abort();
+
+    if (ivec)
+	memcpy(tmp, ivec->data, BLOCK_SIZE);
+    else
+	memset(tmp, 0, BLOCK_SIZE);
+
+    nblocks = (input->length + BLOCK_SIZE - 1) / BLOCK_SIZE;
+
+    if (nblocks == 1) {
+	/* XXX Used for DK function.  */
+	enc(output->data, input->data, &ctx);
+    } else {
+	unsigned int nleft;
+
+	for (blockno = 0; blockno < nblocks - 2; blockno++) {
+	    xorblock(tmp, input->data + blockno * BLOCK_SIZE);
+	    enc(tmp2, tmp, &ctx);
+	    memcpy(output->data + blockno * BLOCK_SIZE, tmp2, BLOCK_SIZE);
+
+	    /* Set up for next block.  */
+	    memcpy(tmp, tmp2, BLOCK_SIZE);
+	}
+	/* Do final CTS step for last two blocks (the second of which
+	   may or may not be incomplete).  */
+	xorblock(tmp, input->data + (nblocks - 2) * BLOCK_SIZE);
+	enc(tmp2, tmp, &ctx);
+	nleft = input->length - (nblocks - 1) * BLOCK_SIZE;
+	memcpy(output->data + (nblocks - 1) * BLOCK_SIZE, tmp2, nleft);
+	memcpy(tmp, tmp2, BLOCK_SIZE);
+
+	memset(tmp3, 0, sizeof(tmp3));
+	memcpy(tmp3, input->data + (nblocks - 1) * BLOCK_SIZE, nleft);
+	xorblock(tmp, tmp3);
+	enc(tmp2, tmp, &ctx);
+	memcpy(output->data + (nblocks - 2) * BLOCK_SIZE, tmp2, BLOCK_SIZE);
+	if (ivec)
+	    memcpy(ivec->data, tmp2, BLOCK_SIZE);
+    }
+
+    return 0;
+}
+
+krb5_error_code
+krb5int_aes_decrypt(const krb5_keyblock *key, const krb5_data *ivec,
+		    const krb5_data *input, krb5_data *output)
+{
+    aes_ctx ctx;
+    char tmp[BLOCK_SIZE], tmp2[BLOCK_SIZE], tmp3[BLOCK_SIZE];
+    int nblocks = 0, blockno;
+
+    CHECK_SIZES;
+
+    if (aes_dec_key(key->contents, key->length, &ctx) != aes_good)
+	abort();
+
+    if (ivec)
+	memcpy(tmp, ivec->data, BLOCK_SIZE);
+    else
+	memset(tmp, 0, BLOCK_SIZE);
+
+    nblocks = (input->length + BLOCK_SIZE - 1) / BLOCK_SIZE;
+
+    if (nblocks == 1) {
+	if (input->length < BLOCK_SIZE)
+	    abort();
+	dec(output->data, input->data, &ctx);
+    } else {
+
+	for (blockno = 0; blockno < nblocks - 2; blockno++) {
+	    dec(tmp2, input->data + blockno * BLOCK_SIZE, &ctx);
+	    xorblock(tmp2, tmp);
+	    memcpy(output->data + blockno * BLOCK_SIZE, tmp2, BLOCK_SIZE);
+	    memcpy(tmp, input->data + blockno * BLOCK_SIZE, BLOCK_SIZE);
+	}
+	/* Do last two blocks, the second of which (next-to-last block
+	   of plaintext) may be incomplete.  */
+	dec(tmp2, input->data + (nblocks - 2) * BLOCK_SIZE, &ctx);
+	/* Set tmp3 to last ciphertext block, padded.  */
+	memset(tmp3, 0, sizeof(tmp3));
+	memcpy(tmp3, input->data + (nblocks - 1) * BLOCK_SIZE,
+	       input->length - (nblocks - 1) * BLOCK_SIZE);
+	/* Set tmp2 to last (possibly partial) plaintext block, and
+	   save it.  */
+	xorblock(tmp2, tmp3);
+	memcpy(output->data + (nblocks - 1) * BLOCK_SIZE, tmp2,
+	       input->length - (nblocks - 1) * BLOCK_SIZE);
+	/* Maybe keep the trailing part, and copy in the last
+	   ciphertext block.  */
+	memcpy(tmp2, tmp3, input->length - (nblocks - 1) * BLOCK_SIZE);
+	/* Decrypt, to get next to last plaintext block xor previous
+	   ciphertext.  */
+	dec(tmp3, tmp2, &ctx);
+	xorblock(tmp3, tmp);
+	memcpy(output->data + (nblocks - 2) * BLOCK_SIZE, tmp3, BLOCK_SIZE);
+	if (ivec)
+	    memcpy(ivec->data, input->data + (nblocks - 2) * BLOCK_SIZE,
+		   BLOCK_SIZE);
+    }
+
+    return 0;
+}
+
+static krb5_error_code
+krb5int_aes_encrypt_iov(const krb5_keyblock *key,
+		        const krb5_data *ivec,
+		        krb5_crypto_iov *data,
+		        size_t num_data)
+{
+    aes_ctx ctx;
+    char tmp[BLOCK_SIZE], tmp2[BLOCK_SIZE];
+    int nblocks = 0, blockno;
+    size_t input_length, i;
+
+    if (aes_enc_key(key->contents, key->length, &ctx) != aes_good)
+	abort();
+
+    if (ivec != NULL)
+	memcpy(tmp, ivec->data, BLOCK_SIZE);
+    else
+	memset(tmp, 0, BLOCK_SIZE);
+
+    for (i = 0, input_length = 0; i < num_data; i++) {
+	krb5_crypto_iov *iov = &data[i];
+
+	if (ENCRYPT_IOV(iov))
+	    input_length += iov->data.length;
+    }
+
+    nblocks = (input_length + BLOCK_SIZE - 1) / BLOCK_SIZE;
+
+    assert(nblocks > 1);
+
+    {
+	char blockN2[BLOCK_SIZE];   /* second last */
+	char blockN1[BLOCK_SIZE];   /* last block */
+	struct iov_block_state input_pos, output_pos;
+
+	IOV_BLOCK_STATE_INIT(&input_pos);
+	IOV_BLOCK_STATE_INIT(&output_pos);
+
+	for (blockno = 0; blockno < nblocks - 2; blockno++) {
+	    char blockN[BLOCK_SIZE];
+
+	    krb5int_c_iov_get_block((unsigned char *)blockN, BLOCK_SIZE, data, num_data, &input_pos);
+	    xorblock(tmp, blockN);
+	    enc(tmp2, tmp, &ctx);
+	    krb5int_c_iov_put_block(data, num_data, (unsigned char *)tmp2, BLOCK_SIZE, &output_pos);
+
+	    /* Set up for next block.  */
+	    memcpy(tmp, tmp2, BLOCK_SIZE);
+	}
+
+	/* Do final CTS step for last two blocks (the second of which
+	   may or may not be incomplete).  */
+
+	/* First, get the last two blocks */
+	memset(blockN1, 0, sizeof(blockN1)); /* pad last block with zeros */
+	krb5int_c_iov_get_block((unsigned char *)blockN2, BLOCK_SIZE, data, num_data, &input_pos);
+	krb5int_c_iov_get_block((unsigned char *)blockN1, BLOCK_SIZE, data, num_data, &input_pos);
+
+	/* Encrypt second last block */
+	xorblock(tmp, blockN2);
+	enc(tmp2, tmp, &ctx);
+	memcpy(blockN2, tmp2, BLOCK_SIZE); /* blockN2 now contains first block */
+	memcpy(tmp, tmp2, BLOCK_SIZE);
+
+	/* Encrypt last block */
+	xorblock(tmp, blockN1);
+	enc(tmp2, tmp, &ctx);
+	memcpy(blockN1, tmp2, BLOCK_SIZE);
+
+	/* Put the last two blocks back into the iovec (reverse order) */
+	krb5int_c_iov_put_block(data, num_data, (unsigned char *)blockN1, BLOCK_SIZE, &output_pos);
+	krb5int_c_iov_put_block(data, num_data, (unsigned char *)blockN2, BLOCK_SIZE, &output_pos);
+
+	if (ivec != NULL)
+	    memcpy(ivec->data, blockN1, BLOCK_SIZE);
+    }
+
+    return 0;
+}
+
+static krb5_error_code
+krb5int_aes_decrypt_iov(const krb5_keyblock *key,
+		        const krb5_data *ivec,
+		        krb5_crypto_iov *data,
+		        size_t num_data)
+{
+    aes_ctx ctx;
+    char tmp[BLOCK_SIZE], tmp2[BLOCK_SIZE], tmp3[BLOCK_SIZE];
+    int nblocks = 0, blockno;
+    unsigned int i;
+    size_t input_length;
+
+    CHECK_SIZES;
+
+    if (aes_dec_key(key->contents, key->length, &ctx) != aes_good)
+	abort();
+
+    if (ivec != NULL)
+	memcpy(tmp, ivec->data, BLOCK_SIZE);
+    else
+	memset(tmp, 0, BLOCK_SIZE);
+
+    for (i = 0, input_length = 0; i < num_data; i++) {
+	krb5_crypto_iov *iov = &data[i];
+
+	if (ENCRYPT_IOV(iov))
+	    input_length += iov->data.length;
+    }
+
+    nblocks = (input_length + BLOCK_SIZE - 1) / BLOCK_SIZE;
+
+    assert(nblocks > 1);
+
+    {
+	char blockN2[BLOCK_SIZE];   /* second last */
+	char blockN1[BLOCK_SIZE];   /* last block */
+	struct iov_block_state input_pos, output_pos;
+
+	IOV_BLOCK_STATE_INIT(&input_pos);
+	IOV_BLOCK_STATE_INIT(&output_pos);
+
+	for (blockno = 0; blockno < nblocks - 2; blockno++) {
+	    char blockN[BLOCK_SIZE];
+
+	    krb5int_c_iov_get_block((unsigned char *)blockN, BLOCK_SIZE, data, num_data, &input_pos);
+	    dec(tmp2, blockN, &ctx);
+	    xorblock(tmp2, tmp);
+	    krb5int_c_iov_put_block(data, num_data, (unsigned char *)tmp2, BLOCK_SIZE, &output_pos);
+	    memcpy(tmp, blockN, BLOCK_SIZE);
+	}
+
+	/* Do last two blocks, the second of which (next-to-last block
+	   of plaintext) may be incomplete.  */
+
+	/* First, get the last two encrypted blocks */
+	memset(blockN1, 0, sizeof(blockN1)); /* pad last block with zeros */
+	krb5int_c_iov_get_block((unsigned char *)blockN2, BLOCK_SIZE, data, num_data, &input_pos);
+	krb5int_c_iov_get_block((unsigned char *)blockN1, BLOCK_SIZE, data, num_data, &input_pos);
+
+	/* Decrypt second last block */
+	dec(tmp2, blockN2, &ctx);
+	/* Set tmp2 to last (possibly partial) plaintext block, and
+	   save it.  */
+	xorblock(tmp2, blockN1);
+	memcpy(blockN2, tmp2, BLOCK_SIZE);
+
+	/* Maybe keep the trailing part, and copy in the last
+	   ciphertext block.  */
+	input_length %= BLOCK_SIZE;
+	memcpy(tmp2, blockN1, input_length ? input_length : BLOCK_SIZE);
+	dec(tmp3, tmp2, &ctx);
+	xorblock(tmp3, tmp);
+	/* Copy out ivec first before we clobber blockN1 with plaintext */
+	if (ivec != NULL)
+	    memcpy(ivec->data, blockN1, BLOCK_SIZE);
+	memcpy(blockN1, tmp3, BLOCK_SIZE);
+
+	/* Put the last two blocks back into the iovec */
+	krb5int_c_iov_put_block(data, num_data, (unsigned char *)blockN1, BLOCK_SIZE, &output_pos);
+	krb5int_c_iov_put_block(data, num_data, (unsigned char *)blockN2, BLOCK_SIZE, &output_pos);
+    }
+
+    return 0;
+}
+
+static krb5_error_code
+k5_aes_make_key(const krb5_data *randombits, krb5_keyblock *key)
+{
+    if (key->length != 16 && key->length != 32)
+	return(KRB5_BAD_KEYSIZE);
+    if (randombits->length != key->length)
+	return(KRB5_CRYPTO_INTERNAL);
+
+    key->magic = KV5M_KEYBLOCK;
+
+    memcpy(key->contents, randombits->data, randombits->length);
+    return(0);
+}
+
+static krb5_error_code
+krb5int_aes_init_state (const krb5_keyblock *key, krb5_keyusage usage,
+			krb5_data *state)
+{
+    state->length = 16;
+    state->data = (void *) malloc(16);
+    if (state->data == NULL)
+	return ENOMEM;
+    memset(state->data, 0, state->length);
+    return 0;
+}
+
+const struct krb5_enc_provider krb5int_enc_aes128 = {
+    16,
+    16, 16,
+    krb5int_aes_encrypt,
+    krb5int_aes_decrypt,
+    k5_aes_make_key,
+    krb5int_aes_init_state,
+    krb5int_default_free_state,
+    krb5int_aes_encrypt_iov,
+    krb5int_aes_decrypt_iov
+};
+
+const struct krb5_enc_provider krb5int_enc_aes256 = {
+    16,
+    32, 32,
+    krb5int_aes_encrypt,
+    krb5int_aes_decrypt,
+    k5_aes_make_key,
+    krb5int_aes_init_state,
+    krb5int_default_free_state,
+    krb5int_aes_encrypt_iov,
+    krb5int_aes_decrypt_iov
+};
+
diff --git a/src/lib/crypto/krb/enc_provider/deps b/src/lib/crypto/krb/enc_provider/deps
new file mode 100644
index 000000000..064976279
--- /dev/null
+++ b/src/lib/crypto/krb/enc_provider/deps
@@ -0,0 +1,49 @@
+# 
+# Generated makefile dependencies follow.
+#
+des.so des.po $(OUTPRE)des.$(OBJEXT): $(BUILDTOP)/include/autoconf.h \
+  $(BUILDTOP)/include/krb5/krb5.h $(BUILDTOP)/include/osconf.h \
+  $(BUILDTOP)/include/profile.h $(COM_ERR_DEPS) $(SRCTOP)/include/k5-buf.h \
+  $(SRCTOP)/include/k5-err.h $(SRCTOP)/include/k5-gmt_mktime.h \
+  $(SRCTOP)/include/k5-int-pkinit.h $(SRCTOP)/include/k5-int.h \
+  $(SRCTOP)/include/k5-platform.h $(SRCTOP)/include/k5-plugin.h \
+  $(SRCTOP)/include/k5-thread.h $(SRCTOP)/include/krb5.h \
+  $(SRCTOP)/include/krb5/locate_plugin.h $(SRCTOP)/include/krb5/preauth_plugin.h \
+  $(SRCTOP)/include/port-sockets.h $(SRCTOP)/include/socket-utils.h \
+  $(srcdir)/../../builtin/des/des_int.h $(srcdir)/../aead.h \
+  $(srcdir)/../cksumtypes.h des.c enc_provider.h
+des3.so des3.po $(OUTPRE)des3.$(OBJEXT): $(BUILDTOP)/include/autoconf.h \
+  $(BUILDTOP)/include/krb5/krb5.h $(BUILDTOP)/include/osconf.h \
+  $(BUILDTOP)/include/profile.h $(COM_ERR_DEPS) $(SRCTOP)/include/k5-buf.h \
+  $(SRCTOP)/include/k5-err.h $(SRCTOP)/include/k5-gmt_mktime.h \
+  $(SRCTOP)/include/k5-int-pkinit.h $(SRCTOP)/include/k5-int.h \
+  $(SRCTOP)/include/k5-platform.h $(SRCTOP)/include/k5-plugin.h \
+  $(SRCTOP)/include/k5-thread.h $(SRCTOP)/include/krb5.h \
+  $(SRCTOP)/include/krb5/locate_plugin.h $(SRCTOP)/include/krb5/preauth_plugin.h \
+  $(SRCTOP)/include/port-sockets.h $(SRCTOP)/include/socket-utils.h \
+  $(srcdir)/../../builtin/des/des_int.h $(srcdir)/../aead.h \
+  $(srcdir)/../cksumtypes.h des3.c
+aes.so aes.po $(OUTPRE)aes.$(OBJEXT): $(BUILDTOP)/include/autoconf.h \
+  $(BUILDTOP)/include/krb5/krb5.h $(BUILDTOP)/include/osconf.h \
+  $(BUILDTOP)/include/profile.h $(COM_ERR_DEPS) $(SRCTOP)/include/k5-buf.h \
+  $(SRCTOP)/include/k5-err.h $(SRCTOP)/include/k5-gmt_mktime.h \
+  $(SRCTOP)/include/k5-int-pkinit.h $(SRCTOP)/include/k5-int.h \
+  $(SRCTOP)/include/k5-platform.h $(SRCTOP)/include/k5-plugin.h \
+  $(SRCTOP)/include/k5-thread.h $(SRCTOP)/include/krb5.h \
+  $(SRCTOP)/include/krb5/locate_plugin.h $(SRCTOP)/include/krb5/preauth_plugin.h \
+  $(SRCTOP)/include/port-sockets.h $(SRCTOP)/include/socket-utils.h \
+  $(srcdir)/../../builtin/aes/aes.h $(srcdir)/../../builtin/aes/uitypes.h \
+  $(srcdir)/../aead.h $(srcdir)/../cksumtypes.h aes.c \
+  enc_provider.h
+rc4.so rc4.po $(OUTPRE)rc4.$(OBJEXT): $(BUILDTOP)/include/autoconf.h \
+  $(BUILDTOP)/include/krb5/krb5.h $(BUILDTOP)/include/osconf.h \
+  $(BUILDTOP)/include/profile.h $(COM_ERR_DEPS) $(SRCTOP)/include/k5-buf.h \
+  $(SRCTOP)/include/k5-err.h $(SRCTOP)/include/k5-gmt_mktime.h \
+  $(SRCTOP)/include/k5-int-pkinit.h $(SRCTOP)/include/k5-int.h \
+  $(SRCTOP)/include/k5-platform.h $(SRCTOP)/include/k5-plugin.h \
+  $(SRCTOP)/include/k5-thread.h $(SRCTOP)/include/krb5.h \
+  $(SRCTOP)/include/krb5/locate_plugin.h $(SRCTOP)/include/krb5/preauth_plugin.h \
+  $(SRCTOP)/include/port-sockets.h $(SRCTOP)/include/socket-utils.h \
+  $(srcdir)/../../builtin/arcfour/arcfour-int.h $(srcdir)/../../builtin/arcfour/arcfour.h \
+  $(srcdir)/../aead.h $(srcdir)/../cksumtypes.h enc_provider.h \
+  rc4.c
diff --git a/src/lib/crypto/krb/enc_provider/des.c b/src/lib/crypto/krb/enc_provider/des.c
new file mode 100644
index 000000000..547f6b976
--- /dev/null
+++ b/src/lib/crypto/krb/enc_provider/des.c
@@ -0,0 +1,181 @@
+/*
+ * Copyright (C) 1998 by the FundsXpress, INC.
+ * 
+ * All rights reserved.
+ * 
+ * Export of this software from the United States of America may require
+ * a specific license from the United States Government.  It is the
+ * responsibility of any person or organization contemplating export to
+ * obtain such a license before exporting.
+ * 
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of FundsXpress. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission.  FundsXpress makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is" without express
+ * or implied warranty.
+ * 
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#include "k5-int.h"
+#include "des_int.h"
+#include "enc_provider.h"
+#include "aead.h"
+
+static krb5_error_code
+k5_des_docrypt(const krb5_keyblock *key, const krb5_data *ivec,
+	       const krb5_data *input, krb5_data *output, int enc)
+{
+    mit_des_key_schedule schedule;
+
+    /* key->enctype was checked by the caller */
+
+    if (key->length != 8)
+	return(KRB5_BAD_KEYSIZE);
+    if ((input->length%8) != 0)
+	return(KRB5_BAD_MSIZE);
+    if (ivec && (ivec->length != 8))
+	return(KRB5_BAD_MSIZE);
+    if (input->length != output->length)
+	return(KRB5_BAD_MSIZE);
+
+    switch (mit_des_key_sched(key->contents, schedule)) {
+    case -1:
+	return(KRB5DES_BAD_KEYPAR);
+    case -2:
+	return(KRB5DES_WEAK_KEY);
+    }
+
+    /* this has a return value, but the code always returns zero */
+
+    mit_des_cbc_encrypt((krb5_pointer) input->data,
+			(krb5_pointer) output->data, input->length,
+			schedule,
+			(ivec
+			 ? (const unsigned char *) ivec->data
+			 : (const unsigned char *) mit_des_zeroblock),
+			enc);
+
+    memset(schedule, 0, sizeof(schedule));
+
+    return(0);
+}
+
+static krb5_error_code
+k5_des_encrypt(const krb5_keyblock *key, const krb5_data *ivec,
+	       const krb5_data *input, krb5_data *output)
+{
+    return(k5_des_docrypt(key, ivec, input, output, 1));
+}
+
+static krb5_error_code
+k5_des_decrypt(const krb5_keyblock *key, const krb5_data *ivec,
+	       const krb5_data *input, krb5_data *output)
+{
+    return(k5_des_docrypt(key, ivec, input, output, 0));
+}
+
+static krb5_error_code
+k5_des_make_key(const krb5_data *randombits, krb5_keyblock *key)
+{
+    if (key->length != 8)
+	return(KRB5_BAD_KEYSIZE);
+    if (randombits->length != 7)
+	return(KRB5_CRYPTO_INTERNAL);
+
+    key->magic = KV5M_KEYBLOCK;
+    key->length = 8;
+
+    /* take the seven bytes, move them around into the top 7 bits of the
+       8 key bytes, then compute the parity bits */
+
+    memcpy(key->contents, randombits->data, randombits->length);
+    key->contents[7] = (((key->contents[0]&1)<<1) | ((key->contents[1]&1)<<2) |
+			((key->contents[2]&1)<<3) | ((key->contents[3]&1)<<4) |
+			((key->contents[4]&1)<<5) | ((key->contents[5]&1)<<6) |
+			((key->contents[6]&1)<<7));
+
+    mit_des_fixup_key_parity(key->contents);
+
+    return(0);
+}
+
+static krb5_error_code
+k5_des_docrypt_iov(const krb5_keyblock *key, const krb5_data *ivec,
+		   krb5_crypto_iov *data, size_t num_data, int enc)
+{
+    mit_des_key_schedule schedule;
+    size_t input_length = 0;
+    unsigned int i;
+
+    /* key->enctype was checked by the caller */
+
+    if (key->length != 8)
+	return(KRB5_BAD_KEYSIZE);
+
+    for (i = 0; i < num_data; i++) {
+	const krb5_crypto_iov *iov = &data[i];
+
+	if (ENCRYPT_DATA_IOV(iov))
+	    input_length += iov->data.length;
+    }
+
+    if ((input_length % 8) != 0)
+	return(KRB5_BAD_MSIZE);
+    if (ivec && (ivec->length != 8))
+	return(KRB5_BAD_MSIZE);
+
+    switch (mit_des_key_sched(key->contents, schedule)) {
+    case -1:
+	return(KRB5DES_BAD_KEYPAR);
+    case -2:
+	return(KRB5DES_WEAK_KEY);
+    }
+
+    /* this has a return value, but the code always returns zero */
+    if (enc)
+	krb5int_des_cbc_encrypt_iov(data, num_data, schedule, ivec ? ivec->data : NULL);
+    else
+	krb5int_des_cbc_decrypt_iov(data, num_data, schedule, ivec ? ivec->data : NULL);
+
+    memset(schedule, 0, sizeof(schedule));
+
+    return(0);
+}
+
+static krb5_error_code
+k5_des_encrypt_iov(const krb5_keyblock *key,
+		    const krb5_data *ivec,
+		    krb5_crypto_iov *data,
+		    size_t num_data)
+{
+    return k5_des_docrypt_iov(key, ivec, data, num_data, 1);
+}
+
+static krb5_error_code
+k5_des_decrypt_iov(const krb5_keyblock *key,
+		   const krb5_data *ivec,
+		   krb5_crypto_iov *data,
+		   size_t num_data)
+{
+    return k5_des_docrypt_iov(key, ivec, data, num_data, 0);
+}
+
+const struct krb5_enc_provider krb5int_enc_des = {
+    8,
+    7, 8,
+    k5_des_encrypt,
+    k5_des_decrypt,
+    k5_des_make_key,
+    krb5int_des_init_state,
+    krb5int_default_free_state,
+    k5_des_encrypt_iov,
+    k5_des_decrypt_iov
+};
diff --git a/src/lib/crypto/krb/enc_provider/des3.c b/src/lib/crypto/krb/enc_provider/des3.c
new file mode 100644
index 000000000..412c994a7
--- /dev/null
+++ b/src/lib/crypto/krb/enc_provider/des3.c
@@ -0,0 +1,221 @@
+/*
+ * Copyright (C) 1998 by the FundsXpress, INC.
+ * 
+ * All rights reserved.
+ * 
+ * Export of this software from the United States of America may require
+ * a specific license from the United States Government.  It is the
+ * responsibility of any person or organization contemplating export to
+ * obtain such a license before exporting.
+ * 
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of FundsXpress. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission.  FundsXpress makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is" without express
+ * or implied warranty.
+ * 
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#include "k5-int.h"
+#include "des_int.h"
+#include "../aead.h"
+
+static krb5_error_code
+validate_and_schedule(const krb5_keyblock *key, const krb5_data *ivec,
+		      const krb5_data *input, const krb5_data *output,
+		      mit_des3_key_schedule *schedule)
+{
+    /* key->enctype was checked by the caller */
+
+    if (key->length != 24)
+	return(KRB5_BAD_KEYSIZE);
+    if ((input->length%8) != 0)
+	return(KRB5_BAD_MSIZE);
+    if (ivec && (ivec->length != 8))
+	return(KRB5_BAD_MSIZE);
+    if (input->length != output->length)
+	return(KRB5_BAD_MSIZE);
+
+    switch (mit_des3_key_sched(*(mit_des3_cblock *)key->contents,
+			       *schedule)) {
+    case -1:
+	return(KRB5DES_BAD_KEYPAR);
+    case -2:
+	return(KRB5DES_WEAK_KEY);
+    }
+    return 0;
+}
+
+static krb5_error_code
+validate_and_schedule_iov(const krb5_keyblock *key, const krb5_data *ivec,
+			  const krb5_crypto_iov *data, size_t num_data,
+			  mit_des3_key_schedule *schedule)
+{
+    size_t i, input_length;
+
+    for (i = 0, input_length = 0; i < num_data; i++) {
+	const krb5_crypto_iov *iov = &data[i];
+
+	if (ENCRYPT_IOV(iov))
+	    input_length += iov->data.length;
+    }
+
+    if (key->length != 24)
+	return(KRB5_BAD_KEYSIZE);
+    if ((input_length%8) != 0)
+	return(KRB5_BAD_MSIZE);
+    if (ivec && (ivec->length != 8))
+	return(KRB5_BAD_MSIZE);
+
+    switch (mit_des3_key_sched(*(mit_des3_cblock *)key->contents,
+			       *schedule)) {
+    case -1:
+	return(KRB5DES_BAD_KEYPAR);
+    case -2:
+	return(KRB5DES_WEAK_KEY);
+    }
+    return 0;
+}
+
+static krb5_error_code
+k5_des3_encrypt(const krb5_keyblock *key, const krb5_data *ivec,
+		const krb5_data *input, krb5_data *output)
+{
+    mit_des3_key_schedule schedule;
+    krb5_error_code err;
+
+    err = validate_and_schedule(key, ivec, input, output, &schedule);
+    if (err)
+	return err;
+
+    /* this has a return value, but the code always returns zero */
+    krb5int_des3_cbc_encrypt((krb5_pointer) input->data,
+			     (krb5_pointer) output->data, input->length,
+			     schedule[0], schedule[1], schedule[2],
+			     ivec?(const unsigned char *) ivec->data:(const unsigned char *)mit_des_zeroblock);
+
+    zap(schedule, sizeof(schedule));
+
+    return(0);
+}
+
+static krb5_error_code
+k5_des3_decrypt(const krb5_keyblock *key, const krb5_data *ivec,
+		const krb5_data *input, krb5_data *output)
+{
+    mit_des3_key_schedule schedule;
+    krb5_error_code err;
+
+    err = validate_and_schedule(key, ivec, input, output, &schedule);
+    if (err)
+	return err;
+
+    /* this has a return value, but the code always returns zero */
+    krb5int_des3_cbc_decrypt((krb5_pointer) input->data,
+			     (krb5_pointer) output->data, input->length,
+			     schedule[0], schedule[1], schedule[2],
+			     ivec?(const unsigned char *) ivec->data:(const unsigned char *)mit_des_zeroblock);
+
+    zap(schedule, sizeof(schedule));
+
+    return(0);
+}
+
+static krb5_error_code
+k5_des3_make_key(const krb5_data *randombits, krb5_keyblock *key)
+{
+    int i;
+
+    if (key->length != 24)
+	return(KRB5_BAD_KEYSIZE);
+    if (randombits->length != 21)
+	return(KRB5_CRYPTO_INTERNAL);
+
+    key->magic = KV5M_KEYBLOCK;
+    key->length = 24;
+
+    /* take the seven bytes, move them around into the top 7 bits of the
+       8 key bytes, then compute the parity bits.  Do this three times. */
+
+    for (i=0; i<3; i++) {
+	memcpy(key->contents+i*8, randombits->data+i*7, 7);
+	key->contents[i*8+7] = (((key->contents[i*8]&1)<<1) |
+				((key->contents[i*8+1]&1)<<2) |
+				((key->contents[i*8+2]&1)<<3) |
+				((key->contents[i*8+3]&1)<<4) |
+				((key->contents[i*8+4]&1)<<5) |
+				((key->contents[i*8+5]&1)<<6) |
+				((key->contents[i*8+6]&1)<<7));
+
+	mit_des_fixup_key_parity(key->contents+i*8);
+    }
+
+    return(0);
+}
+
+static krb5_error_code
+k5_des3_encrypt_iov(const krb5_keyblock *key,
+		    const krb5_data *ivec,
+		    krb5_crypto_iov *data,
+		    size_t num_data)
+{
+    mit_des3_key_schedule schedule;
+    krb5_error_code err;
+
+    err = validate_and_schedule_iov(key, ivec, data, num_data, &schedule);
+    if (err)
+	return err;
+
+    /* this has a return value, but the code always returns zero */
+    krb5int_des3_cbc_encrypt_iov(data, num_data,
+			     schedule[0], schedule[1], schedule[2],
+			     ivec != NULL ? (unsigned char *) ivec->data : NULL);
+
+    zap(schedule, sizeof(schedule));
+
+    return(0);
+}
+
+static krb5_error_code
+k5_des3_decrypt_iov(const krb5_keyblock *key,
+		    const krb5_data *ivec,
+		    krb5_crypto_iov *data,
+		    size_t num_data)
+{
+    mit_des3_key_schedule schedule;
+    krb5_error_code err;
+
+    err = validate_and_schedule_iov(key, ivec, data, num_data, &schedule);
+    if (err)
+	return err;
+
+    /* this has a return value, but the code always returns zero */
+    krb5int_des3_cbc_decrypt_iov(data, num_data,
+				 schedule[0], schedule[1], schedule[2],
+				 ivec != NULL ? (unsigned char *) ivec->data : NULL);
+
+    zap(schedule, sizeof(schedule));
+
+    return(0);
+}
+
+const struct krb5_enc_provider krb5int_enc_des3 = {
+    8,
+    21, 24,
+    k5_des3_encrypt,
+    k5_des3_decrypt,
+    k5_des3_make_key,
+    krb5int_des_init_state,
+    krb5int_default_free_state,
+    k5_des3_encrypt_iov,
+    k5_des3_decrypt_iov
+};
+
diff --git a/src/lib/crypto/krb/enc_provider/enc_provider.h b/src/lib/crypto/krb/enc_provider/enc_provider.h
new file mode 100644
index 000000000..92022b3c8
--- /dev/null
+++ b/src/lib/crypto/krb/enc_provider/enc_provider.h
@@ -0,0 +1,36 @@
+/*
+ * Copyright (C) 1998 by the FundsXpress, INC.
+ * 
+ * All rights reserved.
+ * 
+ * Export of this software from the United States of America may require
+ * a specific license from the United States Government.  It is the
+ * responsibility of any person or organization contemplating export to
+ * obtain such a license before exporting.
+ * 
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of FundsXpress. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission.  FundsXpress makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is" without express
+ * or implied warranty.
+ * 
+ * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
+ * WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+ */
+
+#include "k5-int.h"
+
+extern const struct krb5_enc_provider krb5int_enc_des;
+extern const struct krb5_enc_provider krb5int_enc_des3;
+extern const struct krb5_enc_provider krb5int_enc_arcfour;
+extern const struct krb5_enc_provider krb5int_enc_aes128;
+extern const struct krb5_enc_provider krb5int_enc_aes256;
+extern const struct krb5_enc_provider krb5int_enc_aes128_ctr;
+extern const struct krb5_enc_provider krb5int_enc_aes256_ctr;
+
diff --git a/src/lib/crypto/krb/enc_provider/rc4.c b/src/lib/crypto/krb/enc_provider/rc4.c
new file mode 100644
index 000000000..b950a605b
--- /dev/null
+++ b/src/lib/crypto/krb/enc_provider/rc4.c
@@ -0,0 +1,271 @@
+/* arcfour.c 
+ *
+ * Copyright (c) 2000 by Computer Science Laboratory,
+ *                       Rensselaer Polytechnic Institute
+ *
+ * #include STD_DISCLAIMER
+ */
+
+#include "k5-int.h"
+#include "arcfour-int.h"
+#include "enc_provider.h"
+#include "../aead.h"
+/* gets the next byte from the PRNG */
+#if ((__GNUC__ >= 2) )
+static __inline__ unsigned int k5_arcfour_byte(ArcfourContext *);
+#else
+static unsigned int k5_arcfour_byte(ArcfourContext *);
+#endif /* gcc inlines*/
+
+/* Initializes the context and sets the key. */
+static krb5_error_code k5_arcfour_init(ArcfourContext *ctx, const unsigned char *key, 
+		  unsigned int keylen);
+
+/* Encrypts/decrypts data. */
+static void k5_arcfour_crypt(ArcfourContext *ctx, unsigned char *dest, 
+		     const unsigned char *src, unsigned int len);
+
+/* Interface layer to kerb5 crypto layer */
+static krb5_error_code
+k5_arcfour_docrypt(const krb5_keyblock *, const krb5_data *,
+		   const krb5_data *, krb5_data *);
+
+/* from a random bitstrem, construct a key */
+static krb5_error_code
+k5_arcfour_make_key(const krb5_data *, krb5_keyblock *);
+
+static const unsigned char arcfour_weakkey1[] = {0x00, 0x00, 0xfd};
+static const unsigned char arcfour_weakkey2[] = {0x03, 0xfd, 0xfc};
+static const struct {
+    size_t length;
+    const unsigned char *data;
+} arcfour_weakkeys[] = {
+    { sizeof (arcfour_weakkey1), arcfour_weakkey1},
+    { sizeof (arcfour_weakkey2), arcfour_weakkey2},
+};
+
+static inline unsigned int k5_arcfour_byte(ArcfourContext * ctx)
+{
+  unsigned int x;
+  unsigned int y;
+  unsigned int sx, sy;
+  unsigned char *state;
+
+  state = ctx->state;
+  x = (ctx->x + 1) & 0xff;
+  sx = state[x];
+  y = (sx + ctx->y) & 0xff;
+  sy = state[y];
+  ctx->x = x;
+  ctx->y = y;
+  state[y] = sx;
+  state[x] = sy;
+  return state[(sx + sy) & 0xff];
+}
+
+static void k5_arcfour_crypt(ArcfourContext *ctx, unsigned char *dest, 
+		     const unsigned char *src, unsigned int len)
+{
+  unsigned int i;
+  for (i = 0; i < len; i++)
+    dest[i] = src[i] ^ k5_arcfour_byte(ctx);
+}
+
+
+static krb5_error_code
+k5_arcfour_init(ArcfourContext *ctx, const unsigned char *key, 
+		  unsigned int key_len)
+{
+  unsigned int t, u;
+  unsigned int keyindex;
+  unsigned int stateindex;
+  unsigned char* state;
+  unsigned int counter;
+
+  if (key_len != 16)
+    return KRB5_BAD_MSIZE;     /*this is probably not the correct error code
+				 to return */
+  for (counter=0;
+       counter < sizeof(arcfour_weakkeys)/sizeof(arcfour_weakkeys[0]);
+       counter++)
+      if (!memcmp(key, arcfour_weakkeys[counter].data,
+		  arcfour_weakkeys[counter].length))
+	  return KRB5DES_WEAK_KEY; /* most certainly not the correct error */
+
+  state = &ctx->state[0];
+  ctx->x = 0;
+  ctx->y = 0;
+  for (counter = 0; counter < 256; counter++)
+    state[counter] = counter;
+  keyindex = 0;
+  stateindex = 0;
+  for (counter = 0; counter < 256; counter++)
+    {
+      t = state[counter];
+      stateindex = (stateindex + key[keyindex] + t) & 0xff;
+      u = state[stateindex];
+      state[stateindex] = t;
+      state[counter] = u;
+      if (++keyindex >= key_len)
+	keyindex = 0;
+    }
+  return 0;
+}
+
+
+/* The workhorse of the arcfour system, this impliments the cipher */
+static krb5_error_code
+k5_arcfour_docrypt(const krb5_keyblock *key, const krb5_data *state,
+	       const krb5_data *input, krb5_data *output)
+{
+  ArcfourContext *arcfour_ctx;
+  ArcFourCipherState *cipher_state;
+  int ret;
+
+  if (key->length != 16)
+    return(KRB5_BAD_KEYSIZE);
+  if (state && (state->length != sizeof (ArcFourCipherState)))
+    return(KRB5_BAD_MSIZE);
+  if (input->length != output->length)
+    return(KRB5_BAD_MSIZE);
+
+  if (state) {
+    cipher_state = (ArcFourCipherState *) state->data;
+    arcfour_ctx=&cipher_state->ctx;
+    if (cipher_state->initialized == 0) {
+      if ((ret=k5_arcfour_init(arcfour_ctx, key->contents, key->length))) {
+	return ret;
+      }
+      cipher_state->initialized = 1;
+    }
+    k5_arcfour_crypt(arcfour_ctx, (unsigned char *) output->data, (const unsigned char *) input->data, input->length);
+  }
+  else {
+    arcfour_ctx=malloc(sizeof (ArcfourContext));
+    if (arcfour_ctx == NULL)
+      return ENOMEM;
+    if ((ret=k5_arcfour_init(arcfour_ctx, key->contents, key->length))) {
+      free(arcfour_ctx);
+      return (ret);
+    }
+    k5_arcfour_crypt(arcfour_ctx, (unsigned char * ) output->data,
+		     (const unsigned char * ) input->data, input->length);
+    memset(arcfour_ctx, 0, sizeof (ArcfourContext));
+    free(arcfour_ctx);
+  }
+  
+  return 0;
+}
+
+/* In-place encryption */
+static krb5_error_code
+k5_arcfour_docrypt_iov(const krb5_keyblock *key,
+		       const krb5_data *state,
+		       krb5_crypto_iov *data,
+		       size_t num_data)
+{
+    ArcfourContext *arcfour_ctx = NULL;
+    ArcFourCipherState *cipher_state = NULL;
+    krb5_error_code ret;
+    size_t i;
+
+    if (key->length != 16)
+	return KRB5_BAD_KEYSIZE;
+    if (state != NULL && (state->length != sizeof(ArcFourCipherState)))
+	return KRB5_BAD_MSIZE;
+
+    if (state != NULL) {
+	cipher_state = (ArcFourCipherState *)state->data;
+	arcfour_ctx = &cipher_state->ctx;
+	if (cipher_state->initialized == 0) {
+	    ret = k5_arcfour_init(arcfour_ctx, key->contents, key->length);
+	    if (ret != 0)
+		return ret;
+
+	    cipher_state->initialized = 1;
+	}
+    } else {
+	arcfour_ctx = (ArcfourContext *)malloc(sizeof(ArcfourContext));
+	if (arcfour_ctx == NULL)
+	    return ENOMEM;
+
+	ret = k5_arcfour_init(arcfour_ctx, key->contents, key->length);
+	if (ret != 0) {
+	    free(arcfour_ctx);
+	    return ret;
+	}
+    }
+
+    for (i = 0; i < num_data; i++) {
+	krb5_crypto_iov *iov = &data[i];
+
+	if (ENCRYPT_IOV(iov))
+	    k5_arcfour_crypt(arcfour_ctx, (unsigned char *)iov->data.data,
+			     (const unsigned char *)iov->data.data, iov->data.length);
+    }
+
+    if (state == NULL) {
+	memset(arcfour_ctx, 0, sizeof(ArcfourContext));
+	free(arcfour_ctx);
+    }
+
+    return 0;
+}
+
+static krb5_error_code
+k5_arcfour_make_key(const krb5_data *randombits, krb5_keyblock *key)
+{
+    if (key->length != 16)
+	return(KRB5_BAD_KEYSIZE);
+    if (randombits->length != 16)
+	return(KRB5_CRYPTO_INTERNAL);
+
+    key->magic = KV5M_KEYBLOCK;
+    key->length = 16;
+
+    memcpy(key->contents, randombits->data, randombits->length);
+
+    return(0);
+}
+
+static krb5_error_code
+k5_arcfour_init_state (const krb5_keyblock *key,
+		       krb5_keyusage keyusage, krb5_data *new_state)
+{
+  /* Note that we can't actually set up the state here  because the key
+   * will change  between now and when encrypt is called
+   * because  it is data dependent.  Yeah, this has strange
+   * properties. --SDH
+   */
+  new_state->length = sizeof (ArcFourCipherState);
+  new_state->data = malloc (new_state->length);
+  if (new_state->data) {
+    memset (new_state->data, 0 , new_state->length);
+    /* That will set initialized to zero*/
+  }else {
+    return (ENOMEM);
+  }
+  return 0;
+}
+
+/* Since the arcfour cipher is identical going forwards and backwards, 
+   we just call "docrypt" directly
+*/
+const struct krb5_enc_provider krb5int_enc_arcfour = {
+    /* This seems to work... although I am not sure what the
+       implications are in other places in the kerberos library */
+    1,
+    /* Keysize is arbitrary in arcfour, but the constraints of the
+       system, and to attempt to work with the MSFT system forces us
+       to 16byte/128bit.  Since there is no parity in the key, the
+       byte and length are the same.  */
+    16, 16,
+    k5_arcfour_docrypt,
+    k5_arcfour_docrypt,
+    k5_arcfour_make_key,
+    k5_arcfour_init_state, /*xxx not implemented yet*/
+    krb5int_default_free_state,
+    k5_arcfour_docrypt_iov,
+    k5_arcfour_docrypt_iov
+};
+
diff --git a/src/lib/gssapi/generic/gssapi_ext.h b/src/lib/gssapi/generic/gssapi_ext.h
index 40f5ab809..ce115639b 100644
--- a/src/lib/gssapi/generic/gssapi_ext.h
+++ b/src/lib/gssapi/generic/gssapi_ext.h
@@ -254,6 +254,37 @@ OM_uint32 KRB5_CALLCONV gss_release_iov_buffer
     gss_iov_buffer_desc *, /* iov */
     int);		/* iov_count */
 
+
+/*
+ * Protocol transition
+ */
+OM_uint32 KRB5_CALLCONV
+gss_acquire_cred_impersonate_name(
+    OM_uint32 *,	    /* minor_status */
+    const gss_cred_id_t,    /* impersonator_cred_handle */
+    const gss_name_t,	    /* desired_name */
+    OM_uint32,		    /* time_req */
+    const gss_OID_set,	    /* desired_mechs */
+    gss_cred_usage_t,	    /* cred_usage */
+    gss_cred_id_t *,	    /* output_cred_handle */
+    gss_OID_set *,	    /* actual_mechs */
+    OM_uint32 *);	    /* time_rec */
+
+OM_uint32 KRB5_CALLCONV
+gss_add_cred_impersonate_name(
+    OM_uint32 *,	    /* minor_status */
+    gss_cred_id_t,	    /* input_cred_handle */
+    const gss_cred_id_t,    /* impersonator_cred_handle */
+    const gss_name_t,	    /* desired_name */
+    const gss_OID,	    /* desired_mech */
+    gss_cred_usage_t,	    /* cred_usage */
+    OM_uint32,		    /* initiator_time_req */
+    OM_uint32,		    /* acceptor_time_req */
+    gss_cred_id_t *,	    /* output_cred_handle */
+    gss_OID_set *,	    /* actual_mechs */
+    OM_uint32 *,	    /* initiator_time_rec */
+    OM_uint32 *);	    /* acceptor_time_rec */
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/lib/gssapi/krb5/Makefile.in b/src/lib/gssapi/krb5/Makefile.in
index 2ee9e1d9c..645b91b11 100644
--- a/src/lib/gssapi/krb5/Makefile.in
+++ b/src/lib/gssapi/krb5/Makefile.in
@@ -73,6 +73,7 @@ SRCS = \
 	$(srcdir)/rel_cred.c \
 	$(srcdir)/rel_oid.c \
 	$(srcdir)/rel_name.c \
+	$(srcdir)/s4u_gss_glue.c \
 	$(srcdir)/seal.c \
 	$(srcdir)/set_allowable_enctypes.c \
 	$(srcdir)/ser_sctx.c \
@@ -123,6 +124,7 @@ OBJS = \
 	$(OUTPRE)rel_cred.$(OBJEXT) \
 	$(OUTPRE)rel_oid.$(OBJEXT) \
 	$(OUTPRE)rel_name.$(OBJEXT) \
+	$(OUTPRE)s4u_gss_glue.$(OBJEXT) \
 	$(OUTPRE)seal.$(OBJEXT) \
 	$(OUTPRE)set_allowable_enctypes.$(OBJEXT) \
 	$(OUTPRE)ser_sctx.$(OBJEXT) \
@@ -176,6 +178,7 @@ STLIBOBJS = \
 	rel_cred.o \
 	rel_oid.o \
 	rel_name.o \
+	s4u_gss_glue.o \
 	seal.o \
 	set_allowable_enctypes.o \
 	ser_sctx.o \
diff --git a/src/lib/gssapi/krb5/accept_sec_context.c b/src/lib/gssapi/krb5/accept_sec_context.c
index dd17c044b..d340db7e7 100644
--- a/src/lib/gssapi/krb5/accept_sec_context.c
+++ b/src/lib/gssapi/krb5/accept_sec_context.c
@@ -114,6 +114,53 @@
 
 #ifndef LEAN_CLIENT
 
+static OM_uint32
+create_constrained_deleg_creds(OM_uint32 *minor_status,
+                               krb5_gss_cred_id_t verifier_cred_handle,
+                               krb5_ticket *ticket,
+                               krb5_gss_cred_id_t *out_cred,
+                               krb5_context context)
+{
+    OM_uint32 major_status;
+    krb5_creds krb_creds;
+    krb5_data *data;
+    krb5_error_code code;
+
+    assert(out_cred != NULL);
+    assert(verifier_cred_handle->usage == GSS_C_BOTH);
+
+    memset(&krb_creds, 0, sizeof(krb_creds));
+    krb_creds.client = ticket->enc_part2->client;
+    krb_creds.server = ticket->server;
+    krb_creds.keyblock = *(ticket->enc_part2->session);
+    krb_creds.ticket_flags = ticket->enc_part2->flags;
+    krb_creds.times = ticket->enc_part2->times;
+    krb_creds.magic = KV5M_CREDS;
+    krb_creds.authdata = NULL;
+
+    code = encode_krb5_ticket(ticket, &data);
+    if (code) {
+        *minor_status = code;
+        return GSS_S_FAILURE;
+    }
+
+    krb_creds.ticket = *data;
+
+    major_status = kg_compose_deleg_cred(minor_status,
+                                         verifier_cred_handle,
+                                         &krb_creds,
+                                         GSS_C_INDEFINITE,
+                                         GSS_C_NO_OID_SET,
+                                         out_cred,
+                                         NULL,
+                                         NULL,
+                                         context);
+
+    krb5_free_data(context, data);
+
+    return major_status;
+}
+
 /* Decode, decrypt and store the forwarded creds in the local ccache. */
 static krb5_error_code
 rd_and_store_for_creds(context, auth_context, inbuf, out_cred)
@@ -866,6 +913,23 @@ kg_accept_krb5(minor_status, context_handle,
     ctx->krb_times = ticket->enc_part2->times; /* struct copy */
     ctx->krb_flags = ticket->enc_part2->flags;
 
+    if (delegated_cred_handle != NULL &&
+        deleg_cred == NULL && /* no unconstrained delegation */
+        cred->usage == GSS_C_BOTH &&
+        (ticket->enc_part2->flags & TKT_FLG_FORWARDABLE)) {
+        /*
+         * Now, we always fabricate a delegated credentials handle
+         * containing the service ticket to ourselves, which can be
+         * used for S4U2Proxy.
+         */
+        major_status = create_constrained_deleg_creds(minor_status, cred,
+                                                      ticket, &deleg_cred,
+                                                      context);
+        if (GSS_ERROR(major_status))
+            goto fail;
+        ctx->gss_flags |= GSS_C_DELEG_FLAG;
+    }
+
     krb5_free_ticket(context, ticket); /* Done with ticket */
 
     {
@@ -1055,8 +1119,8 @@ kg_accept_krb5(minor_status, context_handle,
     if (src_name)
         *src_name = (gss_name_t) name;
 
-    if (delegated_cred_handle && deleg_cred) {
-        if (!kg_save_cred_id((gss_cred_id_t) deleg_cred)) {
+    if (delegated_cred_handle) {
+       if (!kg_save_cred_id((gss_cred_id_t) deleg_cred)) {
             major_status = GSS_S_FAILURE;
             code = G_VALIDATE_FAILED;
             goto fail;
diff --git a/src/lib/gssapi/krb5/acquire_cred.c b/src/lib/gssapi/krb5/acquire_cred.c
index 48471b4f4..4427ed763 100644
--- a/src/lib/gssapi/krb5/acquire_cred.c
+++ b/src/lib/gssapi/krb5/acquire_cred.c
@@ -532,8 +532,8 @@ krb5_gss_acquire_cred(minor_status, desired_name, time_req,
 
     cred->usage = cred_usage;
     cred->princ = NULL;
-    cred->prerfc_mech = req_old;
-    cred->rfc_mech = req_new;
+    cred->prerfc_mech = (req_old != 0);
+    cred->rfc_mech = (req_new != 0);
 
 #ifndef LEAN_CLIENT
     cred->keytab = NULL;
@@ -759,3 +759,4 @@ gss_krb5int_set_cred_rcache(OM_uint32 *minor_status,
    *minor_status = 0;
    return GSS_S_COMPLETE;
 }
+
diff --git a/src/lib/gssapi/krb5/gssapiP_krb5.h b/src/lib/gssapi/krb5/gssapiP_krb5.h
index a1073f344..48da87807 100644
--- a/src/lib/gssapi/krb5/gssapiP_krb5.h
+++ b/src/lib/gssapi/krb5/gssapiP_krb5.h
@@ -162,8 +162,9 @@ typedef struct _krb5_gss_cred_id_rec {
     /* name/type of credential */
     gss_cred_usage_t usage;
     krb5_principal princ;        /* this is not interned as a gss_name_t */
-    int prerfc_mech;
-    int rfc_mech;
+    unsigned int prerfc_mech : 1;
+    unsigned int rfc_mech : 1;
+    unsigned int proxy_cred : 1;
 
     /* keytab (accept) data */
     krb5_keytab keytab;
@@ -466,6 +467,29 @@ krb5_boolean kg_integ_only_iov(gss_iov_buffer_desc *iov, int iov_count);
 
 krb5_error_code kg_allocate_iov(gss_iov_buffer_t iov, size_t size);
 
+krb5_error_code
+krb5_to_gss_cred(krb5_context context,
+                 krb5_creds *creds,
+                 krb5_gss_cred_id_t *out_cred);
+
+OM_uint32
+kg_new_connection(
+    OM_uint32 *minor_status,
+    krb5_gss_cred_id_t cred,
+    gss_ctx_id_t *context_handle,
+    gss_name_t target_name,
+    gss_OID mech_type,
+    OM_uint32 req_flags,
+    OM_uint32 time_req,
+    gss_channel_bindings_t input_chan_bindings,
+    gss_buffer_t input_token,
+    gss_OID *actual_mech_type,
+    gss_buffer_t output_token,
+    OM_uint32 *ret_flags,
+    OM_uint32 *time_rec,
+    krb5_context context,
+    int default_mech);
+
 /** declarations of internal name mechanism functions **/
 
 OM_uint32 krb5_gss_acquire_cred
@@ -766,6 +790,17 @@ OM_uint32 krb5_gss_validate_cred
  gss_cred_id_t               /* cred */
 );
 
+OM_uint32 krb5_gss_acquire_cred_impersonate_name(
+    OM_uint32 *,            /* minor_status */
+    const gss_cred_id_t,    /* impersonator_cred_handle */
+    const gss_name_t,       /* desired_name */
+    OM_uint32,              /* time_req */
+    const gss_OID_set,      /* desired_mechs */
+    gss_cred_usage_t,       /* cred_usage */
+    gss_cred_id_t *,        /* output_cred_handle */
+    gss_OID_set *,          /* actual_mechs */
+    OM_uint32 *);           /* time_rec */
+
 OM_uint32
 krb5_gss_validate_cred_1(OM_uint32 * /* minor_status */,
                          gss_cred_id_t /* cred_handle */,
@@ -790,6 +825,19 @@ OM_uint32 gss_krb5int_unseal_token_v3(krb5_context *contextptr,
 
 int gss_krb5int_rotate_left (void *ptr, size_t bufsiz, size_t rc);
 
+/* s4u_gss_glue.c */
+OM_uint32
+kg_compose_deleg_cred(OM_uint32 *minor_status,
+                      krb5_gss_cred_id_t impersonator_cred,
+                      krb5_creds *subject_creds,
+                      OM_uint32 time_req,
+                      const gss_OID_set desired_mechs,
+                      krb5_gss_cred_id_t *output_cred,
+                      gss_OID_set *actual_mechs,
+                      OM_uint32 *time_rec,
+                      krb5_context context);
+
+
 /*
  * These take unglued krb5-mech-specific contexts.
  */
diff --git a/src/lib/gssapi/krb5/gssapi_krb5.c b/src/lib/gssapi/krb5/gssapi_krb5.c
index a20e59dfb..519abb860 100644
--- a/src/lib/gssapi/krb5/gssapi_krb5.c
+++ b/src/lib/gssapi/krb5/gssapi_krb5.c
@@ -140,6 +140,7 @@ const gss_OID_desc krb5_gss_oid_array[] = {
 
     /* gss_nt_krb5_principal.  Object identifier for a krb5_principal. Do not use. */
     {10, "\052\206\110\206\367\022\001\002\002\002"},
+
     { 0, 0 }
 };
 
@@ -447,13 +448,11 @@ krb5_gss_inquire_cred_by_oid(OM_uint32 *minor_status,
 /*
  * gss_set_sec_context_option() methods
  */
-#if 0
 static struct {
     gss_OID_desc oid;
     OM_uint32 (*func)(OM_uint32 *, gss_ctx_id_t *, const gss_OID, const gss_buffer_t);
 } krb5_gss_set_sec_context_option_ops[] = {
 };
-#endif
 
 static OM_uint32
 krb5_gss_set_sec_context_option (OM_uint32 *minor_status,
@@ -481,12 +480,8 @@ krb5_gss_set_sec_context_option (OM_uint32 *minor_status,
             return GSS_S_NO_CONTEXT;
 
         ctx = (krb5_gss_ctx_id_rec *) context_handle;
-
-        if (!ctx->established)
-            return GSS_S_NO_CONTEXT;
     }
 
-#if 0
     for (i = 0; i < sizeof(krb5_gss_set_sec_context_option_ops)/
                     sizeof(krb5_gss_set_sec_context_option_ops[0]); i++) {
         if (g_OID_prefix_equal(desired_object, &krb5_gss_set_sec_context_option_ops[i].oid)) {
@@ -496,7 +491,6 @@ krb5_gss_set_sec_context_option (OM_uint32 *minor_status,
                                                                   value);
         }
     }
-#endif
 
     *minor_status = EINVAL;
 
@@ -521,7 +515,7 @@ static struct {
     {
         {GSS_KRB5_SET_CRED_RCACHE_OID_LENGTH, GSS_KRB5_SET_CRED_RCACHE_OID},
         gss_krb5int_set_cred_rcache
-    }
+    },
 };
 
 static OM_uint32
@@ -587,7 +581,7 @@ static struct {
     {
         {GSS_KRB5_USE_KDC_CONTEXT_OID_LENGTH, GSS_KRB5_USE_KDC_CONTEXT_OID},
         krb5int_gss_use_kdc_context
-    }
+    },
 };
 
 static OM_uint32
@@ -683,6 +677,8 @@ static struct gss_config krb5_mechanism = {
     krb5_gss_unwrap_iov,
     krb5_gss_wrap_iov_length,
     NULL,               /* complete_auth_token */
+    krb5_gss_acquire_cred_impersonate_name,
+    NULL,               /* krb5_gss_add_cred_impersonate_name */
 };
 
 
diff --git a/src/lib/gssapi/krb5/import_name.c b/src/lib/gssapi/krb5/import_name.c
index 440d36222..6879c766f 100644
--- a/src/lib/gssapi/krb5/import_name.c
+++ b/src/lib/gssapi/krb5/import_name.c
@@ -56,8 +56,7 @@ krb5_gss_import_name(minor_status, input_name_buffer,
     krb5_context context;
     krb5_principal princ;
     krb5_error_code code;
-    unsigned char *cp, *end;
-    char *stringrep, *tmp, *tmp2;
+    char *stringrep, *tmp, *tmp2, *cp;
     OM_uint32    length;
 #ifndef NO_PASSWORD
     struct passwd *pw;
@@ -156,12 +155,7 @@ krb5_gss_import_name(minor_status, input_name_buffer,
             goto do_getpwuid;
 #endif
         } else if (g_OID_equal(input_name_type, gss_nt_exported_name)) {
-#define BOUNDS_CHECK(cp, end, n) do { if ((end) - (cp) < (n)) \
-                    goto fail_name; } while (0)
-            cp = (unsigned char *)tmp;
-            end = cp + input_name_buffer->length;
-
-            BOUNDS_CHECK(cp, end, 4);
+            cp = tmp;
             if (*cp++ != 0x04)
                 goto fail_name;
             if (*cp++ != 0x01)
@@ -169,28 +163,20 @@ krb5_gss_import_name(minor_status, input_name_buffer,
             if (*cp++ != 0x00)
                 goto fail_name;
             length = *cp++;
-            if (length != (ssize_t)gss_mech_krb5->length+2)
+            if (length != gss_mech_krb5->length+2)
                 goto fail_name;
-
-            BOUNDS_CHECK(cp, end, 2);
             if (*cp++ != 0x06)
                 goto fail_name;
             length = *cp++;
             if (length != gss_mech_krb5->length)
                 goto fail_name;
-
-            BOUNDS_CHECK(cp, end, length);
             if (memcmp(cp, gss_mech_krb5->elements, length) != 0)
                 goto fail_name;
             cp += length;
-
-            BOUNDS_CHECK(cp, end, 4);
             length = *cp++;
             length = (length << 8) | *cp++;
             length = (length << 8) | *cp++;
             length = (length << 8) | *cp++;
-
-            BOUNDS_CHECK(cp, end, length);
             tmp2 = malloc(length+1);
             if (tmp2 == NULL) {
                 xfree(tmp);
@@ -198,7 +184,7 @@ krb5_gss_import_name(minor_status, input_name_buffer,
                 krb5_free_context(context);
                 return GSS_S_FAILURE;
             }
-            strncpy(tmp2, (char *)cp, length);
+            strncpy(tmp2, cp, length);
             tmp2[length] = 0;
 
             stringrep = tmp2;
diff --git a/src/lib/gssapi/krb5/init_sec_context.c b/src/lib/gssapi/krb5/init_sec_context.c
index 5559fadbc..0bb4fde02 100644
--- a/src/lib/gssapi/krb5/init_sec_context.c
+++ b/src/lib/gssapi/krb5/init_sec_context.c
@@ -128,25 +128,69 @@ static krb5_error_code get_credentials(context, cred, server, now,
     krb5_creds **out_creds;
 {
     krb5_error_code     code;
-    krb5_creds          in_creds;
+    krb5_creds          in_creds, evidence_creds;
+    krb5_flags          flags = 0;
+    krb5_principal      cc_princ = NULL;
 
     k5_mutex_assert_locked(&cred->lock);
     memset(&in_creds, 0, sizeof(krb5_creds));
+    memset(&evidence_creds, 0, sizeof(krb5_creds));
     in_creds.client = in_creds.server = NULL;
 
-    if ((code = krb5_copy_principal(context, cred->princ, &in_creds.client)))
+    if ((code = krb5_cc_get_principal(context, cred->ccache, &cc_princ)))
         goto cleanup;
-    if ((code = krb5_copy_principal(context, server, &in_creds.server)))
-        goto cleanup;
-    in_creds.times.endtime = endtime;
 
-    in_creds.keyblock.enctype = 0;
+    /*
+     * Do constrained delegation if we have proxy credentials and
+     * we're not trying to get a ticket to ourselves (in which case
+     * we can just use the S4U2Self or evidence ticket directly).
+     */
+    if (cred->proxy_cred &&
+        !krb5_principal_compare(context, cc_princ, server)) {
+        krb5_creds mcreds;
+
+        flags |= KRB5_GC_CANONICALIZE |
+                 KRB5_GC_NO_STORE |
+                 KRB5_GC_CONSTRAINED_DELEGATION;
+
+        memset(&mcreds, 0, sizeof(mcreds));
 
-    code = krb5_get_credentials(context, 0, cred->ccache,
+        mcreds.magic = KV5M_CREDS;
+        mcreds.times.endtime = cred->tgt_expire;
+        mcreds.server = cc_princ;
+        mcreds.client = cred->princ;
+
+        code = krb5_cc_retrieve_cred(context, cred->ccache,
+                                     KRB5_TC_MATCH_TIMES, &mcreds,
+                                     &evidence_creds);
+        if (code)
+            goto cleanup;
+
+        assert(evidence_creds.ticket_flags & TKT_FLG_FORWARDABLE);
+
+        in_creds.client = cc_princ;
+        in_creds.second_ticket = evidence_creds.ticket;
+    } else {
+        in_creds.client = cred->princ;
+    }
+
+    in_creds.server = server;
+    in_creds.times.endtime = endtime;
+
+    code = krb5_get_credentials(context, flags, cred->ccache,
                                 &in_creds, out_creds);
     if (code)
         goto cleanup;
 
+    if (flags & KRB5_GC_CONSTRAINED_DELEGATION) {
+        if (!krb5_principal_compare(context, cred->princ,
+                                    (*out_creds)->client)) {
+            /* server did not support constrained delegation */
+            code = KRB5_KDCREP_MODIFIED;
+            goto cleanup;
+        }
+    }
+
     /*
      * Enforce a stricter limit (without timeskew forgiveness at the
      * boundaries) because accept_sec_context code is also similarly
@@ -159,10 +203,10 @@ static krb5_error_code get_credentials(context, cred, server, now,
     }
 
 cleanup:
-    if (in_creds.client)
-        krb5_free_principal(context, in_creds.client);
-    if (in_creds.server)
-        krb5_free_principal(context, in_creds.server);
+    if (cc_princ)
+        krb5_free_principal(context, cc_princ);
+    krb5_free_cred_contents(context, &evidence_creds);
+
     return code;
 }
 struct gss_checksum_data {
@@ -390,8 +434,8 @@ cleanup:
  *
  * Do the grunt work of setting up a new context.
  */
-static OM_uint32
-new_connection(
+OM_uint32
+kg_new_connection(
     OM_uint32 *minor_status,
     krb5_gss_cred_id_t cred,
     gss_ctx_id_t *context_handle,
@@ -931,12 +975,12 @@ krb5_gss_init_sec_context(minor_status, claimant_cred_handle,
 
     /*SUPPRESS 29*/
     if (*context_handle == GSS_C_NO_CONTEXT) {
-        major_status = new_connection(minor_status, cred, context_handle,
-                                      target_name, mech_type, req_flags,
-                                      time_req, input_chan_bindings,
-                                      input_token, actual_mech_type,
-                                      output_token, ret_flags, time_rec,
-                                      context, default_mech);
+        major_status = kg_new_connection(minor_status, cred, context_handle,
+                                        target_name, mech_type, req_flags,
+                                        time_req, input_chan_bindings,
+                                        input_token, actual_mech_type,
+                                        output_token, ret_flags, time_rec,
+                                        context, default_mech);
         k5_mutex_unlock(&cred->lock);
         if (*context_handle == GSS_C_NO_CONTEXT) {
             save_error_info (*minor_status, context);
diff --git a/src/lib/gssapi/krb5/krb5_gss_glue.c b/src/lib/gssapi/krb5/krb5_gss_glue.c
index f9bf03016..034550122 100644
--- a/src/lib/gssapi/krb5/krb5_gss_glue.c
+++ b/src/lib/gssapi/krb5/krb5_gss_glue.c
@@ -416,3 +416,4 @@ gsskrb5_extract_authtime_from_sec_context(OM_uint32 *minor_status,
 
     return GSS_S_COMPLETE;
 }
+
diff --git a/src/lib/gssapi/krb5/s4u_gss_glue.c b/src/lib/gssapi/krb5/s4u_gss_glue.c
new file mode 100644
index 000000000..8e2d690b1
--- /dev/null
+++ b/src/lib/gssapi/krb5/s4u_gss_glue.c
@@ -0,0 +1,346 @@
+/* -*- mode: c; indent-tabs-mode: nil -*- */
+/*
+ * Copyright 2009  by the Massachusetts Institute of Technology.
+ * All Rights Reserved.
+ *
+ * Export of this software from the United States of America may
+ *   require a specific license from the United States Government.
+ *   It is the responsibility of any person or organization contemplating
+ *   export to obtain such a license before exporting.
+ *
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of M.I.T. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission.  Furthermore if you modify this software you must label
+ * your software as modified software and not distribute it in such a
+ * fashion that it might be confused with the original M.I.T. software.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is" without express
+ * or implied warranty.
+ *
+ */
+#include "k5-int.h"
+#include "gssapiP_krb5.h"
+#ifdef HAVE_MEMORY_H
+#include <memory.h>
+#endif
+#include <assert.h>
+
+static OM_uint32
+kg_set_desired_mechs(OM_uint32 *minor_status,
+                     const gss_OID_set desired_mechs,
+                     krb5_gss_cred_id_t cred)
+{
+    unsigned int i;
+
+    if (desired_mechs == GSS_C_NULL_OID_SET) {
+        cred->prerfc_mech = 1;
+        cred->rfc_mech = 1;
+    } else {
+        cred->prerfc_mech = 0;
+        cred->rfc_mech = 0;
+
+        for (i = 0; i < desired_mechs->count; i++) {
+            if (g_OID_equal(gss_mech_krb5_old, &desired_mechs->elements[i]))
+                cred->prerfc_mech = 1;
+            else if (g_OID_equal(gss_mech_krb5, &desired_mechs->elements[i]))
+                cred->rfc_mech = 1;
+        }
+
+        if (!cred->prerfc_mech && !cred->rfc_mech) {
+            *minor_status = 0;
+            return GSS_S_BAD_MECH;
+        }
+    }
+
+    return GSS_S_COMPLETE;
+}
+
+static OM_uint32
+kg_return_mechs(OM_uint32 *minor_status,
+                krb5_gss_cred_id_t cred,
+                gss_OID_set *actual_mechs)
+{
+    OM_uint32 major_status, minor;
+    gss_OID_set mechs;
+
+    if (actual_mechs == NULL)
+        return GSS_S_COMPLETE;
+
+    major_status = generic_gss_create_empty_oid_set(minor_status, &mechs);
+    if (GSS_ERROR(major_status))
+        return major_status;
+
+    if (cred->prerfc_mech) {
+        major_status = generic_gss_add_oid_set_member(minor_status,
+                                                      gss_mech_krb5_old,
+                                                      &mechs);
+        if (GSS_ERROR(major_status)) {
+            generic_gss_release_oid_set(&minor, &mechs);
+            return major_status;
+        }
+    }
+    if (cred->rfc_mech) {
+        major_status = generic_gss_add_oid_set_member(minor_status,
+                                                      gss_mech_krb5,
+                                                      &mechs);
+        if (GSS_ERROR(major_status)) {
+            generic_gss_release_oid_set(&minor, &mechs);
+            return major_status;
+        }
+    }
+
+    *actual_mechs = mechs;
+
+    return GSS_S_COMPLETE;
+}
+
+static int
+kg_is_initiator_cred(krb5_gss_cred_id_t cred)
+{
+    return (cred->usage == GSS_C_INITIATE || cred->usage == GSS_C_BOTH) &&
+           (cred->ccache != NULL);
+}
+
+static OM_uint32
+kg_impersonate_name(OM_uint32 *minor_status,
+                    const krb5_gss_cred_id_t impersonator_cred,
+                    const krb5_principal user,
+                    OM_uint32 time_req,
+                    const gss_OID_set desired_mechs,
+                    krb5_gss_cred_id_t *output_cred,
+                    gss_OID_set *actual_mechs,
+                    OM_uint32 *time_rec,
+                    krb5_context context)
+{
+    OM_uint32 major_status;
+    krb5_error_code code;
+    krb5_creds in_creds, *out_creds = NULL;
+
+    memset(&in_creds, 0, sizeof(in_creds));
+    memset(&out_creds, 0, sizeof(out_creds));
+
+    in_creds.client = user;
+    in_creds.server = impersonator_cred->princ;
+
+    if (impersonator_cred->req_enctypes != NULL)
+        in_creds.keyblock.enctype = impersonator_cred->req_enctypes[0];
+
+    code = krb5_get_credentials_for_user(context,
+                                         KRB5_GC_CANONICALIZE | KRB5_GC_NO_STORE,
+                                         impersonator_cred->ccache,
+                                         &in_creds,
+                                         NULL, &out_creds);
+    if (code != 0) {
+        *minor_status = code;
+        return GSS_S_FAILURE;
+    }
+
+    major_status = kg_compose_deleg_cred(minor_status,
+                                         impersonator_cred,
+                                         out_creds,
+                                         time_req,
+                                         desired_mechs,
+                                         output_cred,
+                                         actual_mechs,
+                                         time_rec,
+                                         context);
+
+    krb5_free_creds(context, out_creds);
+
+    return major_status;
+}
+
+OM_uint32
+krb5_gss_acquire_cred_impersonate_name(OM_uint32 *minor_status,
+                                       const gss_cred_id_t impersonator_cred_handle,
+                                       const gss_name_t desired_name,
+                                       OM_uint32 time_req,
+                                       const gss_OID_set desired_mechs,
+                                       gss_cred_usage_t cred_usage,
+                                       gss_cred_id_t *output_cred_handle,
+                                       gss_OID_set *actual_mechs,
+                                       OM_uint32 *time_rec)
+{
+    OM_uint32 major_status;
+    krb5_error_code code;
+    krb5_gss_cred_id_t cred;
+    krb5_context context;
+
+    if (impersonator_cred_handle == GSS_C_NO_CREDENTIAL)
+        return GSS_S_CALL_INACCESSIBLE_READ;
+
+    if (desired_name == GSS_C_NO_NAME)
+        return GSS_S_CALL_INACCESSIBLE_READ;
+
+    if (output_cred_handle == NULL)
+        return GSS_S_CALL_INACCESSIBLE_WRITE;
+
+    if (cred_usage != GSS_C_INITIATE) {
+        *minor_status = (OM_uint32)G_BAD_USAGE;
+        return GSS_S_FAILURE;
+    }
+
+    *output_cred_handle = GSS_C_NO_CREDENTIAL;
+    if (actual_mechs != NULL)
+        *actual_mechs = GSS_C_NO_OID_SET;
+    if (time_rec != NULL)
+        *time_rec = 0;
+
+    code = krb5_gss_init_context(&context);
+    if (code != 0) {
+        *minor_status = code;
+        return GSS_S_FAILURE;
+    }
+
+    major_status = krb5_gss_validate_cred_1(minor_status,
+                                            impersonator_cred_handle,
+                                            context);
+    if (GSS_ERROR(major_status)) {
+        krb5_free_context(context);
+        return major_status;
+    }
+
+    major_status = kg_impersonate_name(minor_status,
+                                       (krb5_gss_cred_id_t)impersonator_cred_handle,
+                                       (krb5_principal)desired_name,
+                                       time_req,
+                                       desired_mechs,
+                                       &cred,
+                                       actual_mechs,
+                                       time_rec,
+                                       context);
+
+    *output_cred_handle = (gss_cred_id_t)cred;
+
+    k5_mutex_unlock(&((krb5_gss_cred_id_t)impersonator_cred_handle)->lock);
+    krb5_free_context(context);
+
+    return major_status;
+
+}
+
+OM_uint32
+kg_compose_deleg_cred(OM_uint32 *minor_status,
+                      krb5_gss_cred_id_t impersonator_cred,
+                      krb5_creds *subject_creds,
+                      OM_uint32 time_req,
+                      const gss_OID_set desired_mechs,
+                      krb5_gss_cred_id_t *output_cred,
+                      gss_OID_set *actual_mechs,
+                      OM_uint32 *time_rec,
+                      krb5_context context)
+{
+    OM_uint32 major_status;
+    krb5_error_code code;
+    krb5_gss_cred_id_t cred = NULL;
+
+    k5_mutex_assert_locked(&impersonator_cred->lock);
+
+    if (!kg_is_initiator_cred(impersonator_cred) ||
+        impersonator_cred->princ == NULL ||
+        impersonator_cred->proxy_cred) {
+        code = G_BAD_USAGE;
+        goto cleanup;
+    }
+
+    assert(subject_creds != NULL);
+    assert(subject_creds->client != NULL);
+
+    cred = xmalloc(sizeof(*cred));
+    if (cred == NULL) {
+        code = ENOMEM;
+        goto cleanup;
+    }
+    memset(cred, 0, sizeof(*cred));
+
+    code = k5_mutex_init(&cred->lock);
+    if (code != 0)
+        goto cleanup;
+
+    /*
+     * Only return a "proxy" credential for use with constrained
+     * delegation if the subject credentials are forwardable.
+     * Submitting non-forwardable credentials to the KDC for use
+     * with constrained delegation will only return an error.
+     */
+    cred->usage = GSS_C_INITIATE;
+    cred->proxy_cred = !!(subject_creds->ticket_flags & TKT_FLG_FORWARDABLE);
+
+    major_status = kg_set_desired_mechs(minor_status, desired_mechs, cred);
+    if (GSS_ERROR(major_status))
+        goto cleanup;
+
+    cred->tgt_expire = impersonator_cred->tgt_expire;
+
+    code = krb5_copy_principal(context, subject_creds->client, &cred->princ);
+    if (code != 0)
+        goto cleanup;
+
+    code = krb5_cc_new_unique(context, "MEMORY", NULL, &cred->ccache);
+    if (code != 0)
+        goto cleanup;
+
+    code = krb5_cc_initialize(context, cred->ccache,
+                              cred->proxy_cred ? impersonator_cred->princ :
+                                    (krb5_principal)subject_creds->client);
+    if (code != 0)
+        goto cleanup;
+
+    if (cred->proxy_cred) {
+        /* Impersonator's TGT will be necessary for S4U2Proxy */
+        code = krb5_cc_copy_creds(context, impersonator_cred->ccache,
+                                  cred->ccache);
+        if (code != 0)
+            goto cleanup;
+    }
+
+    code = krb5_cc_store_cred(context, cred->ccache, subject_creds);
+    if (code != 0)
+        goto cleanup;
+
+    if (time_rec != NULL) {
+        krb5_timestamp now;
+
+        code = krb5_timeofday(context, &now);
+        if (code != 0)
+            goto cleanup;
+
+        *time_rec = cred->tgt_expire - now;
+    }
+
+    major_status = kg_return_mechs(minor_status, cred, actual_mechs);
+    if (GSS_ERROR(major_status))
+        goto cleanup;
+
+    if (!kg_save_cred_id((gss_cred_id_t)cred)) {
+        code = G_VALIDATE_FAILED;
+        goto cleanup;
+    }
+
+    major_status = GSS_S_COMPLETE;
+    *minor_status = 0;
+    *output_cred = cred;
+
+cleanup:
+    if (code != 0) {
+        *minor_status = code;
+        major_status = GSS_S_FAILURE;
+    }
+
+    if (GSS_ERROR(major_status) && cred != NULL) {
+        k5_mutex_destroy(&cred->lock);
+        if (cred->ccache != NULL)
+            krb5_cc_destroy(context, cred->ccache);
+        if (cred->princ != NULL)
+            krb5_free_principal(context, cred->princ);
+        xfree(cred);
+    }
+
+    return major_status;
+}
+
diff --git a/src/lib/gssapi/krb5/val_cred.c b/src/lib/gssapi/krb5/val_cred.c
index dd82d5341..43b1f695d 100644
--- a/src/lib/gssapi/krb5/val_cred.c
+++ b/src/lib/gssapi/krb5/val_cred.c
@@ -58,7 +58,8 @@ krb5_gss_validate_cred_1(OM_uint32 *minor_status, gss_cred_id_t cred_handle,
             *minor_status = code;
             return(GSS_S_DEFECTIVE_CREDENTIAL);
         }
-        if (!krb5_principal_compare(context, princ, cred->princ)) {
+        if (!cred->proxy_cred &&
+            !krb5_principal_compare(context, princ, cred->princ)) {
             k5_mutex_unlock(&cred->lock);
             *minor_status = KG_CCACHE_NOMATCH;
             return(GSS_S_DEFECTIVE_CREDENTIAL);
diff --git a/src/lib/gssapi/libgssapi_krb5.exports b/src/lib/gssapi/libgssapi_krb5.exports
index 69f390e45..d641fc65b 100644
--- a/src/lib/gssapi/libgssapi_krb5.exports
+++ b/src/lib/gssapi/libgssapi_krb5.exports
@@ -9,8 +9,10 @@ GSS_C_NT_USER_NAME
 GSS_KRB5_NT_PRINCIPAL_NAME
 gss_accept_sec_context
 gss_acquire_cred
+gss_acquire_cred_impersonate_name
 gss_add_buffer_set_member
 gss_add_cred
+gss_add_cred_impersonate_name
 gss_add_oid_set_member
 gss_canonicalize_name
 gss_compare_name
diff --git a/src/lib/gssapi/mechglue/Makefile.in b/src/lib/gssapi/mechglue/Makefile.in
index 927b3755c..18e89f19d 100644
--- a/src/lib/gssapi/mechglue/Makefile.in
+++ b/src/lib/gssapi/mechglue/Makefile.in
@@ -14,6 +14,7 @@ DEFS=-D_GSS_STATIC_LINK=1
 SRCS = \
 	$(srcdir)/g_accept_sec_context.c \
 	$(srcdir)/g_acquire_cred.c \
+	$(srcdir)/g_acquire_cred_imp_name.c \
 	$(srcdir)/g_buffer_set.c \
 	$(srcdir)/g_canon_name.c \
 	$(srcdir)/g_compare_name.c \
@@ -58,6 +59,7 @@ SRCS = \
 OBJS = \
 	$(OUTPRE)g_accept_sec_context.$(OBJEXT) \
 	$(OUTPRE)g_acquire_cred.$(OBJEXT) \
+	$(OUTPRE)g_acquire_cred_imp_name.$(OBJEXT) \
 	$(OUTPRE)g_buffer_set.$(OBJEXT) \
 	$(OUTPRE)g_canon_name.$(OBJEXT) \
 	$(OUTPRE)g_compare_name.$(OBJEXT) \
@@ -102,6 +104,7 @@ OBJS = \
 STLIBOBJS = \
 	g_accept_sec_context.o \
 	g_acquire_cred.o \
+	g_acquire_cred_imp_name.o \
 	g_buffer_set.o \
 	g_canon_name.o \
 	g_compare_name.o \
diff --git a/src/lib/gssapi/mechglue/g_accept_sec_context.c b/src/lib/gssapi/mechglue/g_accept_sec_context.c
index fa703d34d..dc4391593 100644
--- a/src/lib/gssapi/mechglue/g_accept_sec_context.c
+++ b/src/lib/gssapi/mechglue/g_accept_sec_context.c
@@ -121,6 +121,7 @@ gss_cred_id_t *		d_cred;
     gss_name_t		tmp_src_name = GSS_C_NO_NAME;
     gss_OID_desc	token_mech_type_desc;
     gss_OID		token_mech_type = &token_mech_type_desc;
+    gss_OID		actual_mech = GSS_C_NO_OID;
     gss_mechanism	mech;
 
     status = val_acc_sec_ctx_args(minor_status,
@@ -198,8 +199,8 @@ gss_cred_id_t *		d_cred;
 						  input_cred_handle,
 						  input_token_buffer,
 						  input_chan_bindings,
-						  &internal_name,
-						  mech_type,
+						  src_name ? &internal_name : NULL,
+						  &actual_mech,
 						  output_token,
 						  &temp_ret_flags,
 						  time_rec,
@@ -222,110 +223,120 @@ gss_cred_id_t *		d_cred;
 	     * then call gss_import_name() to create
 	     * the union name struct cast to src_name
 	     */
-	    if (internal_name != NULL) {
-		temp_status = gssint_convert_name_to_union_name(
-		       &temp_minor_status, mech,
-		       internal_name, &tmp_src_name);
-		if (temp_status != GSS_S_COMPLETE) {
-		    *minor_status = temp_minor_status;
-		    map_error(minor_status, mech);
-		    if (output_token->length)
-			(void) gss_release_buffer(&temp_minor_status,
-						  output_token);
-		    if (internal_name != GSS_C_NO_NAME)
-			mech->gss_release_name(
-			    &temp_minor_status,
-			    &internal_name);
-		    return (temp_status);
-		}
-		if (src_name != NULL) {
+	    if (src_name != NULL) {
+		if (internal_name != GSS_C_NO_NAME) {
+		    /* consumes internal_name regardless of success */
+		    temp_status = gssint_convert_name_to_union_name(
+			    &temp_minor_status, mech,
+			    internal_name, &tmp_src_name);
+		    if (temp_status != GSS_S_COMPLETE) {
+			*minor_status = temp_minor_status;
+			map_error(minor_status, mech);
+			if (output_token->length)
+			    (void) gss_release_buffer(&temp_minor_status,
+						      output_token);
+			return (temp_status);
+		    }
 		    *src_name = tmp_src_name;
-		}
-	    } else if (src_name != NULL) {
-		*src_name = GSS_C_NO_NAME;
+		} else
+		    *src_name = GSS_C_NO_NAME;
 	    }
 
+#define g_OID_prefix_equal(o1, o2) \
+        (((o1)->length >= (o2)->length) && \
+        (memcmp((o1)->elements, (o2)->elements, (o2)->length) == 0))
+
 	    /* Ensure we're returning correct creds format */
 	    if ((temp_ret_flags & GSS_C_DELEG_FLAG) &&
 		tmp_d_cred != GSS_C_NO_CREDENTIAL) {
-		gss_union_cred_t d_u_cred = NULL;
-
-		d_u_cred = malloc(sizeof (gss_union_cred_desc));
-		if (d_u_cred == NULL) {
-		    status = GSS_S_FAILURE;
-		    goto error_out;
-		}
-		(void) memset(d_u_cred, 0,
-			      sizeof (gss_union_cred_desc));
-
-		d_u_cred->count = 1;
+		if (actual_mech != GSS_C_NO_OID &&
+		    !g_OID_prefix_equal(actual_mech, token_mech_type)) {
+		    *d_cred = tmp_d_cred; /* unwrapped pseudo-mech */
+		} else {
+		    gss_union_cred_t d_u_cred = NULL;
 
-		status = generic_gss_copy_oid(&temp_minor_status,
-					      token_mech_type,
-					      &d_u_cred->mechs_array);
+		    d_u_cred = malloc(sizeof (gss_union_cred_desc));
+		    if (d_u_cred == NULL) {
+			status = GSS_S_FAILURE;
+			goto error_out;
+		    }
+		    (void) memset(d_u_cred, 0, sizeof (gss_union_cred_desc));
 
-		if (status != GSS_S_COMPLETE) {
-		    free(d_u_cred);
-		    goto error_out;
-		}
+		    d_u_cred->count = 1;
 
-		d_u_cred->cred_array = malloc(sizeof (gss_cred_id_t));
-		if (d_u_cred->cred_array != NULL) {
-		    d_u_cred->cred_array[0] = tmp_d_cred;
-		} else {
-		    free(d_u_cred);
-		    status = GSS_S_FAILURE;
-		    goto error_out;
-		}
+		    status = generic_gss_copy_oid(&temp_minor_status,
+						  token_mech_type,
+						  &d_u_cred->mechs_array);
 
-		internal_name = GSS_C_NO_NAME;
+		    if (status != GSS_S_COMPLETE) {
+			free(d_u_cred);
+			goto error_out;
+		    }
 
-		d_u_cred->auxinfo.creation_time = time(0);
-		d_u_cred->auxinfo.time_rec = 0;
-		d_u_cred->loopback = d_u_cred;
+		    d_u_cred->cred_array = malloc(sizeof(gss_cred_id_t));
+		    if (d_u_cred->cred_array != NULL) {
+			d_u_cred->cred_array[0] = tmp_d_cred;
+		    } else {
+			free(d_u_cred);
+			status = GSS_S_FAILURE;
+			goto error_out;
+		    }
 
-		if (mech->gss_inquire_cred) {
-		    status = mech->gss_inquire_cred(minor_status,
-						    tmp_d_cred,
-						    &internal_name,
-						    &d_u_cred->auxinfo.time_rec,
-						    &d_u_cred->auxinfo.cred_usage,
-						    NULL);
-		    if (status != GSS_S_COMPLETE)
-			map_error(minor_status, mech);
-		}
+		    d_u_cred->auxinfo.creation_time = time(0);
+		    d_u_cred->auxinfo.time_rec = 0;
+		    d_u_cred->loopback = d_u_cred;
+
+		    internal_name = GSS_C_NO_NAME;
+
+		    if (mech->gss_inquire_cred) {
+			status = mech->gss_inquire_cred(minor_status,
+							tmp_d_cred,
+							&internal_name,
+							&d_u_cred->auxinfo.time_rec,
+							&d_u_cred->auxinfo.cred_usage,
+							NULL);
+			if (status != GSS_S_COMPLETE)
+			    map_error(minor_status, mech);
+		    }
 
-		if (internal_name != NULL) {
-		    temp_status = gssint_convert_name_to_union_name(
-			&temp_minor_status, mech,
-			internal_name, &tmp_src_name);
-		    if (temp_status != GSS_S_COMPLETE) {
-			*minor_status = temp_minor_status;
-			map_error(minor_status, mech);
-			if (output_token->length)
-			    (void) gss_release_buffer(
+		    if (internal_name != GSS_C_NO_NAME) {
+			/* consumes internal_name regardless of success */
+			temp_status = gssint_convert_name_to_union_name(
+			    &temp_minor_status, mech,
+			    internal_name, &tmp_src_name);
+			if (temp_status != GSS_S_COMPLETE) {
+			    *minor_status = temp_minor_status;
+			    map_error(minor_status, mech);
+			    if (output_token->length)
+				(void) gss_release_buffer(
+				    &temp_minor_status,
+				    output_token);
+			    (void) gss_release_oid(&temp_minor_status,
+						   &actual_mech);
+			    free(d_u_cred->cred_array);
+			    free(d_u_cred);
+			    return (temp_status);
+			}
+
+			if (tmp_src_name != GSS_C_NO_NAME) {
+			    status = gss_display_name(
 				&temp_minor_status,
-				output_token);
-			free(d_u_cred->cred_array);
-			free(d_u_cred);
-			return (temp_status);
+				tmp_src_name,
+				&d_u_cred->auxinfo.name,
+				&d_u_cred->auxinfo.name_type);
+			    (void) gss_release_name(&temp_minor_status,
+						    &tmp_src_name);
+			}
 		    }
-		}
 
-		if (tmp_src_name != NULL) {
-		    status = gss_display_name(
-			&temp_minor_status,
-			tmp_src_name,
-			&d_u_cred->auxinfo.name,
-			&d_u_cred->auxinfo.name_type);
+		    *d_cred = (gss_cred_id_t)d_u_cred;
 		}
-
-		*d_cred = (gss_cred_id_t)d_u_cred;
 	    }
 
-	    if (src_name == NULL && tmp_src_name != NULL)
-		(void) gss_release_name(&temp_minor_status,
-					&tmp_src_name);
+	    if (mech_type != NULL)
+		*mech_type = actual_mech;
+	    else
+		(void) gss_release_oid(&temp_minor_status, &actual_mech);
 	    if (ret_flags != NULL)
 		*ret_flags = temp_ret_flags;
 	    return	(status);
diff --git a/src/lib/gssapi/mechglue/g_acquire_cred.c b/src/lib/gssapi/mechglue/g_acquire_cred.c
index fada9e887..6dfc65f7b 100644
--- a/src/lib/gssapi/mechglue/g_acquire_cred.c
+++ b/src/lib/gssapi/mechglue/g_acquire_cred.c
@@ -2,7 +2,7 @@
 
 /*
  * Copyright 1996 by Sun Microsystems, Inc.
- * 
+ *
  * Permission to use, copy, modify, distribute, and sell this software
  * and its documentation for any purpose is hereby granted without fee,
  * provided that the above copyright notice appears in all copies and
@@ -12,7 +12,7 @@
  * without specific, written prior permission. Sun Microsystems makes no
  * representations about the suitability of this software for any
  * purpose.  It is provided "as is" without express or implied warranty.
- * 
+ *
  * SUN MICROSYSTEMS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
  * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
  * EVENT SHALL SUN MICROSYSTEMS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
@@ -35,42 +35,6 @@
 #include <errno.h>
 #include <time.h>
 
-static gss_OID_set
-create_actual_mechs(mechs_array, count)
-    const gss_OID	mechs_array;
-    int count;
-{
-    gss_OID_set 	actual_mechs;
-    int			i;
-    OM_uint32		minor;
-
-    actual_mechs = (gss_OID_set) malloc(sizeof(gss_OID_set_desc));
-    if (!actual_mechs)
-	return NULL;
-
-    actual_mechs->elements = (gss_OID)
-	malloc(sizeof (gss_OID_desc) * count);
-    if (!actual_mechs->elements) {
-	free(actual_mechs);
-	return NULL;
-    }
-    
-    actual_mechs->count = 0;
-
-    for (i = 0; i < count; i++) {
-	actual_mechs->elements[i].elements = (void *)
-	    malloc(mechs_array[i].length);
-	if (actual_mechs->elements[i].elements == NULL) {
-	    (void) gss_release_oid_set(&minor, &actual_mechs);
-	    return (NULL);
-	}
-	g_OID_copy(&actual_mechs->elements[i], &mechs_array[i]);
-	actual_mechs->count++;
-    }
-
-    return actual_mechs;
-}
-
 static OM_uint32
 val_acq_cred_args(
     OM_uint32 *minor_status,
@@ -172,7 +136,7 @@ OM_uint32 *		time_rec;
 	mech = gssint_get_mechanism(NULL);
 	if (mech == NULL)
 	    return (GSS_S_BAD_MECH);
-	
+
 	mechs = &default_OID_set;
 	default_OID_set.count = 1;
 	default_OID_set.elements = &default_OID;
@@ -234,12 +198,16 @@ OM_uint32 *		time_rec;
      * setup the actual mechs output parameter
      */
     if (actual_mechs != NULL) {
-	if ((*actual_mechs = create_actual_mechs(creds->mechs_array,
-						 creds->count)) == NULL) {
+	gss_OID_set_desc oids;
+
+	oids.count = creds->count;
+	oids.elements = creds->mechs_array;
+
+	major = generic_gss_copy_oid_set(minor_status, &oids, actual_mechs);
+	if (GSS_ERROR(major)) {
 	    (void) gss_release_cred(minor_status,
 				    (gss_cred_id_t *)&creds);
-	    *minor_status = 0;
-	    return (GSS_S_FAILURE);
+	    return (major);
 	}
     }
 
@@ -312,7 +280,7 @@ OM_uint32 KRB5_CALLCONV
 gss_add_cred(minor_status, input_cred_handle,
 		  desired_name, desired_mech, cred_usage,
 		  initiator_time_req, acceptor_time_req,
-		  output_cred_handle, actual_mechs, 
+		  output_cred_handle, actual_mechs,
 		  initiator_time_rec, acceptor_time_rec)
     OM_uint32		*minor_status;
     gss_cred_id_t	input_cred_handle;
@@ -434,7 +402,7 @@ gss_add_cred(minor_status, input_cred_handle,
 	    status = mech->gss_display_name(&temp_minor_status, internal_name,
 					    &union_cred->auxinfo.name,
 					    &union_cred->auxinfo.name_type);
-	
+
 	    if (status != GSS_S_COMPLETE)
 		goto errout;
 	}
@@ -475,10 +443,14 @@ gss_add_cred(minor_status, input_cred_handle,
     g_OID_copy(&new_mechs_array[union_cred->count],
 	       &mech->mech_type);
 
-    if (actual_mechs) {
-	*actual_mechs = create_actual_mechs(new_mechs_array,
-					    union_cred->count + 1);
-	if (*actual_mechs == NULL) {
+    if (actual_mechs != NULL) {
+	gss_OID_set_desc oids;
+
+	oids.count = union_cred->count + 1;
+	oids.elements = new_mechs_array;
+
+	status = generic_gss_copy_oid_set(minor_status, &oids, actual_mechs);
+	if (GSS_ERROR(status)) {
 	    free(new_mechs_array[union_cred->count].elements);
 	    goto errout;
 	}
diff --git a/src/lib/gssapi/mechglue/g_acquire_cred_imp_name.c b/src/lib/gssapi/mechglue/g_acquire_cred_imp_name.c
new file mode 100644
index 000000000..9ba6a1faa
--- /dev/null
+++ b/src/lib/gssapi/mechglue/g_acquire_cred_imp_name.c
@@ -0,0 +1,549 @@
+/* #pragma ident	"@(#)g_acquire_cred.c	1.22	04/02/23 SMI" */
+
+/*
+ * Copyright 2009 by the Massachusetts Institute of Technology.
+ * All Rights Reserved.
+ *
+ * Export of this software from the United States of America may
+ *   require a specific license from the United States Government.
+ *   It is the responsibility of any person or organization contemplating
+ *   export to obtain such a license before exporting.
+ *
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of M.I.T. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission.  Furthermore if you modify this software you must label
+ * your software as modified software and not distribute it in such a
+ * fashion that it might be confused with the original M.I.T. software.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is" without express
+ * or implied warranty.
+ *
+ */
+/*
+ * Copyright 1996 by Sun Microsystems, Inc.
+ *
+ * Permission to use, copy, modify, distribute, and sell this software
+ * and its documentation for any purpose is hereby granted without fee,
+ * provided that the above copyright notice appears in all copies and
+ * that both that copyright notice and this permission notice appear in
+ * supporting documentation, and that the name of Sun Microsystems not be used
+ * in advertising or publicity pertaining to distribution of the software
+ * without specific, written prior permission. Sun Microsystems makes no
+ * representations about the suitability of this software for any
+ * purpose.  It is provided "as is" without express or implied warranty.
+ *
+ * SUN MICROSYSTEMS DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL SUN MICROSYSTEMS BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF
+ * USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+ * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+/*
+ *  glue routine for gss_acquire_cred_impersonate_name
+ */
+
+#include "mglueP.h"
+#include <stdio.h>
+#ifdef HAVE_STDLIB_H
+#include <stdlib.h>
+#endif
+#include <string.h>
+#include <errno.h>
+#include <time.h>
+
+static OM_uint32
+val_acq_cred_impersonate_name_args(
+    OM_uint32 *minor_status,
+    const gss_cred_id_t impersonator_cred_handle,
+    const gss_name_t desired_name,
+    OM_uint32 time_req,
+    gss_OID_set desired_mechs,
+    gss_cred_usage_t cred_usage,
+    gss_cred_id_t *output_cred_handle,
+    gss_OID_set *actual_mechs,
+    OM_uint32 *time_rec)
+{
+
+    /* Initialize outputs. */
+
+    if (minor_status != NULL)
+	*minor_status = 0;
+
+    if (output_cred_handle != NULL)
+	*output_cred_handle = GSS_C_NO_CREDENTIAL;
+
+    if (actual_mechs != NULL)
+	*actual_mechs = GSS_C_NULL_OID_SET;
+
+    if (time_rec != NULL)
+	*time_rec = 0;
+
+    /* Validate arguments. */
+
+    if (minor_status == NULL)
+	return (GSS_S_CALL_INACCESSIBLE_WRITE);
+
+    if (impersonator_cred_handle == GSS_C_NO_CREDENTIAL)
+	return (GSS_S_CALL_INACCESSIBLE_READ | GSS_S_NO_CRED);
+
+    if (desired_name == GSS_C_NO_NAME)
+	return (GSS_S_CALL_INACCESSIBLE_READ | GSS_S_BAD_NAME);
+
+    if (output_cred_handle == NULL)
+	return (GSS_S_CALL_INACCESSIBLE_WRITE);
+
+    if (cred_usage != GSS_C_ACCEPT
+	&& cred_usage != GSS_C_INITIATE
+	&& cred_usage != GSS_C_BOTH) {
+	if (minor_status) {
+	    *minor_status = EINVAL;
+	    map_errcode(minor_status);
+	}
+	return GSS_S_FAILURE;
+    }
+
+    return (GSS_S_COMPLETE);
+}
+
+
+OM_uint32 KRB5_CALLCONV
+gss_acquire_cred_impersonate_name(OM_uint32 *minor_status,
+				  const gss_cred_id_t impersonator_cred_handle,
+				  const gss_name_t desired_name,
+				  OM_uint32 time_req,
+				  const gss_OID_set desired_mechs,
+				  gss_cred_usage_t cred_usage,
+				  gss_cred_id_t *output_cred_handle,
+				  gss_OID_set *actual_mechs,
+				  OM_uint32 *time_rec)
+{
+    OM_uint32 major = GSS_S_FAILURE;
+    OM_uint32 initTimeOut, acceptTimeOut, outTime = GSS_C_INDEFINITE;
+    gss_OID_set_desc default_OID_set;
+    gss_OID_set mechs;
+    gss_OID_desc default_OID;
+    gss_mechanism mech;
+    unsigned int i;
+    gss_union_cred_t creds;
+
+    major = val_acq_cred_impersonate_name_args(minor_status,
+					       impersonator_cred_handle,
+					       desired_name,
+					       time_req,
+					       desired_mechs,
+					       cred_usage,
+					       output_cred_handle,
+					       actual_mechs,
+					       time_rec);
+    if (major != GSS_S_COMPLETE)
+	return (major);
+
+    /* Initial value needed below. */
+    major = GSS_S_FAILURE;
+
+    /*
+     * if desired_mechs equals GSS_C_NULL_OID_SET, then pick an
+     * appropriate default.  We use the first mechanism in the
+     * mechansim list as the default. This set is created with
+     * statics thus needs not be freed
+     */
+    if(desired_mechs == GSS_C_NULL_OID_SET) {
+	mech = gssint_get_mechanism(NULL);
+	if (mech == NULL)
+	    return (GSS_S_BAD_MECH);
+
+	mechs = &default_OID_set;
+	default_OID_set.count = 1;
+	default_OID_set.elements = &default_OID;
+	default_OID.length = mech->mech_type.length;
+	default_OID.elements = mech->mech_type.elements;
+    } else
+	mechs = desired_mechs;
+
+    if (mechs->count == 0)
+	return (GSS_S_BAD_MECH);
+
+    /* allocate the output credential structure */
+    creds = (gss_union_cred_t)malloc(sizeof (gss_union_cred_desc));
+    if (creds == NULL)
+	return (GSS_S_FAILURE);
+
+    /* initialize to 0s */
+    (void) memset(creds, 0, sizeof (gss_union_cred_desc));
+    creds->loopback = creds;
+
+    /* for each requested mech attempt to obtain a credential */
+    for (i = 0; i < mechs->count; i++) {
+	major = gss_add_cred_impersonate_name(minor_status,
+					      (gss_cred_id_t)creds,
+					      impersonator_cred_handle,
+					      desired_name,
+					      &mechs->elements[i],
+					      cred_usage,
+					      time_req,
+					      time_req, NULL,
+					      NULL,
+					      &initTimeOut,
+					      &acceptTimeOut);
+	if (major == GSS_S_COMPLETE) {
+	    /* update the credential's time */
+	    if (cred_usage == GSS_C_ACCEPT) {
+		if (outTime > acceptTimeOut)
+		    outTime = acceptTimeOut;
+	    } else if (cred_usage == GSS_C_INITIATE) {
+		if (outTime > initTimeOut)
+		    outTime = initTimeOut;
+	    } else {
+		/*
+		 * time_rec is the lesser of the
+		 * init/accept times
+		 */
+		if (initTimeOut > acceptTimeOut)
+		    outTime = (outTime > acceptTimeOut) ?
+			acceptTimeOut : outTime;
+		else
+		    outTime = (outTime > initTimeOut) ?
+			initTimeOut : outTime;
+	    }
+	}
+    } /* for */
+
+    /* ensure that we have at least one credential element */
+    if (creds->count < 1) {
+	free(creds);
+	return (major);
+    }
+
+    /*
+     * fill in output parameters
+     * setup the actual mechs output parameter
+     */
+    if (actual_mechs != NULL) {
+	gss_OID_set_desc oids;
+
+	oids.count = creds->count;
+	oids.elements = creds->mechs_array;
+
+	major = generic_gss_copy_oid_set(minor_status, &oids, actual_mechs);
+	if (GSS_ERROR(major)) {
+	    (void) gss_release_cred(minor_status,
+				    (gss_cred_id_t *)&creds);
+	    return (major);
+	}
+    }
+
+    if (time_rec)
+	*time_rec = outTime;
+
+
+    creds->loopback = creds;
+    *output_cred_handle = (gss_cred_id_t)creds;
+    return (GSS_S_COMPLETE);
+}
+
+static OM_uint32
+val_add_cred_impersonate_name_args(
+    OM_uint32 *minor_status,
+    gss_cred_id_t input_cred_handle,
+    const gss_cred_id_t impersonator_cred_handle,
+    gss_name_t desired_name,
+    gss_OID desired_mech,
+    gss_cred_usage_t cred_usage,
+    OM_uint32 initiator_time_req,
+    OM_uint32 acceptor_time_req,
+    gss_cred_id_t *output_cred_handle,
+    gss_OID_set *actual_mechs,
+    OM_uint32 *initiator_time_rec,
+    OM_uint32 *acceptor_time_rec)
+{
+
+    /* Initialize outputs. */
+
+    if (minor_status != NULL)
+	*minor_status = 0;
+
+    if (output_cred_handle != NULL)
+	*output_cred_handle = GSS_C_NO_CREDENTIAL;
+
+    if (actual_mechs != NULL)
+	*actual_mechs = GSS_C_NO_OID_SET;
+
+    if (acceptor_time_rec != NULL)
+	*acceptor_time_rec = 0;
+
+    if (initiator_time_rec != NULL)
+	*initiator_time_rec = 0;
+
+    /* Validate arguments. */
+
+    if (minor_status == NULL)
+	return (GSS_S_CALL_INACCESSIBLE_WRITE);
+
+    if (impersonator_cred_handle == GSS_C_NO_CREDENTIAL)
+	return (GSS_S_CALL_INACCESSIBLE_READ | GSS_S_NO_CRED);
+
+    if (desired_name == GSS_C_NO_NAME)
+	return (GSS_S_CALL_INACCESSIBLE_READ | GSS_S_BAD_NAME);
+
+    if (input_cred_handle == GSS_C_NO_CREDENTIAL &&
+	output_cred_handle == NULL)
+	return (GSS_S_CALL_INACCESSIBLE_WRITE | GSS_S_NO_CRED);
+
+    if (cred_usage != GSS_C_ACCEPT
+	&& cred_usage != GSS_C_INITIATE
+	&& cred_usage != GSS_C_BOTH) {
+	if (minor_status) {
+	    *minor_status = EINVAL;
+	    map_errcode(minor_status);
+	}
+	return GSS_S_FAILURE;
+    }
+
+    return (GSS_S_COMPLETE);
+}
+
+
+/* V2 KRB5_CALLCONV */
+OM_uint32 KRB5_CALLCONV
+gss_add_cred_impersonate_name(OM_uint32 *minor_status,
+			      gss_cred_id_t input_cred_handle,
+			      const gss_cred_id_t impersonator_cred_handle,
+			      const gss_name_t desired_name,
+			      const gss_OID desired_mech,
+			      gss_cred_usage_t cred_usage,
+			      OM_uint32 initiator_time_req,
+			      OM_uint32 acceptor_time_req,
+			      gss_cred_id_t *output_cred_handle,
+			      gss_OID_set *actual_mechs,
+			      OM_uint32 *initiator_time_rec,
+			      OM_uint32 *acceptor_time_rec)
+{
+    OM_uint32		status, temp_minor_status;
+    OM_uint32		time_req, time_rec;
+    gss_union_name_t	union_name;
+    gss_union_cred_t	new_union_cred, union_cred;
+    gss_cred_id_t	mech_impersonator_cred;
+    gss_name_t		internal_name = GSS_C_NO_NAME;
+    gss_name_t		allocated_name = GSS_C_NO_NAME;
+    gss_mechanism	mech;
+    gss_cred_id_t	cred = NULL;
+    gss_OID		new_mechs_array = NULL;
+    gss_cred_id_t *	new_cred_array = NULL;
+
+    status = val_add_cred_impersonate_name_args(minor_status,
+						input_cred_handle,
+						impersonator_cred_handle,
+						desired_name,
+						desired_mech,
+						cred_usage,
+						initiator_time_req,
+						acceptor_time_req,
+						output_cred_handle,
+						actual_mechs,
+						initiator_time_rec,
+						acceptor_time_rec);
+    if (status != GSS_S_COMPLETE)
+	return (status);
+
+    mech = gssint_get_mechanism(desired_mech);
+    if (!mech)
+	return GSS_S_BAD_MECH;
+    else if (!mech->gss_acquire_cred)
+	return (GSS_S_UNAVAILABLE);
+
+    if (input_cred_handle == GSS_C_NO_CREDENTIAL) {
+	union_cred = malloc(sizeof (gss_union_cred_desc));
+	if (union_cred == NULL)
+	    return (GSS_S_FAILURE);
+
+	(void) memset(union_cred, 0, sizeof (gss_union_cred_desc));
+
+	/* for default credentials we will use GSS_C_NO_NAME */
+	internal_name = GSS_C_NO_NAME;
+    } else {
+	union_cred = (gss_union_cred_t)input_cred_handle;
+	if (gssint_get_mechanism_cred(union_cred, desired_mech) !=
+	    GSS_C_NO_CREDENTIAL)
+	    return (GSS_S_DUPLICATE_ELEMENT);
+    }
+
+    mech_impersonator_cred =
+	gssint_get_mechanism_cred((gss_union_cred_t)impersonator_cred_handle,
+				  desired_mech);
+    if (mech_impersonator_cred == GSS_C_NO_CREDENTIAL)
+	return (GSS_S_NO_CRED);
+
+    /* may need to create a mechanism specific name */
+    union_name = (gss_union_name_t)desired_name;
+    if (union_name->mech_type &&
+	g_OID_equal(union_name->mech_type,
+		    &mech->mech_type))
+	internal_name = union_name->mech_name;
+    else {
+	if (gssint_import_internal_name(minor_status,
+				        &mech->mech_type, union_name,
+				        &allocated_name) != GSS_S_COMPLETE)
+	    return (GSS_S_BAD_NAME);
+	internal_name = allocated_name;
+    }
+
+    if (cred_usage == GSS_C_ACCEPT)
+	time_req = acceptor_time_req;
+    else if (cred_usage == GSS_C_INITIATE)
+	time_req = initiator_time_req;
+    else if (cred_usage == GSS_C_BOTH)
+	time_req = (acceptor_time_req > initiator_time_req) ?
+	    acceptor_time_req : initiator_time_req;
+    else
+	time_req = 0;
+
+    status = mech->gss_acquire_cred_impersonate_name(minor_status,
+						     mech_impersonator_cred,
+						     internal_name,
+						     time_req,
+						     GSS_C_NULL_OID_SET,
+						     cred_usage,
+						     &cred,
+						     NULL,
+						     &time_rec);
+    if (status != GSS_S_COMPLETE) {
+	map_error(minor_status, mech);
+	goto errout;
+    }
+
+    /* may need to set credential auxinfo strucutre */
+    if (union_cred->auxinfo.creation_time == 0) {
+	union_cred->auxinfo.creation_time = time(NULL);
+	union_cred->auxinfo.time_rec = time_rec;
+	union_cred->auxinfo.cred_usage = cred_usage;
+
+	/*
+	 * we must set the name; if name is not supplied
+	 * we must do inquire cred to get it
+	 */
+	if (internal_name == NULL) {
+	    if (mech->gss_inquire_cred == NULL ||
+		((status = mech->gss_inquire_cred(
+		      &temp_minor_status, cred,
+		      &allocated_name, NULL, NULL,
+		      NULL)) != GSS_S_COMPLETE))
+		goto errout;
+	    internal_name = allocated_name;
+	}
+
+	if (internal_name != GSS_C_NO_NAME) {
+	    status = mech->gss_display_name(&temp_minor_status, internal_name,
+					    &union_cred->auxinfo.name,
+					    &union_cred->auxinfo.name_type);
+
+	    if (status != GSS_S_COMPLETE)
+		goto errout;
+	}
+    }
+
+    /* now add the new credential elements */
+    new_mechs_array = (gss_OID)
+	malloc(sizeof (gss_OID_desc) * (union_cred->count+1));
+
+    new_cred_array = (gss_cred_id_t *)
+	malloc(sizeof (gss_cred_id_t) * (union_cred->count+1));
+
+    if (!new_mechs_array || !new_cred_array) {
+	status = GSS_S_FAILURE;
+	goto errout;
+    }
+
+    if (acceptor_time_rec)
+	if (cred_usage == GSS_C_ACCEPT || cred_usage == GSS_C_BOTH)
+	    *acceptor_time_rec = time_rec;
+    if (initiator_time_rec)
+	if (cred_usage == GSS_C_INITIATE || cred_usage == GSS_C_BOTH)
+	    *initiator_time_rec = time_rec;
+
+    /*
+     * OK, expand the mechanism array and the credential array
+     */
+    (void) memcpy(new_mechs_array, union_cred->mechs_array,
+		  sizeof (gss_OID_desc) * union_cred->count);
+    (void) memcpy(new_cred_array, union_cred->cred_array,
+		  sizeof (gss_cred_id_t) * union_cred->count);
+
+    new_cred_array[union_cred->count] = cred;
+    if ((new_mechs_array[union_cred->count].elements =
+	 malloc(mech->mech_type.length)) == NULL)
+	goto errout;
+
+    g_OID_copy(&new_mechs_array[union_cred->count],
+	       &mech->mech_type);
+
+    if (actual_mechs != NULL) {
+	gss_OID_set_desc oids;
+
+	oids.count = union_cred->count + 1;
+	oids.elements = new_mechs_array;
+
+	status = generic_gss_copy_oid_set(minor_status, &oids, actual_mechs);
+	if (GSS_ERROR(status)) {
+	    free(new_mechs_array[union_cred->count].elements);
+	    goto errout;
+	}
+    }
+
+    if (output_cred_handle == NULL) {
+	free(union_cred->mechs_array);
+	free(union_cred->cred_array);
+	new_union_cred = union_cred;
+    } else {
+	new_union_cred = malloc(sizeof (gss_union_cred_desc));
+	if (new_union_cred == NULL) {
+	    free(new_mechs_array[union_cred->count].elements);
+	    goto errout;
+	}
+	*new_union_cred = *union_cred;
+	*output_cred_handle = (gss_cred_id_t)new_union_cred;
+    }
+
+    new_union_cred->mechs_array = new_mechs_array;
+    new_union_cred->cred_array = new_cred_array;
+    new_union_cred->count++;
+    new_union_cred->loopback = new_union_cred;
+
+    /* We're done with the internal name. Free it if we allocated it. */
+
+    if (allocated_name)
+	(void) gssint_release_internal_name(&temp_minor_status,
+					   &mech->mech_type,
+					   &allocated_name);
+
+    return (GSS_S_COMPLETE);
+
+errout:
+    if (new_mechs_array)
+	free(new_mechs_array);
+    if (new_cred_array)
+	free(new_cred_array);
+
+    if (cred != NULL && mech->gss_release_cred)
+	mech->gss_release_cred(&temp_minor_status, &cred);
+
+    if (allocated_name)
+	(void) gssint_release_internal_name(&temp_minor_status,
+					   &mech->mech_type,
+					   &allocated_name);
+
+    if (input_cred_handle == GSS_C_NO_CREDENTIAL && union_cred) {
+	if (union_cred->auxinfo.name.value)
+	    free(union_cred->auxinfo.name.value);
+	free(union_cred);
+    }
+
+    return (status);
+}
diff --git a/src/lib/gssapi/mechglue/g_glue.c b/src/lib/gssapi/mechglue/g_glue.c
index 5a8ea54b1..4d35819c5 100644
--- a/src/lib/gssapi/mechglue/g_glue.c
+++ b/src/lib/gssapi/mechglue/g_glue.c
@@ -611,25 +611,9 @@ gssint_get_mechanism_cred(union_cred, mech_type)
     if (union_cred == GSS_C_NO_CREDENTIAL)
 	return GSS_C_NO_CREDENTIAL;
 
-    /* SPNEGO mechanism will again call into GSSAPI */
-    if (g_OID_equal(&gss_spnego_mechanism_oid_desc, mech_type))
-	return (gss_cred_id_t)union_cred;
-
     for (i=0; i < union_cred->count; i++) {
 	if (g_OID_equal(mech_type, &union_cred->mechs_array[i]))
 	    return union_cred->cred_array[i];
-
-	/* for SPNEGO, check the next-lower set of creds */
-	if (g_OID_equal(&gss_spnego_mechanism_oid_desc, &union_cred->mechs_array[i])) {
-	    gss_union_cred_t candidate_cred;
-	    gss_cred_id_t    sub_cred;
-
-	    candidate_cred = (gss_union_cred_t)union_cred->cred_array[i];
-	    sub_cred = gssint_get_mechanism_cred(candidate_cred, mech_type);
-
-	    if(sub_cred != GSS_C_NO_CREDENTIAL)
-		return sub_cred;
-	}
     }
     return GSS_C_NO_CREDENTIAL;
 }
diff --git a/src/lib/gssapi/mechglue/g_initialize.c b/src/lib/gssapi/mechglue/g_initialize.c
index 85fbe6321..e34b7bf0a 100644
--- a/src/lib/gssapi/mechglue/g_initialize.c
+++ b/src/lib/gssapi/mechglue/g_initialize.c
@@ -761,6 +761,9 @@ build_dynamicMech(void *dl, const gss_OID mech_type)
 	GSS_ADD_DYNAMIC_METHOD(dl, mech, gss_unwrap_iov);
 	GSS_ADD_DYNAMIC_METHOD(dl, mech, gss_wrap_iov_length);
 	GSS_ADD_DYNAMIC_METHOD(dl, mech, gss_complete_auth_token);
+	/* New for 1.8 */
+	GSS_ADD_DYNAMIC_METHOD(dl, mech, gss_acquire_cred_impersonate_name);
+	GSS_ADD_DYNAMIC_METHOD(dl, mech, gss_add_cred_impersonate_name);
 
 	assert(mech_type != GSS_C_NO_OID);
 
diff --git a/src/lib/gssapi/mechglue/g_set_context_option.c b/src/lib/gssapi/mechglue/g_set_context_option.c
index 17d9e3bac..b35b36ad5 100644
--- a/src/lib/gssapi/mechglue/g_set_context_option.c
+++ b/src/lib/gssapi/mechglue/g_set_context_option.c
@@ -70,8 +70,8 @@ gss_set_sec_context_option (OM_uint32 *minor_status,
     }
 
     status = mech->gss_set_sec_context_option(minor_status,
-					      ctx ? &internal_ctx :
-						&ctx->internal_ctx_id,
+					      ctx ? &ctx->internal_ctx_id :
+					      &internal_ctx,
 					      desired_object,
 					      value);
     if (status == GSS_S_COMPLETE) {
diff --git a/src/lib/gssapi/mechglue/mglueP.h b/src/lib/gssapi/mechglue/mglueP.h
index 001636146..46bfb9463 100644
--- a/src/lib/gssapi/mechglue/mglueP.h
+++ b/src/lib/gssapi/mechglue/mglueP.h
@@ -473,6 +473,37 @@ typedef struct gss_config {
     		    gss_buffer_t	/* input_message_buffer */
     		    );
 
+	/* New for 1.8 */
+
+	OM_uint32	(*gss_acquire_cred_impersonate_name)
+	(
+	    OM_uint32 *,		/* minor_status */
+	    const gss_cred_id_t,	/* impersonator_cred_handle */
+	    const gss_name_t,		/* desired_name */
+	    OM_uint32,			/* time_req */
+	    const gss_OID_set,		/* desired_mechs */
+	    gss_cred_usage_t,		/* cred_usage */
+	    gss_cred_id_t *,		/* output_cred_handle */
+	    gss_OID_set *,		/* actual_mechs */
+	    OM_uint32 *			/* time_rec */
+	/* */);
+
+	OM_uint32	(*gss_add_cred_impersonate_name)
+	(
+	    OM_uint32 *,		/* minor_status */
+	    gss_cred_id_t,		/* input_cred_handle */
+	    const gss_cred_id_t,	/* impersonator_cred_handle */
+	    const gss_name_t,		/* desired_name */
+	    const gss_OID,		/* desired_mech */
+	    gss_cred_usage_t,		/* cred_usage */
+	    OM_uint32,			/* initiator_time_req */
+	    OM_uint32,			/* acceptor_time_req */
+	    gss_cred_id_t *,		/* output_cred_handle */
+	    gss_OID_set *,		/* actual_mechs */
+	    OM_uint32 *,		/* initiator_time_rec */
+	    OM_uint32 *			/* acceptor_time_rec */
+	/* */);
+
 } *gss_mechanism;
 
 /* This structure MUST NOT be used by any code outside libgss */
diff --git a/src/lib/gssapi/spnego/gssapiP_spnego.h b/src/lib/gssapi/spnego/gssapiP_spnego.h
index e1f3987cd..5e6cd5a0c 100644
--- a/src/lib/gssapi/spnego/gssapiP_spnego.h
+++ b/src/lib/gssapi/spnego/gssapiP_spnego.h
@@ -218,6 +218,16 @@ OM_uint32 spnego_gss_release_name
 	gss_name_t *		/* input_name */
 );
 
+OM_uint32 spnego_gss_inquire_cred
+(
+	OM_uint32 *,		/* minor_status */
+	gss_cred_id_t,		/* cred_handle */
+	gss_name_t *,		/* name */
+	OM_uint32 *,		/* lifetime */
+	int *,			/* cred_usage */
+	gss_OID_set *		/* mechanisms */
+);
+
 OM_uint32 spnego_gss_inquire_names_for_mech
 (
 	OM_uint32 *,		/* minor_status */
@@ -333,6 +343,15 @@ spnego_gss_inquire_sec_context_by_oid
 );
 
 OM_uint32
+spnego_gss_inquire_cred_by_oid
+(
+	OM_uint32 *minor_status,
+	const gss_cred_id_t cred_handle,
+	const gss_OID desired_object,
+	gss_buffer_set_t *data_set
+);
+
+OM_uint32
 spnego_gss_set_sec_context_option
 (
 	OM_uint32 *minor_status,
@@ -411,6 +430,18 @@ spnego_gss_complete_auth_token
 	gss_buffer_t input_message_buffer
 );
 
+OM_uint32
+spnego_gss_acquire_cred_impersonate_name(
+    OM_uint32 *,	    /* minor_status */
+    const gss_cred_id_t,    /* impersonator_cred_handle */
+    const gss_name_t,	    /* desired_name */
+    OM_uint32,		    /* time_req */
+    const gss_OID_set,	    /* desired_mechs */
+    gss_cred_usage_t,	    /* cred_usage */
+    gss_cred_id_t *,	    /* output_cred_handle */
+    gss_OID_set *,	    /* actual_mechs */
+    OM_uint32 *);	    /* time_rec */
+
 #ifdef	__cplusplus
 }
 #endif
diff --git a/src/lib/gssapi/spnego/spnego_mech.c b/src/lib/gssapi/spnego/spnego_mech.c
index a2b926dc3..14b65f751 100644
--- a/src/lib/gssapi/spnego/spnego_mech.c
+++ b/src/lib/gssapi/spnego/spnego_mech.c
@@ -231,7 +231,7 @@ static struct gss_config spnego_mechanism =
 	spnego_gss_display_name,
 	spnego_gss_import_name,
 	spnego_gss_release_name,
-	NULL,				/* gss_inquire_cred */
+	spnego_gss_inquire_cred,	/* gss_inquire_cred */
 	NULL,				/* gss_add_cred */
 #ifndef LEAN_CLIENT
 	spnego_gss_export_sec_context,		/* gss_export_sec_context */
@@ -248,7 +248,7 @@ static struct gss_config spnego_mechanism =
 	NULL,				/* gss_export_name */
 	NULL,				/* gss_store_cred */
  	spnego_gss_inquire_sec_context_by_oid, /* gss_inquire_sec_context_by_oid */
- 	NULL,				/* gss_inquire_cred_by_oid */
+ 	spnego_gss_inquire_cred_by_oid,	/* gss_inquire_cred_by_oid */
  	spnego_gss_set_sec_context_option, /* gss_set_sec_context_option */
  	NULL,				/* gssspi_set_cred_option */
  	NULL,				/* gssspi_mech_invoke */
@@ -257,7 +257,9 @@ static struct gss_config spnego_mechanism =
 	spnego_gss_wrap_iov,
 	spnego_gss_unwrap_iov,
 	spnego_gss_wrap_iov_length,
-	spnego_gss_complete_auth_token
+	spnego_gss_complete_auth_token,
+	spnego_gss_acquire_cred_impersonate_name,
+	NULL,				/* gss_add_cred_impersonate_name */
 };
 
 #ifdef _GSS_STATIC_LINK
@@ -1787,6 +1789,76 @@ spnego_gss_release_name(
 	return (status);
 }
 
+OM_uint32
+spnego_gss_inquire_cred(
+			OM_uint32 *minor_status,
+			gss_cred_id_t cred_handle,
+			gss_name_t *name,
+			OM_uint32 *lifetime,
+			int *cred_usage,
+			gss_OID_set *mechanisms)
+{
+	OM_uint32 status;
+	gss_cred_id_t creds = GSS_C_NO_CREDENTIAL;
+	OM_uint32 tmp_minor_status;
+	OM_uint32 initiator_lifetime, acceptor_lifetime;
+
+	dsyslog("Entering inquire_cred\n");
+
+	/*
+	 * To avoid infinite recursion, if GSS_C_NO_CREDENTIAL is
+	 * supplied we call gss_inquire_cred_by_mech() on the
+	 * first non-SPNEGO mechanism.
+	 */
+	if (cred_handle == GSS_C_NO_CREDENTIAL) {
+		status = get_available_mechs(minor_status,
+			GSS_C_NO_NAME,
+			GSS_C_BOTH,
+			&creds,
+			mechanisms);
+		if (status != GSS_S_COMPLETE) {
+			dsyslog("Leaving inquire_cred\n");
+			return (status);
+		}
+
+		if ((*mechanisms)->count == 0) {
+			gss_release_cred(&tmp_minor_status, &creds);
+			gss_release_oid_set(&tmp_minor_status, mechanisms);
+			dsyslog("Leaving inquire_cred\n");
+			return (GSS_S_DEFECTIVE_CREDENTIAL);
+		}
+
+		assert((*mechanisms)->elements != NULL);
+
+		status = gss_inquire_cred_by_mech(minor_status,
+			creds,
+			&(*mechanisms)->elements[0],
+			name,
+			&initiator_lifetime,
+			&acceptor_lifetime,
+			cred_usage);
+		if (status != GSS_S_COMPLETE) {
+			gss_release_cred(&tmp_minor_status, &creds);
+			dsyslog("Leaving inquire_cred\n");
+			return (status);
+		}
+
+		if (lifetime != NULL)
+			*lifetime = (*cred_usage == GSS_C_ACCEPT) ?
+				acceptor_lifetime : initiator_lifetime;
+
+		gss_release_cred(&tmp_minor_status, &creds);
+	} else {
+		status = gss_inquire_cred(minor_status, cred_handle,
+					  name, lifetime,
+					  cred_usage, mechanisms);
+	}
+
+	dsyslog("Leaving inquire_cred\n");
+
+	return (status);
+}
+
 /*ARGSUSED*/
 OM_uint32
 spnego_gss_compare_name(
@@ -1942,6 +2014,9 @@ spnego_gss_delete_sec_context(
 	 */
 	if (*ctx != NULL &&
 	    (*ctx)->magic_num == SPNEGO_MAGIC_ID) {
+		(void) gss_delete_sec_context(minor_status,
+				    &(*ctx)->ctx_handle,
+				    output_token);
 		(void) release_spnego_ctx(ctx);
 	} else {
 		ret = gss_delete_sec_context(minor_status,
@@ -2088,6 +2163,21 @@ spnego_gss_inquire_sec_context_by_oid(
 }
 
 OM_uint32
+spnego_gss_inquire_cred_by_oid(
+		OM_uint32 *minor_status,
+		const gss_cred_id_t cred_handle,
+		const gss_OID desired_object,
+		gss_buffer_set_t *data_set)
+{
+	OM_uint32 ret;
+	ret = gss_inquire_cred_by_oid(minor_status,
+				cred_handle,
+				desired_object,
+				data_set);
+	return (ret);
+}
+
+OM_uint32
 spnego_gss_set_sec_context_option(
 		OM_uint32 *minor_status,
 		gss_ctx_id_t *context_handle,
@@ -2217,6 +2307,53 @@ spnego_gss_complete_auth_token(
 	return (ret);
 }
 
+OM_uint32
+spnego_gss_acquire_cred_impersonate_name(OM_uint32 *minor_status,
+					 const gss_cred_id_t impersonator_cred_handle,
+					 gss_name_t desired_name,
+					 OM_uint32 time_req,
+					 gss_OID_set desired_mechs,
+					 gss_cred_usage_t cred_usage,
+					 gss_cred_id_t *output_cred_handle,
+					 gss_OID_set *actual_mechs,
+					 OM_uint32 *time_rec)
+{
+	OM_uint32 status;
+	gss_OID_set amechs = GSS_C_NULL_OID_SET;
+
+	dsyslog("Entering spnego_gss_acquire_cred_impersonate_name\n");
+
+	if (actual_mechs)
+		*actual_mechs = NULL;
+
+	if (time_rec)
+		*time_rec = 0;
+
+	if (desired_mechs == GSS_C_NO_OID_SET) {
+		status = gss_inquire_cred(minor_status,
+					  impersonator_cred_handle,
+					  NULL, NULL,
+					  NULL, &amechs);
+		if (status != GSS_S_COMPLETE)
+			return status;
+
+		desired_mechs = amechs;
+	}
+
+	status = gss_acquire_cred_impersonate_name(minor_status,
+			impersonator_cred_handle,
+			desired_name, time_req,
+			desired_mechs, cred_usage,
+			output_cred_handle, actual_mechs,
+			time_rec);
+
+	if (amechs != GSS_C_NULL_OID_SET)
+		(void) gss_release_oid_set(minor_status, &amechs);
+
+	dsyslog("Leaving spnego_gss_acquire_cred_impersonate_name\n");
+	return (status);
+}
+
 /*
  * We will release everything but the ctx_handle so that it
  * can be passed back to init/accept context. This routine should
diff --git a/src/lib/kadm5/str_conv.c b/src/lib/kadm5/str_conv.c
index 2bd99adbc..51637f7de 100644
--- a/src/lib/kadm5/str_conv.c
+++ b/src/lib/kadm5/str_conv.c
@@ -78,6 +78,8 @@ static const char flags_pwchange_in[]	= "pwchange";
 static const char flags_service_in[]	= "service";
 static const char flags_pwsvc_in[]	= "pwservice";
 static const char flags_md5_in[]	= "md5";
+static const char flags_ok_to_auth_as_delegate_in[] = "ok-to-auth-as-delegate";
+static const char flags_no_auth_data_required_in[] = "no-auth-data-required";
 static const char flags_pdate_out[]	= "Not Postdateable";
 static const char flags_fwd_out[]	= "Not Forwardable";
 static const char flags_tgtbased_out[]	= "No TGT-based requests";
@@ -85,13 +87,15 @@ static const char flags_renew_out[]	= "Not renewable";
 static const char flags_proxy_out[]	= "Not proxiable";
 static const char flags_dup_skey_out[]	= "No DUP_SKEY requests";
 static const char flags_tickets_out[]	= "All Tickets Disallowed";
-static const char flags_preauth_out[]	= "Preauthorization required";
-static const char flags_hwauth_out[]	= "HW Authorization required";
+static const char flags_preauth_out[]	= "Preauthentication required";
+static const char flags_hwauth_out[]	= "HW authentication required";
 static const char flags_ok_as_delegate_out[]	= "OK as Delegate";
 static const char flags_pwchange_out[]	= "Password Change required";
 static const char flags_service_out[]	= "Service Disabled";
 static const char flags_pwsvc_out[]	= "Password Changing Service";
 static const char flags_md5_out[]	= "RSA-MD5 supported";
+static const char flags_ok_to_auth_as_delegate_out[] = "Protocol transition with delegation allowed";
+static const char flags_no_auth_data_required_out[] = "No authorization data required";
 static const char flags_default_neg[]	= "-";
 static const char flags_default_sep[]	= " ";
 
@@ -115,7 +119,9 @@ static const struct flags_lookup_entry flags_table[] = {
 { KRB5_KDB_REQUIRES_PWCHANGE,	1,	flags_pwchange_in, flags_pwchange_out},
 { KRB5_KDB_DISALLOW_SVR,	0,	flags_service_in,  flags_service_out },
 { KRB5_KDB_PWCHANGE_SERVICE,	1,	flags_pwsvc_in,	   flags_pwsvc_out   },
-{ KRB5_KDB_SUPPORT_DESMD5,	1,	flags_md5_in,	   flags_md5_out     }
+{ KRB5_KDB_SUPPORT_DESMD5,	1,	flags_md5_in,	   flags_md5_out     },
+{ KRB5_KDB_OK_TO_AUTH_AS_DELEGATE,  1,	flags_ok_to_auth_as_delegate_in, flags_ok_to_auth_as_delegate_out },
+{ KRB5_KDB_NO_AUTH_DATA_REQUIRED,   1,	flags_no_auth_data_required_in,	flags_no_auth_data_required_out }
 };
 static const int flags_table_nents = sizeof(flags_table)/
 				     sizeof(flags_table[0]);
diff --git a/src/lib/krb5/asn.1/asn1_k_decode.c b/src/lib/krb5/asn.1/asn1_k_decode.c
index 1917d8974..b1b09371b 100644
--- a/src/lib/krb5/asn.1/asn1_k_decode.c
+++ b/src/lib/krb5/asn.1/asn1_k_decode.c
@@ -1616,6 +1616,47 @@ error_out:
     return retval;
 }
 
+asn1_error_code asn1_decode_s4u_userid(asn1buf *buf, krb5_s4u_userid *val)
+{
+    setup();
+    val->nonce = 0;
+    val->user = NULL;
+    val->subject_cert.data = NULL;
+    val->options = 0;
+    { begin_structure();
+        get_field(val->nonce,0,asn1_decode_int32);
+        alloc_principal(val->user);
+        opt_field(val->user,1,asn1_decode_principal_name,0);
+        get_field(val->user,2,asn1_decode_realm);
+        opt_lenfield(val->subject_cert.length,val->subject_cert.data,3,asn1_decode_charstring);
+        opt_field(val->options,4,asn1_decode_krb5_flags,0);
+        end_structure();
+    }
+    return 0;
+error_out:
+    krb5_free_principal(NULL, val->user);
+    krb5_free_data_contents(NULL, &val->subject_cert);
+    val->user = NULL;
+    val->subject_cert.data = NULL;
+    return retval;
+}
+
+asn1_error_code asn1_decode_pa_s4u_x509_user(asn1buf *buf, krb5_pa_s4u_x509_user *val)
+{
+    setup();
+    val->cksum.contents = NULL;
+    { begin_structure();
+        get_field(val->user_id,0,asn1_decode_s4u_userid);
+        get_field(val->cksum,1,asn1_decode_checksum);
+        end_structure();
+    }
+    return 0;
+error_out:
+    krb5_free_s4u_userid_contents(NULL, &val->user_id);
+    krb5_free_checksum_contents(NULL, &val->cksum);
+    return retval;
+}
+
 asn1_error_code asn1_decode_pa_pac_req(asn1buf *buf, krb5_pa_pac_req *val)
 {
     setup();
diff --git a/src/lib/krb5/asn.1/asn1_k_decode.h b/src/lib/krb5/asn.1/asn1_k_decode.h
index 7444443ba..fc62c8f4e 100644
--- a/src/lib/krb5/asn.1/asn1_k_decode.h
+++ b/src/lib/krb5/asn.1/asn1_k_decode.h
@@ -263,6 +263,10 @@ asn1_error_code asn1_decode_setpw_req
         (asn1buf *buf, krb5_data *rep, krb5_principal *principal);
 asn1_error_code asn1_decode_pa_for_user
         (asn1buf *buf, krb5_pa_for_user *val);
+asn1_error_code asn1_decode_s4u_userid
+        (asn1buf *buf, krb5_s4u_userid *val);
+asn1_error_code asn1_decode_pa_s4u_x509_user
+        (asn1buf *buf, krb5_pa_s4u_x509_user *val);
 asn1_error_code asn1_decode_pa_pac_req
         (asn1buf *buf, krb5_pa_pac_req *val);
 
diff --git a/src/lib/krb5/asn.1/asn1_k_encode.c b/src/lib/krb5/asn.1/asn1_k_encode.c
index ed01b7560..cd63ffbb9 100644
--- a/src/lib/krb5/asn.1/asn1_k_encode.c
+++ b/src/lib/krb5/asn.1/asn1_k_encode.c
@@ -263,6 +263,8 @@ static unsigned int optional_enc_kdc_rep_part(const void *p)
         optional |= (1u << 8);
     if (val->caddrs != NULL && val->caddrs[0] != NULL)
         optional |= (1u << 11);
+    if (val->enc_padata != NULL)
+        optional |= (1u << 12);
 
     return optional;
 }
@@ -1147,6 +1149,36 @@ static const struct field_info pa_for_user_fields[] = {
 
 DEFSEQTYPE(pa_for_user, krb5_pa_for_user, pa_for_user_fields, 0);
 
+/* [MS-SFU] Section 2.2.2. */
+static const struct field_info s4u_userid_fields[] = {
+    FIELDOF_NORM(krb5_s4u_userid, int32, nonce, 0),
+    FIELDOF_OPT(krb5_s4u_userid, principal, user, 1, 1),
+    FIELDOF_NORM(krb5_s4u_userid, realm_of_principal, user, 2),
+    FIELDOF_OPT(krb5_s4u_userid, ostring_data, subject_cert, 3, 3),
+    FIELDOF_OPT(krb5_s4u_userid, krb5_flags, options, 4, 4),
+};
+
+static unsigned int s4u_userid_optional (const void *p) {
+    const krb5_s4u_userid *val = p;
+    unsigned int optional = 0;
+    if (val->user != NULL && val->user->length != 0)
+        optional |= (1u)<<1;
+    if (val->subject_cert.length != 0)
+        optional |= (1u)<<3;
+    if (val->options != 0)
+        optional |= (1u)<<4;
+    return optional;
+}
+
+DEFSEQTYPE(s4u_userid, krb5_s4u_userid, s4u_userid_fields, s4u_userid_optional);
+
+static const struct field_info pa_s4u_x509_user_fields[] = {
+    FIELDOF_NORM(krb5_pa_s4u_x509_user, s4u_userid, user_id, 0),
+    FIELDOF_NORM(krb5_pa_s4u_x509_user, checksum, cksum, 1),
+};
+
+DEFSEQTYPE(pa_s4u_x509_user, krb5_pa_s4u_x509_user, pa_s4u_x509_user_fields, 0);
+
 /* draft-ietf-krb-wg-kerberos-referrals Appendix A. */
 static const struct field_info pa_svr_referral_data_fields[] = {
     FIELDOF_NORM(krb5_pa_svr_referral_data, realm_of_principal, principal, 0),
@@ -1323,6 +1355,8 @@ MAKE_FULL_ENCODER(encode_krb5_predicted_sam_response,
                   predicted_sam_response);
 MAKE_FULL_ENCODER(encode_krb5_setpw_req, setpw_req);
 MAKE_FULL_ENCODER(encode_krb5_pa_for_user, pa_for_user);
+MAKE_FULL_ENCODER(encode_krb5_s4u_userid, s4u_userid);
+MAKE_FULL_ENCODER(encode_krb5_pa_s4u_x509_user, pa_s4u_x509_user);
 MAKE_FULL_ENCODER(encode_krb5_pa_svr_referral_data, pa_svr_referral_data);
 MAKE_FULL_ENCODER(encode_krb5_pa_server_referral_data, pa_server_referral_data);
 MAKE_FULL_ENCODER(encode_krb5_etype_list, etype_list);
diff --git a/src/lib/krb5/asn.1/krb5_decode.c b/src/lib/krb5/asn.1/krb5_decode.c
index 7a08ec888..a2e9c0a4d 100644
--- a/src/lib/krb5/asn.1/krb5_decode.c
+++ b/src/lib/krb5/asn.1/krb5_decode.c
@@ -1061,6 +1061,18 @@ decode_krb5_pa_for_user(const krb5_data *code, krb5_pa_for_user **repptr)
 }
 
 krb5_error_code
+decode_krb5_pa_s4u_x509_user(const krb5_data *code, krb5_pa_s4u_x509_user **repptr)
+{
+    setup_buf_only(krb5_pa_s4u_x509_user *);
+    alloc_field(rep);
+
+    retval = asn1_decode_pa_s4u_x509_user(&buf, rep);
+    if (retval) clean_return(retval);
+
+    cleanup(free);
+}
+
+krb5_error_code
 decode_krb5_pa_pac_req(const krb5_data *code, krb5_pa_pac_req **repptr)
 {
     setup_buf_only(krb5_pa_pac_req *);
diff --git a/src/lib/krb5/krb/Makefile.in b/src/lib/krb5/krb/Makefile.in
index 9715e6dfc..8b8f6d2db 100644
--- a/src/lib/krb5/krb/Makefile.in
+++ b/src/lib/krb5/krb/Makefile.in
@@ -79,6 +79,7 @@ STLIBOBJS= \
 	rd_req_dec.o	\
 	rd_safe.o	\
 	recvauth.o	\
+	s4u_creds.o	\
 	sendauth.o	\
 	send_tgs.o	\
 	ser_actx.o	\
@@ -167,6 +168,7 @@ OBJS=	$(OUTPRE)addr_comp.$(OBJEXT)	\
 	$(OUTPRE)rd_req_dec.$(OBJEXT)	\
 	$(OUTPRE)rd_safe.$(OBJEXT)	\
 	$(OUTPRE)recvauth.$(OBJEXT)	\
+	$(OUTPRE)s4u_creds.$(OBJEXT)	\
 	$(OUTPRE)sendauth.$(OBJEXT)	\
 	$(OUTPRE)send_tgs.$(OBJEXT)	\
 	$(OUTPRE)ser_actx.$(OBJEXT)	\
@@ -256,6 +258,7 @@ SRCS=	$(srcdir)/addr_comp.c	\
 	$(srcdir)/rd_req_dec.c	\
 	$(srcdir)/rd_safe.c	\
 	$(srcdir)/recvauth.c	\
+	$(srcdir)/s4u_creds.c	\
 	$(srcdir)/sendauth.c	\
 	$(srcdir)/send_tgs.c	\
 	$(srcdir)/ser_actx.c	\
diff --git a/src/lib/krb5/krb/gc_frm_kdc.c b/src/lib/krb5/krb/gc_frm_kdc.c
index 3098e8e13..b3144c84e 100644
--- a/src/lib/krb5/krb/gc_frm_kdc.c
+++ b/src/lib/krb5/krb/gc_frm_kdc.c
@@ -1007,6 +1007,11 @@ krb5_get_cred_from_kdc_opt(krb5_context context, krb5_ccache ccache,
 
     DUMP_PRINC("gc_from_kdc: server as requested", supplied_server);
 
+    if (in_cred->second_ticket.length != 0 &&
+	(kdcopt & KDC_OPT_CNAME_IN_ADDL_TKT) == 0) {
+	kdcopt |= KDC_OPT_ENC_TKT_IN_SKEY;
+    }
+
     /*
      * Try requesting a service ticket from our local KDC with referrals
      * turned on.  If the first referral succeeds, follow a referral-only
@@ -1028,9 +1033,7 @@ krb5_get_cred_from_kdc_opt(krb5_context context, krb5_ccache ccache,
         retval = krb5_get_cred_via_tkt(context, tgtptr,
 				       KDC_OPT_CANONICALIZE | 
 				       FLAGS2OPTS(tgtptr->ticket_flags) |  
-				       kdcopt |
-				       (in_cred->second_ticket.length ?
-					KDC_OPT_ENC_TKT_IN_SKEY : 0),
+				       kdcopt,
 				       tgtptr->addresses, in_cred, out_cred);
 	if (retval) {
 	    DPRINTF(("gc_from_kdc: referral TGS-REQ request failed: <%s>\n",
@@ -1048,9 +1051,7 @@ krb5_get_cred_from_kdc_opt(krb5_context context, krb5_ccache ccache,
 		     "retrying without option.\n", referral_count + 1));
 	    retval = krb5_get_cred_via_tkt(context, tgtptr,
 					   FLAGS2OPTS(tgtptr->ticket_flags) |  
-					   kdcopt |
-					   (in_cred->second_ticket.length ?
-					    KDC_OPT_ENC_TKT_IN_SKEY : 0),
+					   kdcopt,
 					   tgtptr->addresses,
 					   in_cred, out_cred);
 	    /* Whether or not that succeeded, we're done. */
@@ -1090,9 +1091,7 @@ krb5_get_cred_from_kdc_opt(krb5_context context, krb5_ccache ccache,
 	    retval = krb5_get_cred_via_tkt(context, tgtptr,
 					   KDC_OPT_CANONICALIZE | 
 					   FLAGS2OPTS(tgtptr->ticket_flags) |  
-					   kdcopt |
-					   (in_cred->second_ticket.length ?
-					    KDC_OPT_ENC_TKT_IN_SKEY : 0),
+					   kdcopt,
 					   tgtptr->addresses,
 					   in_cred, out_cred);
 	    goto cleanup;
@@ -1257,9 +1256,7 @@ krb5_get_cred_from_kdc_opt(krb5_context context, krb5_ccache ccache,
     context->use_conf_ktypes = old_use_conf_ktypes;
     retval = krb5_get_cred_via_tkt(context, tgtptr,
 				   FLAGS2OPTS(tgtptr->ticket_flags) |
-				   kdcopt |
-				   (in_cred->second_ticket.length ?
-				    KDC_OPT_ENC_TKT_IN_SKEY : 0),
+				   kdcopt,
 				   tgtptr->addresses, in_cred, out_cred);
 
 cleanup:
diff --git a/src/lib/krb5/krb/gc_via_tkt.c b/src/lib/krb5/krb/gc_via_tkt.c
index 83c8026fc..273655ab5 100644
--- a/src/lib/krb5/krb/gc_via_tkt.c
+++ b/src/lib/krb5/krb/gc_via_tkt.c
@@ -1,7 +1,7 @@
 /*
  * lib/krb5/krb/gc_via_tgt.c
  *
- * Copyright 1990,1991,2007,2008 by the Massachusetts Institute of Technology.
+ * Copyright 1990,1991,2007-2009 by the Massachusetts Institute of Technology.
  * All Rights Reserved.
  *
  * Export of this software from the United States of America may
@@ -159,12 +159,34 @@ krb5_get_cred_via_tkt (krb5_context context, krb5_creds *tkt,
 		       krb5_flags kdcoptions, krb5_address *const *address,
 		       krb5_creds *in_cred, krb5_creds **out_cred)
 {
+    return krb5_get_cred_via_tkt_ext (context, tkt,
+				      kdcoptions, address,
+				      NULL, in_cred, NULL, NULL,
+				      NULL, NULL, out_cred, NULL);
+}
+
+krb5_error_code
+krb5_get_cred_via_tkt_ext (krb5_context context, krb5_creds *tkt,
+			   krb5_flags kdcoptions, krb5_address *const *address,
+			   krb5_pa_data **in_padata,
+			   krb5_creds *in_cred,
+			   krb5_error_code (*pacb_fct)(krb5_context,
+						       krb5_keyblock *,
+						       krb5_kdc_req *,
+						       void *),
+			   void *pacb_data,
+			   krb5_pa_data ***out_padata,
+			   krb5_pa_data ***out_enc_padata,
+			   krb5_creds **out_cred,
+			   krb5_keyblock **out_subkey)
+{
     krb5_error_code retval;
     krb5_kdc_rep *dec_rep;
     krb5_error *err_reply;
     krb5_response tgsrep;
     krb5_enctype *enctypes = 0;
     krb5_keyblock *subkey = NULL;
+    krb5_boolean s4u2self = FALSE, second_tkt;
 
 #ifdef DEBUG_REFERRALS
     printf("krb5_get_cred_via_tkt starting; referral flag is %s\n", kdcoptions&KDC_OPT_CANONICALIZE?"on":"off");
@@ -179,10 +201,13 @@ krb5_get_cred_via_tkt (krb5_context context, krb5_creds *tkt,
     if (!tkt->ticket.length)
 	return KRB5_NO_TKT_SUPPLIED;
 
-    if ((kdcoptions & KDC_OPT_ENC_TKT_IN_SKEY) && 
-	(!in_cred->second_ticket.length))
+    second_tkt = ((kdcoptions & (KDC_OPT_ENC_TKT_IN_SKEY | KDC_OPT_CNAME_IN_ADDL_TKT)) != 0);
+
+    if (second_tkt && !in_cred->second_ticket.length)
         return(KRB5_NO_2ND_TKT);
 
+    s4u2self = krb5int_find_pa_data(context, in_padata, KRB5_PADATA_S4U_X509_USER) ||
+	       krb5int_find_pa_data(context, in_padata, KRB5_PADATA_FOR_USER);
 
     /* check if we have the right TGT                    */
     /* tkt->server must be equal to                      */
@@ -210,13 +235,12 @@ krb5_get_cred_via_tkt (krb5_context context, krb5_creds *tkt,
 	enctypes[0] = in_cred->keyblock.enctype;
 	enctypes[1] = 0;
     }
-    
+
     retval = krb5int_send_tgs(context, kdcoptions, &in_cred->times, enctypes, 
 			   in_cred->server, address, in_cred->authdata,
-			   0,		/* no padata */
-			   (kdcoptions & KDC_OPT_ENC_TKT_IN_SKEY) ? 
-			   &in_cred->second_ticket : NULL,
-			   tkt, &tgsrep, &subkey);
+			   in_padata,
+			   second_tkt ? &in_cred->second_ticket : NULL,
+			   tkt, pacb_fct, pacb_data, &tgsrep, &subkey);
     if (enctypes)
 	free(enctypes);
     if (retval) {
@@ -318,8 +342,17 @@ krb5_get_cred_via_tkt (krb5_context context, krb5_creds *tkt,
     /* make sure the response hasn't been tampered with..... */
     retval = 0;
 
-    if (!krb5_principal_compare(context, dec_rep->client, tkt->client))
-	retval = KRB5_KDCREP_MODIFIED;
+    if (s4u2self && !IS_TGS_PRINC(context, dec_rep->ticket->server)) {
+	/* Final hop, check whether KDC supports S4U2Self */
+	if (krb5_principal_compare(context, dec_rep->client, in_cred->server))
+	    retval = KRB5KDC_ERR_PADATA_TYPE_NOSUPP;
+    } else if ((kdcoptions & KDC_OPT_CNAME_IN_ADDL_TKT) == 0) {
+	/* XXX for constrained delegation this check must be performed by caller
+	 * as we don't have access to the key to decrypt the evidence ticket.
+	 */
+	if (!krb5_principal_compare(context, dec_rep->client, tkt->client))
+	    retval = KRB5_KDCREP_MODIFIED;
+    }
 
     if (retval == 0)
 	retval = check_reply_server(context, kdcoptions, in_cred, dec_rep);
@@ -356,13 +389,26 @@ krb5_get_cred_via_tkt (krb5_context context, krb5_creds *tkt,
 	retval = KRB5_KDCREP_SKEW;
 	goto error_3;
     }
+
+    if (out_padata != NULL) {
+	*out_padata = dec_rep->padata;
+	dec_rep->padata = NULL;
+    }
+    if (out_enc_padata != NULL) {
+	*out_enc_padata = dec_rep->enc_part2->enc_padata;
+	dec_rep->enc_part2->enc_padata = NULL;
+    }
     
     retval = krb5_kdcrep2creds(context, dec_rep, address, 
 			       &in_cred->second_ticket,  out_cred);
 
 error_3:;
-    if (subkey != NULL)
-      krb5_free_keyblock(context, subkey);
+    if (subkey != NULL) {
+      if (retval == 0 && out_subkey != NULL)
+	  *out_subkey = subkey;
+      else
+	  krb5_free_keyblock(context, subkey);
+    }
     
     memset(dec_rep->enc_part2->session->contents, 0,
 	   dec_rep->enc_part2->session->length);
diff --git a/src/lib/krb5/krb/get_creds.c b/src/lib/krb5/krb/get_creds.c
index c02ddedc6..dad3e1a91 100644
--- a/src/lib/krb5/krb/get_creds.c
+++ b/src/lib/krb5/krb/get_creds.c
@@ -46,7 +46,7 @@
 #include "k5-int.h"
 #include "int-proto.h"
 
-static krb5_error_code
+krb5_error_code
 krb5_get_credentials_core(krb5_context context, krb5_flags options,
 			  krb5_creds *in_creds, krb5_creds *mcreds,
 			  krb5_flags *fields)
@@ -87,11 +87,14 @@ krb5_get_credentials_core(krb5_context context, krb5_flags options,
 	if (ret)
 	    return ret;
     }
-    if (options & KRB5_GC_USER_USER) {
+    if (options & (KRB5_GC_USER_USER | KRB5_GC_CONSTRAINED_DELEGATION)) {
 	/* also match on identical 2nd tkt and tkt encrypted in a
 	   session key */
-	*fields |= KRB5_TC_MATCH_2ND_TKT|KRB5_TC_MATCH_IS_SKEY;
-	mcreds->is_skey = TRUE;
+	*fields |= KRB5_TC_MATCH_2ND_TKT;
+	if (options & KRB5_GC_USER_USER) {
+	    *fields |= KRB5_TC_MATCH_IS_SKEY;
+	    mcreds->is_skey = TRUE;
+	}
 	mcreds->second_ticket = in_creds->second_ticket;
 	if (!in_creds->second_ticket.length)
 	    return KRB5_NO_2ND_TKT;
@@ -113,25 +116,35 @@ krb5_get_credentials(krb5_context context, krb5_flags options,
     int not_ktype;
     int kdcopt = 0;
 
-    retval = krb5_get_credentials_core(context, options,
-				       in_creds,
-				       &mcreds, &fields);
+    if ((options & KRB5_GC_CONSTRAINED_DELEGATION) == 0) {
+	retval = krb5_get_credentials_core(context, options,
+					   in_creds,
+					   &mcreds, &fields);
 
-    if (retval) return retval;
+	if (retval)
+	    return retval;
 
-    if ((ncreds = (krb5_creds *)malloc(sizeof(krb5_creds))) == NULL)
-	return ENOMEM;
+	if ((ncreds = (krb5_creds *)malloc(sizeof(krb5_creds))) == NULL)
+	    return ENOMEM;
 
-    memset(ncreds, 0, sizeof(krb5_creds));
-    ncreds->magic = KV5M_CREDS;
+	memset(ncreds, 0, sizeof(krb5_creds));
+	ncreds->magic = KV5M_CREDS;
 
-    /* The caller is now responsible for cleaning up in_creds */
-    if ((retval = krb5_cc_retrieve_cred(context, ccache, fields, &mcreds,
-					ncreds))) {
-	free(ncreds);
-	ncreds = in_creds;
+	/* The caller is now responsible for cleaning up in_creds */
+	if ((retval = krb5_cc_retrieve_cred(context, ccache, fields, &mcreds,
+					    ncreds))) {
+	    free(ncreds);
+	    ncreds = in_creds;
+	} else {
+	    *out_creds = ncreds;
+	}
     } else {
-	*out_creds = ncreds;
+	/*
+	 * To do this usefully for constrained delegation, we would
+	 * need to look inside second_ticket, which we can't do.
+	 */
+	ncreds = in_creds;
+	retval = KRB5_CC_NOTFOUND;
     }
 
     if ((retval != KRB5_CC_NOTFOUND && retval != KRB5_CC_NOT_KTYPE)
@@ -145,6 +158,15 @@ krb5_get_credentials(krb5_context context, krb5_flags options,
 
     if (options & KRB5_GC_CANONICALIZE)
 	kdcopt |= KDC_OPT_CANONICALIZE;
+    if (options & KRB5_GC_FORWARDABLE)
+	kdcopt |= KDC_OPT_FORWARDABLE;
+    if (options & KRB5_GC_NO_TRANSIT_CHECK)
+	kdcopt |= KDC_OPT_DISABLE_TRANSITED_CHECK;
+    if (options & KRB5_GC_CONSTRAINED_DELEGATION) {
+	if (options & KRB5_GC_USER_USER)
+	    return EINVAL;
+	kdcopt |= KDC_OPT_FORWARDABLE | KDC_OPT_CNAME_IN_ADDL_TKT;
+    }
 
     retval = krb5_get_cred_from_kdc_opt(context, ccache, ncreds,
 					out_creds, &tgts, kdcopt);
@@ -160,6 +182,13 @@ krb5_get_credentials(krb5_context context, krb5_flags options,
 	}
 	krb5_free_tgt_creds(context, tgts);
     }
+    if (!retval && (options & KRB5_GC_CONSTRAINED_DELEGATION)) {
+	if (((*out_creds)->ticket_flags & TKT_FLG_FORWARDABLE) == 0) {
+	    retval = KRB5_TKT_NOT_FORWARDABLE;
+	    krb5_free_creds(context, *out_creds);
+	    *out_creds = NULL;
+	}
+    }
     /*
      * Translate KRB5_CC_NOTFOUND if we previously got
      * KRB5_CC_NOT_KTYPE from krb5_cc_retrieve_cred(), in order to
@@ -175,7 +204,7 @@ krb5_get_credentials(krb5_context context, krb5_flags options,
 	&& not_ktype)
 	retval = KRB5_CC_NOT_KTYPE;
 
-    if (!retval) {
+    if (!retval && (options & KRB5_GC_NO_STORE) == 0) {
         /* the purpose of the krb5_get_credentials call is to 
          * obtain a set of credentials for the caller.  the 
          * krb5_cc_store_cred() call is to optimize performance
@@ -184,6 +213,7 @@ krb5_get_credentials(krb5_context context, krb5_flags options,
          */
 	krb5_cc_store_cred(context, ccache, *out_creds);
     }
+
     return retval;
 }
 
@@ -337,3 +367,4 @@ krb5_get_renewed_creds(krb5_context context, krb5_creds *creds, krb5_principal c
     return(krb5_validate_or_renew_creds(context, creds, client, ccache,
 					in_tkt_service, 0));
 }
+
diff --git a/src/lib/krb5/krb/get_in_tkt.c b/src/lib/krb5/krb/get_in_tkt.c
index 018676dbe..63594ddfd 100644
--- a/src/lib/krb5/krb/get_in_tkt.c
+++ b/src/lib/krb5/krb/get_in_tkt.c
@@ -493,6 +493,55 @@ static const krb5_enctype get_in_tkt_enctypes[] = {
     0
 };
 
+static krb5_error_code
+rewrite_server_realm(krb5_context context,
+		     krb5_const_principal old_server,
+		     const krb5_data *realm,
+		     krb5_boolean tgs,
+		     krb5_principal *server)
+{
+    krb5_error_code retval;
+
+    assert(*server == NULL);
+
+    retval = krb5_copy_principal(context, old_server, server);
+    if (retval)
+	return retval;
+
+    krb5_free_data_contents(context, &(*server)->realm);
+    (*server)->realm.data = NULL;
+
+    retval = krb5int_copy_data_contents(context, realm, &(*server)->realm);
+    if (retval)
+	goto cleanup;
+
+    if (tgs) {
+	krb5_free_data_contents(context, &(*server)->data[1]);
+	(*server)->data[1].data = NULL;
+
+	retval = krb5int_copy_data_contents(context, realm, &(*server)->data[1]);
+	if (retval)
+	    goto cleanup;
+    }
+
+cleanup:
+    if (retval) {
+	krb5_free_principal(context, *server);
+	*server = NULL;
+    }
+
+    return retval;
+}
+
+static inline int
+tgt_is_local_realm(krb5_creds *tgt)
+{
+    return (tgt->server->length == 2
+            && data_eq_string(tgt->server->data[0], KRB5_TGS_NAME)
+            && data_eq(tgt->server->data[1], tgt->client->realm)
+            && data_eq(tgt->server->realm, tgt->client->realm));
+}
+
 krb5_error_code KRB5_CALLCONV
 krb5_get_in_tkt(krb5_context context,
 		krb5_flags options,
@@ -521,6 +570,8 @@ krb5_get_in_tkt(krb5_context context,
     int             use_master = 0;
     int			referral_count = 0;
     krb5_principal_data	referred_client;
+    krb5_principal	referred_server = NULL;
+    krb5_boolean	is_tgt_req;
 
 #if APPLE_PKINIT
     inTktDebug("krb5_get_in_tkt top\n");
@@ -616,6 +667,8 @@ krb5_get_in_tkt(krb5_context context,
 	    goto cleanup;
     }
 	    
+    is_tgt_req = tgt_is_local_realm(creds);
+
     while (1) {
 	if (loopcount++ > MAX_IN_TKT_LOOPS) {
 	    retval = KRB5_GET_IN_TKT_LOOP;
@@ -687,6 +740,21 @@ krb5_get_in_tkt(krb5_context context,
 		if (retval)
 		    goto cleanup;
 		request.client = &referred_client;
+
+		if (referred_server != NULL) {
+		    krb5_free_principal(context, referred_server);
+		    referred_server = NULL;
+		}
+
+		retval = rewrite_server_realm(context,
+					      creds->server,
+					      &referred_client.realm,
+					      is_tgt_req,
+					      &referred_server);
+		if (retval)
+		    goto cleanup;
+		request.server = referred_server;
+
 		continue;
 	    } else {
 		retval = (krb5_error_code) err_reply->error 
@@ -739,6 +807,8 @@ cleanup:
     }
     if (referred_client.realm.data)
 	krb5_free_data_contents(context, &referred_client.realm);
+    if (referred_server)
+	krb5_free_principal(context, referred_server);
     return (retval);
 }
 
@@ -939,6 +1009,52 @@ sort_krb5_padata_sequence(krb5_context context, krb5_data *realm,
     return 0;
 }
 
+static krb5_error_code
+build_in_tkt_name(krb5_context context,
+		  char *in_tkt_service,
+		  krb5_const_principal client,
+		  krb5_principal *server)
+{
+    krb5_error_code ret;
+
+    *server = NULL;
+
+    if (in_tkt_service) {
+	/* this is ugly, because so are the data structures involved.  I'm
+	   in the library, so I'm going to manipulate the data structures
+	   directly, otherwise, it will be worse. */
+
+        if ((ret = krb5_parse_name(context, in_tkt_service, server)))
+	    return ret;
+
+	/* stuff the client realm into the server principal.
+	   realloc if necessary */
+	if ((*server)->realm.length < client->realm.length) {
+	    char *p = realloc((*server)->realm.data,
+			      client->realm.length);
+	    if (p == NULL) {
+		krb5_free_principal(context, *server);
+		*server = NULL;
+		return ENOMEM;
+	    }
+	    (*server)->realm.data = p;
+	}
+
+	(*server)->realm.length = client->realm.length;
+	memcpy((*server)->realm.data, client->realm.data, client->realm.length);
+    } else {
+	ret = krb5_build_principal_ext(context, server,
+				       client->realm.length,
+				       client->realm.data,
+				       KRB5_TGS_NAME_SIZE,
+				       KRB5_TGS_NAME,
+				       client->realm.length,
+				       client->realm.data,
+				       0);
+    }
+    return ret;
+}
+
 krb5_error_code KRB5_CALLCONV
 krb5_get_init_creds(krb5_context context,
 		    krb5_creds *creds,
@@ -1125,41 +1241,9 @@ krb5_get_init_creds(krb5_context context,
 	client->type == KRB5_NT_ENTERPRISE_PRINCIPAL;
 
     /* service */
-    
-    if (in_tkt_service) {
-	/* this is ugly, because so are the data structures involved.  I'm
-	   in the library, so I'm going to manipulate the data structures
-	   directly, otherwise, it will be worse. */
-
-        if ((ret = krb5_parse_name(context, in_tkt_service, &request.server)))
-	    goto cleanup;
-
-	/* stuff the client realm into the server principal.
-	   realloc if necessary */
-	if (request.server->realm.length < request.client->realm.length) {
-	    char *p = realloc(request.server->realm.data,
-			      request.client->realm.length);
-	    if (p == NULL) {
-		ret = ENOMEM;
-		goto cleanup;
-	    }
-	    request.server->realm.data = p;
-	}
-
-	request.server->realm.length = request.client->realm.length;
-	memcpy(request.server->realm.data, request.client->realm.data,
-	       request.client->realm.length);
-    } else {
-	if ((ret = krb5_build_principal_ext(context, &request.server,
-					   request.client->realm.length,
-					   request.client->realm.data,
-					   KRB5_TGS_NAME_SIZE,
-					   KRB5_TGS_NAME,
-					   request.client->realm.length,
-					   request.client->realm.data,
-					   0)))
-	    goto cleanup;
-    }
+    if ((ret = build_in_tkt_name(context, in_tkt_service,
+				 request.client, &request.server)))
+	goto cleanup;
 
     krb5_preauth_request_context_init(context);
 
@@ -1337,8 +1421,10 @@ krb5_get_init_creds(krb5_context context,
 		}
 		preauth_to_use = out_padata;
 		out_padata = NULL;
-		krb5_free_error(context, err_reply);
-		err_reply = NULL;
+		if (err_reply->error == KDC_ERR_PREAUTH_REQUIRED) {
+		    krb5_free_error(context, err_reply);
+		    err_reply = NULL;
+		}
 		ret = sort_krb5_padata_sequence(context,
 						&request.server->realm,
 						preauth_to_use);
@@ -1365,6 +1451,14 @@ krb5_get_init_creds(krb5_context context,
 		if (ret)
 		    goto cleanup;
 		request.client = &referred_client;
+
+		krb5_free_principal(context, request.server);
+		request.server = NULL;
+
+		ret = build_in_tkt_name(context, in_tkt_service,
+					request.client, &request.server);
+		if (ret)
+		    goto cleanup;
 	    } else {
 		if (retry)  {
 		    /* continue to next iteration */
diff --git a/src/lib/krb5/krb/int-proto.h b/src/lib/krb5/krb/int-proto.h
index b81fe2566..cc0c9f2de 100644
--- a/src/lib/krb5/krb/int-proto.h
+++ b/src/lib/krb5/krb/int-proto.h
@@ -59,11 +59,31 @@ krb5_get_cred_from_kdc_opt(krb5_context context, krb5_ccache ccache,
 			   krb5_creds *in_cred, krb5_creds **out_cred,
 			   krb5_creds ***tgts, int kdcopt);
 
+krb5_error_code
+krb5_get_credentials_core(krb5_context context, krb5_flags options,
+			  krb5_creds *in_creds, krb5_creds *mcreds,
+			  krb5_flags *fields);
+
 #define in_clock_skew(date, now) (labs((date)-(now)) < context->clockskew)
 
 #define IS_TGS_PRINC(c, p)						\
     (krb5_princ_size((c), (p)) == 2 &&					\
      data_eq_string(*krb5_princ_component((c), (p), 0), KRB5_TGS_NAME))
 
+krb5_error_code
+krb5_get_cred_via_tkt_ext (krb5_context context, krb5_creds *tkt,
+			   krb5_flags kdcoptions, krb5_address *const *address,
+			   krb5_pa_data **in_padata,
+			   krb5_creds *in_cred,
+			   krb5_error_code (*gcvt_fct)(krb5_context,
+						       krb5_keyblock *,
+						       krb5_kdc_req *,
+						       void *),
+			   void *gcvt_data,
+			   krb5_pa_data ***out_padata,
+			   krb5_pa_data ***enc_padata,
+			   krb5_creds **out_cred,
+			   krb5_keyblock **out_subkey);
+
 #endif /* KRB5_INT_FUNC_PROTO__ */
 
diff --git a/src/lib/krb5/krb/kfree.c b/src/lib/krb5/krb/kfree.c
index bec9a61bf..8cef95431 100644
--- a/src/lib/krb5/krb/kfree.c
+++ b/src/lib/krb5/krb/kfree.c
@@ -170,7 +170,7 @@ krb5_free_checksum_contents(krb5_context context, register krb5_checksum *val)
     if (val == NULL)
 	return;
     free(val->contents);
-    val->contents = 0;
+    val->contents = NULL;
 }
 
 void KRB5_CALLCONV
@@ -297,6 +297,7 @@ krb5_free_enc_kdc_rep_part(krb5_context context, register krb5_enc_kdc_rep_part
     krb5_free_last_req(context, val->last_req);
     krb5_free_principal(context, val->server);
     krb5_free_addresses(context, val->caddrs);
+    krb5_free_pa_data(context, val->enc_padata);
     free(val);
 }
 
@@ -755,6 +756,30 @@ krb5_free_pa_for_user(krb5_context context, krb5_pa_for_user *req)
 }
 
 void KRB5_CALLCONV
+krb5_free_s4u_userid_contents(krb5_context context, krb5_s4u_userid *user_id)
+{
+    if (user_id == NULL)
+	return;
+    user_id->nonce = 0;
+    krb5_free_principal(context, user_id->user);
+    user_id->user = NULL;
+    krb5_free_data_contents(context, &user_id->subject_cert);
+    user_id->subject_cert.length = 0;
+    user_id->subject_cert.data = NULL;
+    user_id->options = 0;
+}
+
+void KRB5_CALLCONV
+krb5_free_pa_s4u_x509_user(krb5_context context, krb5_pa_s4u_x509_user *req)
+{
+    if (req == NULL)
+	return;
+    krb5_free_s4u_userid_contents(context, &req->user_id);
+    krb5_free_checksum_contents(context, &req->cksum);
+    free(req);
+}
+
+void KRB5_CALLCONV
 krb5_free_pa_server_referral_data(krb5_context context,
 				  krb5_pa_server_referral_data *ref)
 {
diff --git a/src/lib/krb5/krb/preauth2.c b/src/lib/krb5/krb/preauth2.c
index e6f4215d5..996cbfd36 100644
--- a/src/lib/krb5/krb/preauth2.c
+++ b/src/lib/krb5/krb/preauth2.c
@@ -1706,6 +1706,59 @@ krb5_error_code pa_sam_2(krb5_context context,
    return(0);
 }
 
+static krb5_error_code pa_s4u_x509_user(
+    krb5_context context,
+    krb5_kdc_req *request,
+    krb5_pa_data *in_padata,
+    krb5_pa_data **out_padata,
+    krb5_data *salt,
+    krb5_data *s2kparams,
+    krb5_enctype *etype,
+    krb5_keyblock *as_key,
+    krb5_prompter_fct prompter,
+    void *prompter_data,
+    krb5_gic_get_as_key_fct gak_fct,
+    void *gak_data)
+{
+    krb5_s4u_userid *userid = (krb5_s4u_userid *)gak_data; /* XXX private contract */
+    krb5_pa_data *s4u_padata;
+    krb5_error_code code;
+    krb5_principal client;
+
+    *out_padata = NULL;
+
+    if (userid == NULL)
+	return EINVAL;
+
+    code = krb5_copy_principal(context, request->client, &client);
+    if (code != 0)
+	return code;
+
+    if (userid->user != NULL)
+	krb5_free_principal(context, userid->user);
+    userid->user = client;
+
+    if (userid->subject_cert.length != 0) {
+	s4u_padata = malloc(sizeof(*s4u_padata));
+	if (s4u_padata == NULL)
+	    return ENOMEM;
+
+	s4u_padata->magic = KV5M_PA_DATA;
+	s4u_padata->pa_type = KRB5_PADATA_S4U_X509_USER;
+	s4u_padata->contents = malloc(userid->subject_cert.length);
+	if (s4u_padata->contents == NULL) {
+	    free(s4u_padata);
+	    return ENOMEM;
+	}
+	memcpy(s4u_padata->contents, userid->subject_cert.data, userid->subject_cert.length);
+	s4u_padata->length = userid->subject_cert.length;
+
+	*out_padata = s4u_padata;
+    }
+
+    return 0;
+}
+
 /* FIXME - order significant? */
 static const pa_types_t pa_types[] = {
     {
@@ -1751,6 +1804,11 @@ static const pa_types_t pa_types[] = {
 	PA_INFO,
     },
     {
+	KRB5_PADATA_S4U_X509_USER,
+	pa_s4u_x509_user,
+	PA_INFO,
+    },
+    {
 	-1,
 	NULL,
 	0,
diff --git a/src/lib/krb5/krb/s4u_creds.c b/src/lib/krb5/krb/s4u_creds.c
new file mode 100644
index 000000000..613bbef1f
--- /dev/null
+++ b/src/lib/krb5/krb/s4u_creds.c
@@ -0,0 +1,829 @@
+/* -*- mode: c; indent-tabs-mode: nil -*- */
+/*
+ * lib/krb5/krb/s4u_creds.c
+ *
+ * Copyright (C) 2009 by the Massachusetts Institute of Technology.
+ * All rights reserved.
+ *
+ * Export of this software from the United States of America may
+ *   require a specific license from the United States Government.
+ *   It is the responsibility of any person or organization contemplating
+ *   export to obtain such a license before exporting.
+ *
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of M.I.T. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission.  Furthermore if you modify this software you must label
+ * your software as modified software and not distribute it in such a
+ * fashion that it might be confused with the original M.I.T. software.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is" without express
+ * or implied warranty.
+ *
+ *
+ *
+ */
+
+#include "k5-int.h"
+#include "int-proto.h"
+
+/* Convert ticket flags to necessary KDC options */
+#define FLAGS2OPTS(flags) (flags & KDC_TKT_COMMON_MASK)
+
+/*
+ * Implements S4U2Self, by which a service can request a ticket to
+ * itself on behalf of an arbitrary principal.
+ */
+
+static krb5_error_code
+krb5_get_as_key_noop(
+    krb5_context context,
+    krb5_principal client,
+    krb5_enctype etype,
+    krb5_prompter_fct prompter,
+    void *prompter_data,
+    krb5_data *salt,
+    krb5_data *params,
+    krb5_keyblock *as_key,
+    void *gak_data)
+{
+    /* force a hard error, we don't actually have the key */
+    return KDC_ERR_PREAUTH_FAILED;
+}
+
+static krb5_error_code
+s4u_identify_user(krb5_context context,
+                  krb5_creds *in_creds,
+                  krb5_data *subject_cert,
+                  krb5_principal *canon_user)
+{
+    krb5_error_code code;
+    krb5_preauthtype ptypes[1] = { KRB5_PADATA_S4U_X509_USER };
+    krb5_creds creds;
+    int use_master = 0;
+    krb5_get_init_creds_opt *opts = NULL;
+    krb5_gic_opt_ext *opte = NULL;
+    krb5_principal_data client_data;
+    krb5_principal client;
+    krb5_s4u_userid userid;
+
+    *canon_user = NULL;
+
+    if (in_creds->client == NULL && subject_cert == NULL) {
+        return EINVAL;
+    }
+
+    if (in_creds->client != NULL &&
+        krb5_princ_type(context, in_creds->client) !=
+            KRB5_NT_ENTERPRISE_PRINCIPAL)
+        /* we already know the realm of the user */
+        return krb5_copy_principal(context, in_creds->client, canon_user);
+
+    memset(&creds, 0, sizeof(creds));
+
+    memset(&userid, 0, sizeof(userid));
+    if (subject_cert != NULL)
+        userid.subject_cert = *subject_cert;
+
+    code = krb5_get_init_creds_opt_alloc(context, &opts);
+    if (code != 0)
+        goto cleanup;
+    krb5_get_init_creds_opt_set_tkt_life(opts, 15);
+    krb5_get_init_creds_opt_set_renew_life(opts, 0);
+    krb5_get_init_creds_opt_set_forwardable(opts, 0);
+    krb5_get_init_creds_opt_set_proxiable(opts, 0);
+    krb5_get_init_creds_opt_set_canonicalize(opts, 1);
+    krb5_get_init_creds_opt_set_preauth_list(opts, ptypes, 1);
+    code = krb5int_gic_opt_to_opte(context, opts, &opte,
+                                   0, "s4u_identify_user");
+    if (code != 0)
+        goto cleanup;
+
+    if (in_creds->client != NULL)
+        client = in_creds->client;
+    else {
+        client_data.magic = KV5M_PRINCIPAL;
+        client_data.realm = in_creds->server->realm;
+        /* should this be NULL, empty or a fixed string? XXX */
+        client_data.data = NULL;
+        client_data.length = 0;
+        client_data.type = KRB5_NT_ENTERPRISE_PRINCIPAL;
+        client = &client_data;
+    }
+
+    code = krb5_get_init_creds(context, &creds, in_creds->client,
+                               NULL, NULL, 0, NULL, opte,
+                               krb5_get_as_key_noop, &userid,
+                               &use_master, NULL);
+    if (code == 0 ||
+        code == KDC_ERR_PREAUTH_REQUIRED ||
+        code == KDC_ERR_PREAUTH_FAILED) {
+        *canon_user = userid.user;
+        userid.user = NULL;
+        code = 0;
+    }
+
+cleanup:
+    krb5_free_cred_contents(context, &creds);
+    if (opts != NULL)
+        krb5_get_init_creds_opt_free(context, opts);
+    if (userid.user != NULL)
+        krb5_free_principal(context, userid.user);
+
+    return code;
+}
+
+static krb5_error_code
+make_pa_for_user_checksum(krb5_context context,
+                          krb5_keyblock *key,
+                          krb5_pa_for_user *req,
+                          krb5_checksum *cksum)
+{
+    krb5_error_code code;
+    int i;
+    krb5_int32 name_type;
+    char *p;
+    krb5_data data;
+    krb5_cksumtype cksumtype;
+
+    data.length = 4;
+    for (i = 0; i < krb5_princ_size(context, req->user); i++) {
+        data.length += krb5_princ_component(context, req->user, i)->length;
+    }
+    data.length += krb5_princ_realm(context, req->user)->length;
+    data.length += req->auth_package.length;
+
+    p = data.data = malloc(data.length);
+    if (data.data == NULL)
+        return ENOMEM;
+
+    name_type = krb5_princ_type(context, req->user);
+    p[0] = (name_type >> 0 ) & 0xFF;
+    p[1] = (name_type >> 8 ) & 0xFF;
+    p[2] = (name_type >> 16) & 0xFF;
+    p[3] = (name_type >> 24) & 0xFF;
+    p += 4;
+
+    for (i = 0; i < krb5_princ_size(context, req->user); i++) {
+        memcpy(p, krb5_princ_component(context, req->user, i)->data,
+               krb5_princ_component(context, req->user, i)->length);
+        p += krb5_princ_component(context, req->user, i)->length;
+    }
+
+    memcpy(p, krb5_princ_realm(context, req->user)->data,
+           krb5_princ_realm(context, req->user)->length);
+    p += krb5_princ_realm(context, req->user)->length;
+
+    memcpy(p, req->auth_package.data, req->auth_package.length);
+
+    code = krb5int_c_mandatory_cksumtype(context, key->enctype, &cksumtype);
+    if (code != 0) {
+        free(data.data);
+        return code;
+    }
+
+    code = krb5_c_make_checksum(context, cksumtype, key,
+                                KRB5_KEYUSAGE_APP_DATA_CKSUM, &data,
+                                cksum);
+
+    free(data.data);
+
+    return code;
+}
+
+static krb5_error_code
+build_pa_for_user(krb5_context context,
+                  krb5_creds *tgt,
+                  krb5_s4u_userid *userid,
+                  krb5_pa_data **out_padata)
+{
+    krb5_error_code code;
+    krb5_pa_data *padata;
+    krb5_pa_for_user for_user;
+    krb5_data *for_user_data = NULL;
+    char package[] = "Kerberos";
+
+    if (userid->user == NULL) {
+        code = EINVAL;
+        goto cleanup;
+    }
+
+    memset(&for_user, 0, sizeof(for_user));
+    for_user.user = userid->user;
+    for_user.auth_package.data = package;
+    for_user.auth_package.length = sizeof(package) - 1;
+
+    code = make_pa_for_user_checksum(context, &tgt->keyblock,
+                                     &for_user, &for_user.cksum);
+    if (code != 0)
+        goto cleanup;
+
+    code = encode_krb5_pa_for_user(&for_user, &for_user_data);
+    if (code != 0)
+        goto cleanup;
+
+    padata = malloc(sizeof(*padata));
+    if (padata == NULL) {
+        code = ENOMEM;
+        goto cleanup;
+    }
+
+    padata->magic = KV5M_PA_DATA;
+    padata->pa_type = KRB5_PADATA_FOR_USER;
+    padata->length = for_user_data->length;
+    padata->contents = (krb5_octet *)for_user_data->data;
+
+    free(for_user_data);
+    for_user_data = NULL;
+
+    *out_padata = padata;
+
+cleanup:
+    if (for_user.cksum.contents != NULL)
+        krb5_free_checksum_contents(context, &for_user.cksum);
+    krb5_free_data(context, for_user_data);
+
+    return code;
+}
+
+/*
+ * This function is invoked by krb5int_send_tgs() just before
+ * the request is encoded; it gives us access to the nonce and
+ * subkey without requiring them to be generated by the caller.
+ */
+static krb5_error_code
+build_pa_s4u_x509_user(krb5_context context,
+                       krb5_keyblock *subkey,
+                       krb5_kdc_req *tgsreq,
+                       void *gcvt_data)
+{
+    krb5_error_code code;
+    krb5_pa_s4u_x509_user *s4u_user = (krb5_pa_s4u_x509_user *)gcvt_data;
+    krb5_data *data = NULL;
+    krb5_pa_data **padata;
+    krb5_cksumtype cksumtype;
+    int i;
+
+    assert(s4u_user->cksum.contents == NULL);
+
+    s4u_user->user_id.nonce = tgsreq->nonce;
+
+    code = encode_krb5_s4u_userid(&s4u_user->user_id, &data);
+    if (code != 0)
+        goto cleanup;
+
+    /* [MS-SFU] 2.2.2: unusual to say the least, but enc_padata secures it */
+    if (subkey->enctype == ENCTYPE_ARCFOUR_HMAC ||
+        subkey->enctype == ENCTYPE_ARCFOUR_HMAC_EXP) {
+        cksumtype = CKSUMTYPE_RSA_MD4;
+    } else {
+        code = krb5int_c_mandatory_cksumtype(context, subkey->enctype,
+                                             &cksumtype);
+    }
+    if (code != 0)
+        goto cleanup;
+
+    code = krb5_c_make_checksum(context, cksumtype, subkey,
+                                KRB5_KEYUSAGE_PA_S4U_X509_USER_REQUEST, data,
+                                &s4u_user->cksum);
+    if (code != 0)
+        goto cleanup;
+
+    krb5_free_data(context, data);
+    data = NULL;
+
+    code = encode_krb5_pa_s4u_x509_user(s4u_user, &data);
+    if (code != 0)
+        goto cleanup;
+
+    assert(tgsreq->padata != NULL);
+
+    for (i = 0; tgsreq->padata[i] != NULL; i++)
+        ;
+
+    padata = realloc(tgsreq->padata,
+                     (i + 2) * sizeof(krb5_pa_data *));
+    if (padata == NULL) {
+        code = ENOMEM;
+        goto cleanup;
+    }
+    tgsreq->padata = padata;
+
+    padata[i] = malloc(sizeof(krb5_pa_data));
+    if (padata[i] == NULL) {
+        code = ENOMEM;
+        goto cleanup;
+    }
+    padata[i]->magic = KV5M_PA_DATA;
+    padata[i]->pa_type = KRB5_PADATA_S4U_X509_USER;
+    padata[i]->length = data->length;
+    padata[i]->contents = (krb5_octet *)data->data;
+
+    padata[i + 1] = NULL;
+
+    free(data);
+    data = NULL;
+
+cleanup:
+    if (code != 0 && s4u_user->cksum.contents != NULL) {
+        krb5_free_checksum_contents(context, &s4u_user->cksum);
+        s4u_user->cksum.contents = NULL;
+    }
+    krb5_free_data(context, data);
+
+    return code;
+}
+
+static krb5_error_code
+verify_s4u2self_reply(krb5_context context,
+                      krb5_keyblock *subkey,
+                      krb5_pa_s4u_x509_user *req_s4u_user,
+                      krb5_pa_data **rep_padata,
+                      krb5_pa_data **enc_padata)
+{
+    krb5_error_code code;
+    krb5_pa_data *rep_s4u_padata, *enc_s4u_padata;
+    krb5_pa_s4u_x509_user *rep_s4u_user = NULL;
+    krb5_data data, *datap = NULL;
+    krb5_keyusage usage;
+    krb5_boolean valid;
+    krb5_boolean not_newer;
+
+    assert(req_s4u_user != NULL);
+
+    switch (subkey->enctype) {
+    case ENCTYPE_DES_CBC_CRC:
+    case ENCTYPE_DES_CBC_MD4:
+    case ENCTYPE_DES_CBC_MD5:
+    case ENCTYPE_DES3_CBC_SHA1:
+    case ENCTYPE_DES3_CBC_RAW:
+    case ENCTYPE_ARCFOUR_HMAC:
+    case ENCTYPE_ARCFOUR_HMAC_EXP :
+        not_newer = TRUE;
+        break;
+    default:
+        not_newer = FALSE;
+        break;
+    }
+
+    enc_s4u_padata = krb5int_find_pa_data(context,
+                                          enc_padata,
+                                          KRB5_PADATA_S4U_X509_USER);
+
+    /* XXX this will break newer enctypes with a MIT 1.7 KDC */
+    rep_s4u_padata = krb5int_find_pa_data(context,
+                                          rep_padata,
+                                          KRB5_PADATA_S4U_X509_USER);
+    if (rep_s4u_padata == NULL) {
+        if (not_newer == FALSE || enc_s4u_padata != NULL)
+            return KRB5_KDCREP_MODIFIED;
+        else
+            return 0;
+    }
+
+    data.length = rep_s4u_padata->length;
+    data.data = (char *)rep_s4u_padata->contents;
+
+    code = decode_krb5_pa_s4u_x509_user(&data, &rep_s4u_user);
+    if (code != 0)
+        goto cleanup;
+
+    if (rep_s4u_user->user_id.nonce != req_s4u_user->user_id.nonce) {
+        code = KRB5_KDCREP_MODIFIED;
+        goto cleanup;
+    }
+
+    code = encode_krb5_s4u_userid(&rep_s4u_user->user_id, &datap);
+    if (code != 0)
+        goto cleanup;
+
+    if (rep_s4u_user->user_id.options & KRB5_S4U_OPTS_USE_REPLY_KEY_USAGE)
+        usage = KRB5_KEYUSAGE_PA_S4U_X509_USER_REPLY;
+    else
+        usage = KRB5_KEYUSAGE_PA_S4U_X509_USER_REQUEST;
+
+    code = krb5_c_verify_checksum(context, subkey, usage, datap,
+                                  &rep_s4u_user->cksum, &valid);
+    if (code != 0)
+        goto cleanup;
+    if (valid == FALSE) {
+        code = KRB5_KDCREP_MODIFIED;
+        goto cleanup;
+    }
+
+    /*
+     * KDCs that support KRB5_S4U_OPTS_USE_REPLY_KEY_USAGE also return
+     * S4U enc_padata for older (pre-AES) encryption types only.
+     */
+    if (not_newer) {
+        if (enc_s4u_padata == NULL) {
+            if (rep_s4u_user->user_id.options &
+                    KRB5_S4U_OPTS_USE_REPLY_KEY_USAGE) {
+                code = KRB5_KDCREP_MODIFIED;
+                goto cleanup;
+            }
+        } else {
+            if (enc_s4u_padata->length !=
+                req_s4u_user->cksum.length + rep_s4u_user->cksum.length) {
+                code = KRB5_KDCREP_MODIFIED;
+                goto cleanup;
+            }
+            if (memcmp(enc_s4u_padata->contents,
+                       req_s4u_user->cksum.contents,
+                       req_s4u_user->cksum.length) ||
+                memcmp(&enc_s4u_padata->contents[req_s4u_user->cksum.length],
+                       rep_s4u_user->cksum.contents,
+                       rep_s4u_user->cksum.length)) {
+                code = KRB5_KDCREP_MODIFIED;
+                goto cleanup;
+            }
+        }
+    } else if (!krb5_c_is_keyed_cksum(rep_s4u_user->cksum.checksum_type)) {
+        code = KRB5KRB_AP_ERR_INAPP_CKSUM;
+        goto cleanup;
+    }
+
+cleanup:
+    krb5_free_pa_s4u_x509_user(context, rep_s4u_user);
+    krb5_free_data(context, datap);
+
+    return code;
+}
+
+static krb5_error_code
+krb5_get_self_cred_from_kdc(krb5_context context,
+                            krb5_flags options,
+                            krb5_ccache ccache,
+                            krb5_creds *in_creds,
+                            krb5_data *subject_cert,
+                            krb5_data *user_realm,
+                            krb5_creds **out_creds)
+{
+    krb5_error_code code;
+    krb5_principal tgs = NULL;
+    krb5_creds tgtq, s4u_creds, *tgt = NULL, *tgtptr;
+    krb5_creds *referral_tgts[KRB5_REFERRAL_MAXHOPS];
+    krb5_pa_s4u_x509_user s4u_user;
+    int referral_count = 0, i;
+    krb5_flags kdcopt;
+
+    memset(&tgtq, 0, sizeof(tgtq));
+    memset(&s4u_creds, 0, sizeof(s4u_creds));
+    memset(referral_tgts, 0, sizeof(referral_tgts));
+    *out_creds = NULL;
+
+    memset(&s4u_user, 0, sizeof(s4u_user));
+
+    if (in_creds->client != NULL &&
+        krb5_princ_size(context, in_creds->client)) {
+        if (krb5_princ_type(context, in_creds->client) ==
+            KRB5_NT_ENTERPRISE_PRINCIPAL)
+        {
+            code = krb5_build_principal_ext(context,
+                                            &s4u_user.user_id.user,
+                                            user_realm->length,
+                                            user_realm->data,
+                                            in_creds->client->data[0].length,
+                                            in_creds->client->data[0].data,
+                                            0);
+            if (code != 0)
+                goto cleanup;
+            s4u_user.user_id.user->type = KRB5_NT_ENTERPRISE_PRINCIPAL;
+        } else {
+            code = krb5_copy_principal(context,
+                                       in_creds->client,
+                                       &s4u_user.user_id.user);
+            if (code != 0)
+                goto cleanup;
+        }
+    } else {
+        code = krb5_build_principal_ext(context, &s4u_user.user_id.user,
+                                        user_realm->length,
+                                        user_realm->data);
+        if (code != 0)
+            goto cleanup;
+        s4u_user.user_id.user->type = KRB5_NT_ENTERPRISE_PRINCIPAL;
+    }
+    if (subject_cert != NULL)
+        s4u_user.user_id.subject_cert = *subject_cert;
+    s4u_user.user_id.options = KRB5_S4U_OPTS_USE_REPLY_KEY_USAGE;
+
+    /* First, acquire a TGT to the user's realm. */
+    code = krb5_tgtname(context, user_realm,
+                        krb5_princ_realm(context, in_creds->server), &tgs);
+    if (code != 0)
+        goto cleanup;
+
+    tgtq.client = in_creds->server;
+    tgtq.server = tgs;
+
+    code = krb5_get_credentials(context, options, ccache, &tgtq, &tgt);
+    if (code != 0)
+        goto cleanup;
+
+    tgtptr = tgt;
+
+    code = krb5int_copy_creds_contents(context, in_creds, &s4u_creds);
+    if (code != 0)
+        goto cleanup;
+
+    if (s4u_creds.client != NULL) {
+        krb5_free_principal(context, s4u_creds.client);
+        s4u_creds.client = NULL;
+    }
+
+    code = krb5_copy_principal(context, in_creds->server, &s4u_creds.client);
+    if (code != 0)
+        goto cleanup;
+
+    /* Then, walk back the referral path to S4U2Self for user */
+    kdcopt = 0;
+    if (options & KRB5_GC_CANONICALIZE)
+        kdcopt |= KDC_OPT_CANONICALIZE;
+    if (options & KRB5_GC_FORWARDABLE)
+        kdcopt |= KDC_OPT_FORWARDABLE;
+    if (options & KRB5_GC_NO_TRANSIT_CHECK)
+        kdcopt |= KDC_OPT_DISABLE_TRANSITED_CHECK;
+
+    for (referral_count = 0;
+         referral_count < KRB5_REFERRAL_MAXHOPS;
+         referral_count++)
+    {
+        krb5_pa_data **in_padata = NULL;
+        krb5_pa_data **out_padata = NULL;
+        krb5_pa_data **enc_padata = NULL;
+        krb5_keyblock *subkey = NULL;
+
+        if (s4u_user.user_id.user != NULL &&
+            krb5_princ_size(context, s4u_user.user_id.user)) {
+            in_padata = calloc(2, sizeof(krb5_pa_data *));
+            if (in_padata == NULL) {
+                code = ENOMEM;
+                goto cleanup;
+            }
+            code = build_pa_for_user(context,
+                                     tgtptr,
+                                     &s4u_user.user_id, &in_padata[0]);
+            if (code != 0) {
+                krb5_free_pa_data(context, in_padata);
+                goto cleanup;
+            }
+        }
+
+        /* Rewrite server realm to match TGS realm */
+        krb5_free_data_contents(context, &s4u_creds.server->realm);
+
+        code = krb5int_copy_data_contents(context,
+                                          &tgtptr->server->data[1],
+                                          &s4u_creds.server->realm);
+        if (code != 0)
+            goto cleanup;
+
+        code = krb5_get_cred_via_tkt_ext(context, tgtptr,
+                                         KDC_OPT_CANONICALIZE |
+                                         FLAGS2OPTS(tgtptr->ticket_flags) |
+                                         kdcopt,
+                                         tgtptr->addresses,
+                                         in_padata, &s4u_creds,
+                                         build_pa_s4u_x509_user, &s4u_user,
+                                         &out_padata, &enc_padata,
+                                         out_creds, &subkey);
+        if (code != 0) {
+            krb5_free_checksum_contents(context, &s4u_user.cksum);
+            krb5_free_pa_data(context, in_padata);
+            goto cleanup;
+        }
+
+        code = verify_s4u2self_reply(context, subkey, &s4u_user,
+                                     out_padata, enc_padata);
+
+        krb5_free_checksum_contents(context, &s4u_user.cksum);
+        krb5_free_pa_data(context, in_padata);
+        krb5_free_pa_data(context, out_padata);
+        krb5_free_pa_data(context, enc_padata);
+        krb5_free_keyblock(context, subkey);
+
+        if (code != 0)
+            goto cleanup;
+
+        if (krb5_principal_compare(context,
+                                   in_creds->server,
+                                   (*out_creds)->server)) {
+            code = 0;
+            goto cleanup;
+        } else if (IS_TGS_PRINC(context, (*out_creds)->server)) {
+            krb5_data *r1 = &tgtptr->server->data[1];
+            krb5_data *r2 = &(*out_creds)->server->data[1];
+
+            if (data_eq(*r1, *r2)) {
+                krb5_free_creds(context, *out_creds);
+                *out_creds = NULL;
+                code = KRB5_ERR_HOST_REALM_UNKNOWN;
+                break;
+            }
+            for (i = 0; i < referral_count; i++) {
+                if (krb5_principal_compare(context,
+                                           (*out_creds)->server,
+                                           referral_tgts[i]->server)) {
+                    code = KRB5_KDC_UNREACH;
+                    goto cleanup;
+                }
+            }
+
+            tgtptr = *out_creds;
+            referral_tgts[referral_count] = *out_creds;
+            *out_creds = NULL;
+        } else {
+            krb5_free_creds(context, *out_creds);
+            *out_creds = NULL;
+            code = KRB5KRB_AP_WRONG_PRINC; /* XXX */
+            break;
+        }
+    }
+
+cleanup:
+    for (i = 0; i < KRB5_REFERRAL_MAXHOPS; i++) {
+        if (referral_tgts[i] != NULL)
+            krb5_free_creds(context, referral_tgts[i]);
+    }
+    krb5_free_principal(context, tgs);
+    krb5_free_creds(context, tgt);
+    krb5_free_cred_contents(context, &s4u_creds);
+    krb5_free_principal(context, s4u_user.user_id.user);
+    krb5_free_checksum_contents(context, &s4u_user.cksum);
+
+    return code;
+}
+
+krb5_error_code KRB5_CALLCONV
+krb5_get_credentials_for_user(krb5_context context, krb5_flags options,
+                              krb5_ccache ccache, krb5_creds *in_creds,
+                              krb5_data *subject_cert,
+                              krb5_creds **out_creds)
+{
+    krb5_error_code code;
+    krb5_principal realm = NULL;
+
+    *out_creds = NULL;
+
+    if (options & KRB5_GC_CONSTRAINED_DELEGATION) {
+        code = EINVAL;
+        goto cleanup;
+    }
+
+    if (in_creds->client != NULL) {
+        /* Uncanonicalised check */
+        code = krb5_get_credentials(context, options | KRB5_GC_CACHED,
+                                    ccache, in_creds, out_creds);
+        if (code != KRB5_CC_NOTFOUND && code != KRB5_CC_NOT_KTYPE)
+            goto cleanup;
+
+        if ((options & KRB5_GC_CACHED) && !(options & KRB5_GC_CANONICALIZE))
+            goto cleanup;
+    }
+
+    code = s4u_identify_user(context, in_creds, subject_cert, &realm);
+    if (code != 0)
+        goto cleanup;
+
+    code = krb5_get_credentials(context, options | KRB5_GC_CACHED,
+                                ccache, in_creds, out_creds);
+    if ((code != KRB5_CC_NOTFOUND && code != KRB5_CC_NOT_KTYPE)
+        || options & KRB5_GC_CACHED)
+        goto cleanup;
+
+    code = krb5_get_self_cred_from_kdc(context, options, ccache,
+                                       in_creds, subject_cert,
+                                       krb5_princ_realm(context, realm),
+                                       out_creds);
+    if (code != 0)
+        goto cleanup;
+
+    assert(*out_creds != NULL);
+
+    if ((options & KRB5_GC_NO_STORE) == 0) {
+        code = krb5_cc_store_cred(context, ccache, *out_creds);
+        if (code != 0)
+            goto cleanup;
+    }
+
+cleanup:
+    if (code != 0 && *out_creds != NULL) {
+        krb5_free_creds(context, *out_creds);
+        *out_creds = NULL;
+    }
+
+    krb5_free_principal(context, realm);
+
+    return code;
+}
+
+/*
+ * Exported API for constrained delegation (S4U2Proxy).
+ *
+ * This is preferable to using krb5_get_credentials directly because
+ * it can perform some additional checks.
+ */
+krb5_error_code KRB5_CALLCONV
+krb5_get_credentials_for_proxy(krb5_context context,
+                               krb5_flags options,
+                               krb5_ccache ccache,
+                               krb5_creds *in_creds,
+                               krb5_ticket *evidence_tkt,
+                               krb5_creds **out_creds)
+{
+    krb5_error_code code;
+    krb5_creds mcreds;
+    krb5_creds *ncreds = NULL;
+    krb5_flags fields;
+    krb5_data *evidence_tkt_data = NULL;
+    krb5_creds s4u_creds;
+
+    *out_creds = NULL;
+
+    if (in_creds == NULL || in_creds->client == NULL ||
+        evidence_tkt == NULL || evidence_tkt->enc_part2 == NULL) {
+        code = EINVAL;
+        goto cleanup;
+    }
+
+    /*
+     * Caller should have set in_creds->client to match evidence
+     * ticket client
+     */
+    if (!krb5_principal_compare(context, evidence_tkt->enc_part2->client,
+                                in_creds->client)) {
+        code = EINVAL;
+        goto cleanup;
+    }
+
+    if ((evidence_tkt->enc_part2->flags & TKT_FLG_FORWARDABLE) == 0) {
+        code = KRB5_TKT_NOT_FORWARDABLE;
+        goto cleanup;
+    }
+
+    code = krb5_get_credentials_core(context, options, in_creds,
+                                     &mcreds, &fields);
+    if (code != 0)
+        goto cleanup;
+
+    ncreds = calloc(1, sizeof(*ncreds));
+    if (ncreds == NULL) {
+        code = ENOMEM;
+        goto cleanup;
+    }
+    ncreds->magic = KV5M_CRED;
+
+    code = krb5_cc_retrieve_cred(context, ccache, fields, &mcreds, ncreds);
+    if (code != 0) {
+        free(ncreds);
+        ncreds = in_creds;
+    } else {
+        *out_creds = ncreds;
+    }
+
+    if ((code != KRB5_CC_NOTFOUND && code != KRB5_CC_NOT_KTYPE)
+        || options & KRB5_GC_CACHED)
+        goto cleanup;
+
+    code = encode_krb5_ticket(evidence_tkt, &evidence_tkt_data);
+    if (code != 0)
+        goto cleanup;
+
+    s4u_creds = *in_creds;
+    s4u_creds.client = evidence_tkt->server;
+    s4u_creds.second_ticket = *evidence_tkt_data;
+
+    code = krb5_get_credentials(context,
+                                options | KRB5_GC_CONSTRAINED_DELEGATION,
+                                ccache,
+                                &s4u_creds,
+                                out_creds);
+    if (code != 0)
+        goto cleanup;
+
+    /*
+     * Check client name because we couldn't compare that inside
+     * krb5_get_credentials() (enc_part2 is unavailable in clear)
+     */
+    if (!krb5_principal_compare(context,
+                                evidence_tkt->enc_part2->client,
+                                (*out_creds)->client)) {
+        code = KRB5_KDCREP_MODIFIED;
+        goto cleanup;
+    }
+
+cleanup:
+    if (*out_creds != NULL && code != 0) {
+        krb5_free_creds(context, *out_creds);
+        *out_creds = NULL;
+    }
+    if (evidence_tkt_data != NULL)
+        krb5_free_data(context, evidence_tkt_data);
+
+    return code;
+}
diff --git a/src/lib/krb5/krb/send_tgs.c b/src/lib/krb5/krb/send_tgs.c
index 97cd02bf7..eee47ed57 100644
--- a/src/lib/krb5/krb/send_tgs.c
+++ b/src/lib/krb5/krb/send_tgs.c
@@ -77,7 +77,7 @@ tgs_construct_tgsreq(krb5_context context, krb5_data *in_data,
 	if (retval)
 	    goto cleanup;
     }
-    
+
     /* Generate checksum */
     if ((retval = krb5_c_make_checksum(context, cksumtype,
                        &in_cred->keyblock,
@@ -142,6 +142,9 @@ cleanup:
 }
 /*
  * Note that this function fills in part of rep even on failure.
+ *
+ * The pacb_fct callback allows the caller access to the nonce
+ * and request subkey, for binding preauthentication data
  */
 krb5_error_code
 krb5int_send_tgs(krb5_context context, krb5_flags kdcoptions,
@@ -149,7 +152,13 @@ krb5int_send_tgs(krb5_context context, krb5_flags kdcoptions,
           krb5_const_principal sname, krb5_address *const *addrs,
           krb5_authdata *const *authorization_data,
           krb5_pa_data *const *padata, const krb5_data *second_ticket,
-          krb5_creds *in_cred, krb5_response *rep, krb5_keyblock **subkey)
+          krb5_creds *in_cred,
+          krb5_error_code (*pacb_fct)(krb5_context,
+                                      krb5_keyblock *,
+                                      krb5_kdc_req *,
+                                      void *),
+          void *pacb_data,
+          krb5_response *rep, krb5_keyblock **subkey)
 {
     krb5_error_code retval;
     krb5_kdc_req tgsreq;
@@ -157,13 +166,14 @@ krb5int_send_tgs(krb5_context context, krb5_flags kdcoptions,
     krb5_ticket *sec_ticket = 0;
     krb5_ticket *sec_ticket_arr[2];
     krb5_timestamp time_now;
-    krb5_pa_data **combined_padata;
+    krb5_pa_data **combined_padata = NULL;
     krb5_pa_data ap_req_padata;
     int tcp_only = 0, use_master;
     krb5_keyblock *local_subkey = NULL;
 
     assert (subkey != NULL);
     *subkey  = NULL;
+
     /* 
      * in_creds MUST be a valid credential NOT just a partially filled in
      * place holder for us to get credentials for the caller.
@@ -215,8 +225,8 @@ krb5int_send_tgs(krb5_context context, krb5_flags kdcoptions,
 
     /* Get the encryption types list */
     if (ktypes) {
-    /* Check passed ktypes and make sure they're valid. */
-       for (tgsreq.nktypes = 0; ktypes[tgsreq.nktypes]; tgsreq.nktypes++) {
+        /* Check passed ktypes and make sure they're valid. */
+        for (tgsreq.nktypes = 0; ktypes[tgsreq.nktypes]; tgsreq.nktypes++) {
             if (!krb5_c_valid_enctype(ktypes[tgsreq.nktypes]))
                 return KRB5_PROG_ETYPE_NOSUPP;
         }
@@ -236,6 +246,8 @@ krb5int_send_tgs(krb5_context context, krb5_flags kdcoptions,
     } else
         tgsreq.second_ticket = 0;
 
+    ap_req_padata.contents = NULL;
+
     /* encode the body; then checksum it */
     if ((retval = encode_krb5_kdc_req_body(&tgsreq, &scratch)))
         goto send_tgs_error_2;
@@ -250,47 +262,74 @@ krb5int_send_tgs(krb5_context context, krb5_flags kdcoptions,
     }
     krb5_free_data(context, scratch);
 
-    ap_req_padata.pa_type = KRB5_PADATA_AP_REQ;
-    ap_req_padata.length = scratch2.length;
-    ap_req_padata.contents = (krb5_octet *)scratch2.data;
-
-    /* combine in any other supplied padata */
+    tgsreq.padata = (krb5_pa_data **)calloc(2, sizeof(krb5_pa_data *));
+    if (tgsreq.padata == NULL) {
+        free(scratch2.data);
+        goto send_tgs_error_2;
+    }
+    tgsreq.padata[0] = (krb5_pa_data *)malloc(sizeof(krb5_pa_data));
+    if (tgsreq.padata[0] == NULL) {
+        free(scratch2.data);
+        goto send_tgs_error_2;
+    }
+    tgsreq.padata[0]->pa_type = KRB5_PADATA_AP_REQ;
+    tgsreq.padata[0]->length = scratch2.length;
+    tgsreq.padata[0]->contents = (krb5_octet *)scratch2.data;
+    tgsreq.padata[1] = NULL;
+
+    /* combine in any other supplied padata, unfortunately now it is
+     * necessary to copy it as the callback function might modify the
+     * padata, and having a separate path for the non-callback case,
+     * or attempting to determine which elements were changed by the
+     * callback, would have complicated the code significantly.
+     */
     if (padata) {
-        krb5_pa_data * const * counter;
-        register unsigned int i = 0;
-        for (counter = padata; *counter; counter++, i++);
-        combined_padata = malloc((i+2) * sizeof(*combined_padata));
-        if (!combined_padata) {
-            free(ap_req_padata.contents);
-            retval = ENOMEM;
-            goto send_tgs_error_2;
-        }
-        combined_padata[0] = &ap_req_padata;
-        for (i = 1, counter = padata; *counter; counter++, i++)
-            combined_padata[i] = (krb5_pa_data *) *counter;
-        combined_padata[i] = 0;
-    } else {
-        combined_padata = (krb5_pa_data **)malloc(2*sizeof(*combined_padata));
-        if (!combined_padata) {
-            free(ap_req_padata.contents);
-            retval = ENOMEM;
+        krb5_pa_data **tmp;
+        int i;
+
+        for (i = 0; padata[i]; i++)
+            ;
+
+        tmp = (krb5_pa_data **)realloc(tgsreq.padata,
+                                       (i + 2) * sizeof(*combined_padata));
+        if (tmp == NULL)
             goto send_tgs_error_2;
+
+        tgsreq.padata = tmp;
+
+        for (i = 0; padata[i]; i++) {
+            krb5_pa_data *pa;
+
+            pa = tgsreq.padata[1 + i] = (krb5_pa_data *)malloc(sizeof(krb5_pa_data));
+            if (tgsreq.padata == NULL) {
+                retval = ENOMEM;
+                goto send_tgs_error_2;
+            }
+
+            pa->pa_type = padata[i]->pa_type;
+            pa->length = padata[i]->length;
+            pa->contents = (krb5_octet *)malloc(padata[i]->length);
+            if (pa->contents == NULL) {
+                retval = ENOMEM;
+                goto send_tgs_error_2;
+            }
+            memcpy(pa->contents, padata[i]->contents, padata[i]->length);
         }
-        combined_padata[0] = &ap_req_padata;
-        combined_padata[1] = 0;
+        tgsreq.padata[1 + i] = NULL;
     }
-    tgsreq.padata = combined_padata;
 
+    if (pacb_fct != NULL) {
+        if ((retval = (*pacb_fct)(context, local_subkey, &tgsreq, pacb_data)))
+            goto send_tgs_error_2;
+    }
     /* the TGS_REQ is assembled in tgsreq, so encode it */
-    if ((retval = encode_krb5_tgs_req(&tgsreq, &scratch))) {
-        free(ap_req_padata.contents);
-        free(combined_padata);
+    if ((retval = encode_krb5_tgs_req(&tgsreq, &scratch)))
         goto send_tgs_error_2;
-    }
-    free(ap_req_padata.contents);
-    free(combined_padata);
 
     /* now send request & get response from KDC */
+    krb5_free_pa_data(context, tgsreq.padata);
+    tgsreq.padata = NULL;
+
 send_again:
     use_master = 0;
     retval = krb5_sendto_kdc(context, scratch, 
@@ -325,6 +364,8 @@ send_again:
     krb5_free_data(context, scratch);
     
 send_tgs_error_2:;
+    if (tgsreq.padata)
+        krb5_free_pa_data(context, tgsreq.padata);
     if (sec_ticket) 
         krb5_free_ticket(context, sec_ticket);
 
diff --git a/src/lib/krb5/krb/srv_dec_tkt.c b/src/lib/krb5/krb/srv_dec_tkt.c
index b5cf260f2..0934e27e1 100644
--- a/src/lib/krb5/krb/srv_dec_tkt.c
+++ b/src/lib/krb5/krb/srv_dec_tkt.c
@@ -70,27 +70,70 @@ krb5int_server_decrypt_ticket_keyblock(krb5_context context,
 }
 
 
-krb5_error_code	KRB5_CALLCONV
+krb5_error_code KRB5_CALLCONV
 krb5_server_decrypt_ticket_keytab(krb5_context context,
-				  const krb5_keytab kt,
+				  const krb5_keytab keytab,
 				  krb5_ticket *ticket)
 {
-    krb5_error_code       retval;
-    krb5_enctype          enctype;
-    krb5_keytab_entry     ktent;
+    krb5_error_code 	  retval;
+    krb5_keytab_entry 	  ktent;
+
+    retval = KRB5_KT_NOTFOUND;
+
+    if (keytab->ops->start_seq_get == NULL) {
+	retval = krb5_kt_get_entry(context, keytab,
+				   ticket->server,
+				   ticket->enc_part.kvno,
+				   ticket->enc_part.enctype, &ktent);
+	if (retval == 0) {
+	    retval = krb5int_server_decrypt_ticket_keyblock(context, &ktent.key, ticket);
+
+	    (void) krb5_free_keytab_entry_contents(context, &ktent);
+	}
+    } else {
+	krb5_error_code code;
+	krb5_kt_cursor cursor;
+
+	retval = krb5_kt_start_seq_get(context, keytab, &cursor);
+	if (retval != 0)
+	    goto map_error;
 
-    enctype = ticket->enc_part.enctype;
+	while ((code = krb5_kt_next_entry(context, keytab,
+					  &ktent, &cursor)) == 0) {
+	    if (ktent.key.enctype != ticket->enc_part.enctype)
+		continue;
 
-    if ((retval = krb5_kt_get_entry(context, kt, ticket->server,
-                                    ticket->enc_part.kvno,
-                                    enctype, &ktent)))
-        return retval;
+	    retval = krb5int_server_decrypt_ticket_keyblock(context, &ktent.key, ticket);
+	    if (retval == 0) {
+		krb5_principal tmp;
 
-    retval = krb5int_server_decrypt_ticket_keyblock(context,
-						    &ktent.key, ticket);
-    /* Upon error, Free keytab entry first, then return */
+		retval = krb5_copy_principal(context, ktent.principal, &tmp);
+		if (retval == 0) {
+		    krb5_free_principal(context, ticket->server);
+		    ticket->server = tmp;
+		}
+		(void) krb5_free_keytab_entry_contents(context, &ktent);
+		break;
+	    }
+	    (void) krb5_free_keytab_entry_contents(context, &ktent);
+	}
+
+	code = krb5_kt_end_seq_get(context, keytab, &cursor);
+	if (code != 0)
+	    retval = code;
+    }
+
+map_error:
+    switch (retval) {
+    case KRB5_KT_KVNONOTFOUND:
+    case KRB5_KT_NOTFOUND:
+    case KRB5KRB_AP_ERR_BAD_INTEGRITY:
+	retval = KRB5KRB_AP_WRONG_PRINC;
+	break;
+    default:
+	break;
+    }
 
-    (void) krb5_kt_free_entry(context, &ktent);
     return retval;
 }
 #endif /* LEAN_CLIENT */
diff --git a/src/lib/krb5/libkrb5.exports b/src/lib/krb5/libkrb5.exports
index bd50fddb5..b809e83cf 100644
--- a/src/lib/krb5/libkrb5.exports
+++ b/src/lib/krb5/libkrb5.exports
@@ -20,11 +20,12 @@ decode_krb5_error
 decode_krb5_etype_info
 decode_krb5_etype_info2
 decode_krb5_fast_req
-decode_krb5_pa_fx_fast_request
 decode_krb5_kdc_req_body
 decode_krb5_pa_enc_ts
 decode_krb5_pa_for_user
+decode_krb5_pa_fx_fast_request
 decode_krb5_pa_pac_req
+decode_krb5_pa_s4u_x509_user
 decode_krb5_padata_sequence
 decode_krb5_predicted_sam_response
 decode_krb5_priv
@@ -60,10 +61,11 @@ encode_krb5_error
 encode_krb5_etype_info
 encode_krb5_etype_info2
 encode_krb5_fast_response
-encode_krb5_pa_fx_fast_reply
 encode_krb5_kdc_req_body
 encode_krb5_pa_enc_ts
 encode_krb5_pa_for_user
+encode_krb5_pa_fx_fast_reply
+encode_krb5_pa_s4u_x509_user
 encode_krb5_pa_server_referral_data
 encode_krb5_pa_svr_referral_data
 encode_krb5_padata_sequence
@@ -71,6 +73,7 @@ encode_krb5_predicted_sam_response
 encode_krb5_priv
 encode_krb5_pwd_data
 encode_krb5_pwd_sequence
+encode_krb5_s4u_userid
 encode_krb5_safe
 encode_krb5_sam_challenge
 encode_krb5_sam_key
@@ -134,9 +137,9 @@ krb5_auth_con_setsendsubkey
 krb5_auth_con_setuseruserkey
 krb5_auth_to_rep
 krb5_build_principal
+krb5_build_principal_alloc_va
 krb5_build_principal_ext
 krb5_build_principal_va
-krb5_build_principal_alloc_va
 krb5_cc_close
 krb5_cc_copy_creds
 krb5_cc_default
@@ -243,8 +246,9 @@ krb5_free_ktypes
 krb5_free_last_req
 krb5_free_pa_data
 krb5_free_pa_enc_ts
-krb5_free_pa_pac_req
 krb5_free_pa_for_user
+krb5_free_pa_pac_req
+krb5_free_pa_s4u_x509_user
 krb5_free_pa_server_referral_data
 krb5_free_pa_svr_referral_data
 krb5_free_passwd_phrase_element
@@ -284,6 +288,8 @@ krb5_get_cred_from_kdc_renew
 krb5_get_cred_from_kdc_validate
 krb5_get_cred_via_tkt
 krb5_get_credentials
+krb5_get_credentials_for_proxy
+krb5_get_credentials_for_user
 krb5_get_credentials_renew
 krb5_get_credentials_validate
 krb5_get_default_config_files
@@ -380,7 +386,6 @@ krb5_os_free_context
 krb5_os_hostaddr
 krb5_os_init_context
 krb5_os_localaddr
-krb5int_get_domain_realm_mapping
 krb5_overridekeyname
 krb5_pac_add_buffer
 krb5_pac_free
@@ -529,6 +534,7 @@ krb5int_find_authdata
 krb5int_find_pa_data
 krb5int_foreach_localaddr
 krb5int_free_addrlist
+krb5int_get_domain_realm_mapping
 krb5int_init_context_kdc
 krb5int_initialize_library
 krb5int_pac_sign
diff --git a/src/lib/krb5/os/sendto_kdc.c b/src/lib/krb5/os/sendto_kdc.c
index dcf08d996..3e5f9e234 100644
--- a/src/lib/krb5/os/sendto_kdc.c
+++ b/src/lib/krb5/os/sendto_kdc.c
@@ -57,7 +57,7 @@
 #define DEFAULT_UDP_PREF_LIMIT	 1465
 #define HARD_UDP_LIMIT		32700 /* could probably do 64K-epsilon ? */
 
-#undef DEBUG
+#define DEBUG 1
 
 #ifdef DEBUG
 int krb5int_debug_sendto_kdc = 0;
diff --git a/src/slave/kproplog.c b/src/slave/kproplog.c
index 43a7738d4..6fb2e2288 100644
--- a/src/slave/kproplog.c
+++ b/src/slave/kproplog.c
@@ -40,23 +40,31 @@ static void
 print_flags(unsigned int flags)
 {
     unsigned int i;
-    static char *prflags[] = { 
-	"DISALLOW_POSTDATED",   /* 0x00000001 */ 
-	"DISALLOW_FORWARDABLE", /* 0x00000002 */ 
-	"DISALLOW_TGT_BASED",   /* 0x00000004 */ 
-	"DISALLOW_RENEWABLE",   /* 0x00000008 */ 
-	"DISALLOW_PROXIABLE",   /* 0x00000010 */ 
-	"DISALLOW_DUP_SKEY",    /* 0x00000020 */ 
-	"DISALLOW_ALL_TIX",     /* 0x00000040 */ 
-	"REQUIRES_PRE_AUTH",    /* 0x00000080 */ 
-	"REQUIRES_HW_AUTH",     /* 0x00000100 */ 
-	"REQUIRES_PWCHANGE",    /* 0x00000200 */ 
-	"UNKNOWN_0x00000400",   /* 0x00000400 */ 
-	"UNKNOWN_0x00000800",   /* 0x00000800 */ 
-	"DISALLOW_SVR",         /* 0x00001000 */ 
-	"PWCHANGE_SERVICE",     /* 0x00002000 */ 
-	"SUPPORT_DESMD5",       /* 0x00004000 */ 
-	"NEW_PRINC",            /* 0x00008000 */ 
+    static char *prflags[] = {
+	"DISALLOW_POSTDATED",     /* 0x00000001 */
+	"DISALLOW_FORWARDABLE",   /* 0x00000002 */
+	"DISALLOW_TGT_BASED",     /* 0x00000004 */
+	"DISALLOW_RENEWABLE",     /* 0x00000008 */
+	"DISALLOW_PROXIABLE",     /* 0x00000010 */
+	"DISALLOW_DUP_SKEY",      /* 0x00000020 */
+	"DISALLOW_ALL_TIX",       /* 0x00000040 */
+	"REQUIRES_PRE_AUTH",      /* 0x00000080 */
+	"REQUIRES_HW_AUTH",       /* 0x00000100 */
+	"REQUIRES_PWCHANGE",      /* 0x00000200 */
+	"UNKNOWN_0x00000400",     /* 0x00000400 */
+	"UNKNOWN_0x00000800",     /* 0x00000800 */
+	"DISALLOW_SVR",           /* 0x00001000 */
+	"PWCHANGE_SERVICE",       /* 0x00002000 */
+	"SUPPORT_DESMD5",         /* 0x00004000 */
+	"NEW_PRINC",              /* 0x00008000 */
+	"UNKNOWN_0x00010000",     /* 0x00010000 */
+	"UNKNOWN_0x00020000",     /* 0x00020000 */
+	"UNKNOWN_0x00040000",     /* 0x00040000 */
+	"UNKNOWN_0x00080000",     /* 0x00080000 */
+	"OK_AS_DELEGATE",         /* 0x00100000 */
+	"OK_TO_AUTH_AS_DELEGATE", /* 0x00200000 */
+	"NO_AUTH_DATA_REQUIRED",  /* 0x00400000 */
+
     };
 
     for (i = 0; i < sizeof (prflags) / sizeof (char *); i++) {
@@ -169,7 +177,7 @@ print_key(kdbe_key_t *k)
 
     for (i = 0; i < k->k_enctype.k_enctype_len; i++) {
 	printf("\t\t\tenc type: 0x%x\n",
-	       k->k_enctype.k_enctype_val[i]); 
+	       k->k_enctype.k_enctype_val[i]);
     }
 
     str = k->k_contents.k_contents_val;
diff --git a/src/tests/asn.1/krb5_decode_leak.c b/src/tests/asn.1/krb5_decode_leak.c
index 41045b5a8..be0a536e9 100644
--- a/src/tests/asn.1/krb5_decode_leak.c
+++ b/src/tests/asn.1/krb5_decode_leak.c
@@ -658,7 +658,18 @@ main(int argc, char **argv)
                   krb5_free_enc_sam_response_enc_2);
         ktest_empty_enc_sam_response_enc_2(&sam_ch2);
     }
+    /****************************************************************/
+    /* encode_krb5_pa_s4u_x509_user */
+    {
+        krb5_pa_s4u_x509_user s4u, *tmp;
 
+        setup(s4u, "pa_s4u_x509_user",
+              ktest_make_sample_pa_s4u_x509_user);
+        leak_test(s4u, encode_krb5_pa_s4u_x509_user,
+                  decode_krb5_pa_s4u_x509_user,
+                  krb5_free_pa_s4u_x509_user);
+        ktest_empty_pa_s4u_x509_user(&s4u);
+    }
     krb5_free_context(test_context);
     return 0;
 }
diff --git a/src/tests/asn.1/krb5_decode_test.c b/src/tests/asn.1/krb5_decode_test.c
index 7136669ac..2d2000422 100644
--- a/src/tests/asn.1/krb5_decode_test.c
+++ b/src/tests/asn.1/krb5_decode_test.c
@@ -890,7 +890,13 @@ int main(argc, argv)
 
 	ktest_empty_sam_response(&ref);
     }
-  
+
+    {
+	setup(krb5_pa_s4u_x509_user,"krb5_pa_s4u_x509_user",ktest_make_sample_pa_s4u_x509_user);
+	decode_run("pa_s4u_x509_user","","30 68 A0 55 30 53 A0 06 02 04 00 CA 14 9A A1 1A 30 18 A0 03 02 01 01 A1 11 30 0F 1B 06 68 66 74 73 61 69 1B 05 65 78 74 72 61 A2 10 1B 0E 41 54 48 45 4E 41 2E 4D 49 54 2E 45 44 55 A3 12 04 10 70 61 5F 73 34 75 5F 78 35 30 39 5F 75 73 65 72 A4 07 03 05 00 80 00 00 00 A1 0F 30 0D A0 03 02 01 01 A1 06 04 04 31 32 33 34",decode_krb5_pa_s4u_x509_user,ktest_equal_pa_s4u_x509_user,krb5_free_pa_s4u_x509_user);
+	ktest_empty_pa_s4u_x509_user(&ref);
+    }
+
 #ifdef ENABLE_LDAP
     /* ldap sequence_of_keys */
     {
diff --git a/src/tests/asn.1/krb5_encode_test.c b/src/tests/asn.1/krb5_encode_test.c
index 2da5c1e7f..7ae32ec75 100644
--- a/src/tests/asn.1/krb5_encode_test.c
+++ b/src/tests/asn.1/krb5_encode_test.c
@@ -695,6 +695,18 @@ main(argc, argv)
 		   acc.encode_krb5_enc_sam_response_enc_2);
 	ktest_empty_enc_sam_response_enc_2(&sam_ch2);
     }
+    /****************************************************************/
+    /* encode_krb5_pa_s4u_x509_user */
+    {
+	krb5_pa_s4u_x509_user s4u;
+	setup(s4u,krb5_pa_s4u_x509_user,"pa_s4u_x509_user",
+	      ktest_make_sample_pa_s4u_x509_user);
+	encode_run(s4u,krb5_pa_s4u_x509_user,
+		   "pa_s4u_x509_user","",
+		   encode_krb5_pa_s4u_x509_user);
+	ktest_empty_pa_s4u_x509_user(&s4u);
+    }
+
 #ifdef ENABLE_LDAP
     {
 	ldap_seqof_key_data skd;
diff --git a/src/tests/asn.1/ktest.c b/src/tests/asn.1/ktest.c
index 5951b6c7e..8b6367918 100644
--- a/src/tests/asn.1/ktest.c
+++ b/src/tests/asn.1/ktest.c
@@ -825,6 +825,23 @@ krb5_error_code ktest_make_sample_enc_sam_response_enc_2(p)
     return 0;
 }
 
+krb5_error_code ktest_make_sample_pa_s4u_x509_user(p)
+    krb5_pa_s4u_x509_user *p;
+{
+    krb5_error_code retval;
+    krb5_s4u_userid *u = &p->user_id;
+    u->nonce = 13243546;
+    retval = ktest_make_sample_principal(&u->user);
+    if (retval) return retval;
+    u->subject_cert.data = strdup("pa_s4u_x509_user");
+    if (u->subject_cert.data == NULL) return ENOMEM;
+    u->subject_cert.length = strlen(u->subject_cert.data);
+    u->options = 0x80000000;
+    retval = ktest_make_sample_checksum(&p->cksum);
+    if (retval) return retval;
+    return 0;
+}
+
 #ifdef ENABLE_LDAP
 static krb5_error_code ktest_make_sample_key_data(krb5_key_data *p, int i)
 {
@@ -1420,6 +1437,14 @@ void ktest_empty_enc_sam_response_enc_2(p)
   ktest_empty_data(&p->sam_sad);
 }
 
+void ktest_empty_pa_s4u_x509_user(p)
+    krb5_pa_s4u_x509_user *p;
+{
+    ktest_destroy_principal(&p->user_id.user);
+    ktest_empty_data(&p->user_id.subject_cert);
+    if (p->cksum.contents) free(p->cksum.contents);
+}
+
 #ifdef ENABLE_LDAP
 void ktest_empty_ldap_seqof_key_data(ctx, p)
     krb5_context ctx;
diff --git a/src/tests/asn.1/ktest.h b/src/tests/asn.1/ktest.h
index af7c9acc8..a2951d26f 100644
--- a/src/tests/asn.1/ktest.h
+++ b/src/tests/asn.1/ktest.h
@@ -105,7 +105,7 @@ krb5_error_code ktest_make_sample_enc_sam_response_enc
 	(krb5_enc_sam_response_enc *p);
 krb5_error_code ktest_make_sample_predicted_sam_response(krb5_predicted_sam_response *p);
 krb5_error_code ktest_make_sample_enc_sam_response_enc_2(krb5_enc_sam_response_enc_2 *p);
-
+krb5_error_code ktest_make_sample_pa_s4u_x509_user(krb5_pa_s4u_x509_user *p);
 
 #ifdef ENABLE_LDAP
 krb5_error_code ktest_make_sample_ldap_seqof_key_data(ldap_seqof_key_data * p);
@@ -214,6 +214,7 @@ void ktest_empty_enc_sam_response_enc(krb5_enc_sam_response_enc *p);
 void ktest_empty_predicted_sam_response(krb5_predicted_sam_response *p);
 void ktest_empty_sam_response_2(krb5_sam_response_2 *p);
 void ktest_empty_enc_sam_response_enc_2(krb5_enc_sam_response_enc_2 *p);
+void ktest_empty_pa_s4u_x509_user(krb5_pa_s4u_x509_user *p);
 
 #ifdef ENABLE_LDAP
 void ktest_empty_ldap_seqof_key_data(krb5_context, ldap_seqof_key_data *p);
diff --git a/src/tests/asn.1/ktest_equal.c b/src/tests/asn.1/ktest_equal.c
index 5ec0a01dc..da0324973 100644
--- a/src/tests/asn.1/ktest_equal.c
+++ b/src/tests/asn.1/ktest_equal.c
@@ -542,6 +542,20 @@ int ktest_equal_sam_response(ref, var)
     return p;
 }
 
+int ktest_equal_pa_s4u_x509_user(ref, var)
+    krb5_pa_s4u_x509_user *ref;
+    krb5_pa_s4u_x509_user *var;
+{
+    int p = TRUE;
+    if (ref == var) return TRUE;
+    else if (ref == NULL || var == NULL) return FALSE;
+    p=p&&scalar_equal(user_id.nonce);
+    p=p&&ptr_equal(user_id.user,ktest_equal_principal_data);
+    p=p&&struct_equal(user_id.subject_cert,ktest_equal_data);
+    p=p&&scalar_equal(user_id.options);
+    p=p&&struct_equal(cksum,ktest_equal_checksum);
+    return p;
+}
 #ifdef ENABLE_LDAP
 static int equal_key_data(ref, var)
     krb5_key_data *ref;
diff --git a/src/tests/asn.1/ktest_equal.h b/src/tests/asn.1/ktest_equal.h
index 217272378..8a0641de5 100644
--- a/src/tests/asn.1/ktest_equal.h
+++ b/src/tests/asn.1/ktest_equal.h
@@ -91,6 +91,10 @@ int ktest_equal_krb5_etype_info_entry
     (krb5_etype_info_entry * ref,
 		    krb5_etype_info_entry * var);
 
+int ktest_equal_pa_s4u_x509_user
+    (krb5_pa_s4u_x509_user *ref,
+		    krb5_pa_s4u_x509_user *var);
+
 int ktest_equal_ldap_sequence_of_keys(ldap_seqof_key_data *ref,
 				      ldap_seqof_key_data *var);
 #endif
diff --git a/src/tests/asn.1/reference_encode.out b/src/tests/asn.1/reference_encode.out
index b6ac7fb2d..0d913cdb2 100644
--- a/src/tests/asn.1/reference_encode.out
+++ b/src/tests/asn.1/reference_encode.out
@@ -56,3 +56,4 @@ encode_krb5_enc_sam_response_enc: 30 38 A0 05 02 03 01 33 2A A1 11 18 0F 31 39 3
 encode_krb5_predicted_sam_response: 30 6D A0 13 30 11 A0 03 02 01 01 A1 0A 04 08 31 32 33 34 35 36 37 38 A1 07 03 05 00 00 00 00 09 A2 11 18 0F 31 39 37 30 30 31 30 31 30 30 30 30 31 37 5A A3 03 02 01 12 A4 10 1B 0E 41 54 48 45 4E 41 2E 4D 49 54 2E 45 44 55 A5 1A 30 18 A0 03 02 01 01 A1 11 30 0F 1B 06 68 66 74 73 61 69 1B 05 65 78 74 72 61 A6 07 04 05 68 65 6C 6C 6F
 encode_krb5_sam_response_2: 30 42 A0 03 02 01 2B A1 07 03 05 00 80 00 00 00 A2 0C 04 0A 74 72 61 63 6B 20 64 61 74 61 A3 1D 30 1B A0 03 02 01 01 A1 04 02 02 0D 36 A2 0E 04 0C 6E 6F 6E 63 65 20 6F 72 20 73 61 64 A4 05 02 03 54 32 10
 encode_krb5_enc_sam_response_enc_2: 30 1F A0 03 02 01 58 A1 18 04 16 65 6E 63 5F 73 61 6D 5F 72 65 73 70 6F 6E 73 65 5F 65 6E 63 5F 32
+encode_krb5_pa_s4u_x509_user: 30 68 A0 55 30 53 A0 06 02 04 00 CA 14 9A A1 1A 30 18 A0 03 02 01 01 A1 11 30 0F 1B 06 68 66 74 73 61 69 1B 05 65 78 74 72 61 A2 10 1B 0E 41 54 48 45 4E 41 2E 4D 49 54 2E 45 44 55 A3 12 04 10 70 61 5F 73 34 75 5F 78 35 30 39 5F 75 73 65 72 A4 07 03 05 00 80 00 00 00 A1 0F 30 0D A0 03 02 01 01 A1 06 04 04 31 32 33 34
diff --git a/src/tests/asn.1/trval_reference.out b/src/tests/asn.1/trval_reference.out
index 9c5f8cc1e..c8aa48e3f 100644
--- a/src/tests/asn.1/trval_reference.out
+++ b/src/tests/asn.1/trval_reference.out
@@ -1246,3 +1246,20 @@ encode_krb5_enc_sam_response_enc_2:
 .  [0] [Integer] 88
 .  [1] [Octet String] "enc_sam_response_enc_2"
 
+encode_krb5_pa_s4u_x509_user:
+
+[Sequence/Sequence Of] 
+.  [0] [Sequence/Sequence Of] 
+.  .  [0] [Integer] 13243546
+.  .  [1] [Sequence/Sequence Of] 
+.  .  .  [0] [Integer] 1
+.  .  .  [1] [Sequence/Sequence Of] 
+.  .  .  .  [General string] "hftsai"
+.  .  .  .  [General string] "extra"
+.  .  [2] [General string] "ATHENA.MIT.EDU"
+.  .  [3] [Octet String] "pa_s4u_x509_user"
+.  .  [4] [Bit String] 0x80000000
+.  [1] [Sequence/Sequence Of] 
+.  .  [0] [Integer] 1
+.  .  [1] [Octet String] "1234"
+
diff --git a/src/tests/gssapi/Makefile.in b/src/tests/gssapi/Makefile.in
index d0ea1e137..e385c68f6 100644
--- a/src/tests/gssapi/Makefile.in
+++ b/src/tests/gssapi/Makefile.in
@@ -6,15 +6,18 @@ DEFINES = -DUSE_AUTOCONF_H
 PROG_LIBPATH=-L$(TOPLIBD)
 PROG_RPATH=$(KRB5_LIBDIR)
 
-SRCS= $(srcdir)/t_imp_name.c
+SRCS= $(srcdir)/t_imp_name.c $(srcdir)/t_s4u.c
 
-OBJS= t_imp_name.o
+OBJS= t_imp_name.o t_s4u.o
 
-all:: t_imp_name
+all:: t_imp_name t_s4u
 
 t_imp_name: t_imp_name.o $(GSS_DEPLIBS) $(KRB5_BASE_DEPLIBS)
 	$(CC_LINK) -o t_imp_name t_imp_name.o $(GSS_LIBS) $(KRB5_BASE_LIBS)
 
+t_s4u: t_s4u.o $(GSS_DEPLIBS) $(KRB5_BASE_DEPLIBS)
+	$(CC_LINK) -o t_s4u t_s4u.o $(GSS_LIBS) $(KRB5_BASE_LIBS)
+
 clean::
-	$(RM) t_imp_name
+	$(RM) t_imp_name t_s4u
 
diff --git a/src/tests/gssapi/t_s4u.c b/src/tests/gssapi/t_s4u.c
new file mode 100644
index 000000000..264e60a60
--- /dev/null
+++ b/src/tests/gssapi/t_s4u.c
@@ -0,0 +1,418 @@
+/* -*- mode: c; indent-tabs-mode: nil -*- */
+/*
+ * Copyright 2009  by the Massachusetts Institute of Technology.
+ * All Rights Reserved.
+ *
+ * Export of this software from the United States of America may
+ *   require a specific license from the United States Government.
+ *   It is the responsibility of any person or organization contemplating
+ *   export to obtain such a license before exporting.
+ *
+ * WITHIN THAT CONSTRAINT, permission to use, copy, modify, and
+ * distribute this software and its documentation for any purpose and
+ * without fee is hereby granted, provided that the above copyright
+ * notice appear in all copies and that both that copyright notice and
+ * this permission notice appear in supporting documentation, and that
+ * the name of M.I.T. not be used in advertising or publicity pertaining
+ * to distribution of the software without specific, written prior
+ * permission.  Furthermore if you modify this software you must label
+ * your software as modified software and not distribute it in such a
+ * fashion that it might be confused with the original M.I.T. software.
+ * M.I.T. makes no representations about the suitability of
+ * this software for any purpose.  It is provided "as is" without express
+ * or implied warranty.
+ *
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include <gssapi/gssapi_krb5.h>
+
+/*
+ * Test program for protocol transition (S4U2Self) and constrained delegation
+ * (S4U2Proxy)
+ *
+ * Note: because of name canonicalization, the following tips may help
+ * when configuring with Active Directory:
+ *
+ * - Create a computer account FOO$
+ * - Set the UPN to host/foo.domain (no suffix); this is necessary to
+ *   be able to send an AS-REQ as this principal, otherwise you would
+ *   need to use the canonical name (FOO$), which will cause principal
+ *   comparison errors in gss_accept_sec_context().
+ * - Add a SPN of host/foo.domain
+ * - Configure the computer account to support constrained delegation with
+ *   protocol transition (Trust this computer for delegation to specified
+ *   services only / Use any authentication protocol)
+ * - Add host/foo.domain to the keytab (possibly easiest to do this
+ *   with ktadd)
+ *
+ * For S4U2Proxy to work the TGT must be forwardable too.
+ *
+ * Usage eg:
+ *
+ * kinit -k -t test.keytab -f 'host/test.win.mit.edu@WIN.MIT.EDU'
+ * ./t_s4u delegtest@WIN.MIT.EDU HOST/WIN-EQ7E4AA2WR8.win.mit.edu@WIN.MIT.EDU test.keytab
+ */
+
+static gss_OID_desc spnego_mech = { 6, "\053\006\001\005\005\002" };
+
+int use_spnego = 0;
+
+static void displayStatus_1(m, code, type)
+     char *m;
+     OM_uint32 code;
+     int type;
+{
+     OM_uint32 maj_stat, min_stat;
+     gss_buffer_desc msg;
+     OM_uint32 msg_ctx;
+
+     msg_ctx = 0;
+     while (1) {
+          maj_stat = gss_display_status(&min_stat, code,
+                                       type, GSS_C_NULL_OID,
+                                       &msg_ctx, &msg);
+          fprintf(stderr, "%s: %s\n", m, (char *)msg.value);
+          (void) gss_release_buffer(&min_stat, &msg);
+
+          if (!msg_ctx)
+               break;
+     }
+}
+
+static void displayStatus(msg, maj_stat, min_stat)
+     char *msg;
+     OM_uint32 maj_stat;
+     OM_uint32 min_stat;
+{
+     displayStatus_1(msg, maj_stat, GSS_C_GSS_CODE);
+     displayStatus_1(msg, min_stat, GSS_C_MECH_CODE);
+}
+
+static OM_uint32
+displayCanonName(OM_uint32 *minor, gss_name_t name, char *tag)
+{
+    gss_name_t canon;
+    OM_uint32 major, tmp_minor;
+    gss_buffer_desc buf;
+
+    major = gss_canonicalize_name(minor, name,
+                                  (gss_OID)gss_mech_krb5, &canon);
+    if (GSS_ERROR(major)) {
+        displayStatus("gss_canonicalize_name", major, *minor);
+        return major;
+    }
+
+    major = gss_display_name(minor, canon, &buf, NULL);
+    if (GSS_ERROR(major)) {
+        displayStatus("gss_display_name", major, *minor);
+        gss_release_name(&tmp_minor, &canon);
+        return major;
+    }
+
+    printf("%s:\t%s\n", tag, (char *)buf.value);
+
+    gss_release_buffer(&tmp_minor, &buf);
+    gss_release_name(&tmp_minor, &canon);
+
+    return GSS_S_COMPLETE;
+}
+
+static OM_uint32
+displayOID(OM_uint32 *minor, gss_OID oid, char *tag)
+{
+    OM_uint32 major, tmp_minor;
+    gss_buffer_desc buf;
+
+    major = gss_oid_to_str(minor, oid, &buf);
+    if (GSS_ERROR(major)) {
+        displayStatus("gss_oid_to_str", major, *minor);
+        return major;
+    }
+
+    printf("%s:\t%s\n", tag, (char *)buf.value);
+
+    gss_release_buffer(&tmp_minor, &buf);
+
+    return GSS_S_COMPLETE;
+}
+
+static OM_uint32
+initAcceptSecContext(OM_uint32 *minor,
+                     gss_cred_id_t claimant_cred_handle,
+                     gss_cred_id_t verifier_cred_handle,
+                     gss_cred_id_t *deleg_cred_handle)
+{
+    OM_uint32 major, tmp_minor;
+    gss_buffer_desc token, tmp;
+    gss_ctx_id_t initiator_context = GSS_C_NO_CONTEXT;
+    gss_ctx_id_t acceptor_context = GSS_C_NO_CONTEXT;
+    gss_name_t source_name = GSS_C_NO_NAME;
+    gss_name_t target_name = GSS_C_NO_NAME;
+    OM_uint32 time_rec;
+    gss_OID mech = GSS_C_NO_OID;
+
+    token.value = NULL;
+    token.length = 0;
+
+    tmp.value = NULL;
+    tmp.length = 0;
+
+    *deleg_cred_handle = GSS_C_NO_CREDENTIAL;
+
+    major = gss_inquire_cred(minor, verifier_cred_handle,
+                             &target_name, NULL, NULL, NULL);
+    if (GSS_ERROR(major)) {
+        displayStatus("gss_inquire_cred", major, *minor);
+        return major;
+    }
+
+    displayCanonName(minor, target_name, "Target name");
+
+    mech = use_spnego ? (gss_OID)&spnego_mech : (gss_OID)gss_mech_krb5;
+    displayOID(minor, mech, "Target mech");
+
+    major = gss_init_sec_context(minor,
+                                 claimant_cred_handle,
+                                 &initiator_context,
+                                 target_name,
+                                 mech,
+                                 GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG,
+                                 GSS_C_INDEFINITE,
+                                 GSS_C_NO_CHANNEL_BINDINGS,
+                                 GSS_C_NO_BUFFER,
+                                 NULL,
+                                 &token,
+                                 NULL,
+                                 &time_rec);
+
+    if (target_name != GSS_C_NO_NAME)
+        (void) gss_release_name(&tmp_minor, &target_name);
+
+    if (GSS_ERROR(major)) {
+        displayStatus("gss_init_sec_context", major, *minor);
+        return major;
+    }
+
+    (void) gss_delete_sec_context(minor, &initiator_context, NULL);
+    mech = GSS_C_NO_OID;
+
+    major = gss_accept_sec_context(minor,
+                                   &acceptor_context,
+                                   verifier_cred_handle,
+                                   &token,
+                                   GSS_C_NO_CHANNEL_BINDINGS,
+                                   &source_name,
+                                   &mech,
+                                   &tmp,
+                                   NULL,
+                                   &time_rec,
+                                   deleg_cred_handle);
+
+    if (GSS_ERROR(major))
+        displayStatus("gss_accept_sec_context", major, *minor);
+    else {
+        displayCanonName(minor, source_name, "Source name");
+        displayOID(minor, mech, "Source mech");
+    }
+
+    (void) gss_release_name(&tmp_minor, &source_name);
+    (void) gss_delete_sec_context(&tmp_minor, &acceptor_context, NULL);
+    (void) gss_release_buffer(&tmp_minor, &token);
+    (void) gss_release_buffer(&tmp_minor, &tmp);
+    (void) gss_release_oid(&tmp_minor, &mech);
+
+    return major;
+}
+
+static OM_uint32
+constrainedDelegate(OM_uint32 *minor,
+                    gss_OID_set desired_mechs,
+                    gss_name_t target,
+                    gss_cred_id_t delegated_cred_handle,
+                    gss_cred_id_t verifier_cred_handle)
+{
+    OM_uint32 major, tmp_minor;
+    gss_ctx_id_t initiator_context = GSS_C_NO_CONTEXT;
+    gss_name_t cred_name = GSS_C_NO_NAME;
+    OM_uint32 time_rec, lifetime;
+    gss_cred_usage_t usage;
+    gss_buffer_desc token;
+    gss_OID_set mechs;
+
+    printf("Constrained delegation tests follow\n");
+    printf("-----------------------------------\n\n");
+
+    if (gss_inquire_cred(minor, verifier_cred_handle, &cred_name,
+                         &lifetime, &usage, NULL) == GSS_S_COMPLETE) {
+        displayCanonName(minor, cred_name, "Proxy name");
+        gss_release_name(&tmp_minor, &cred_name);
+    }
+    displayCanonName(minor, target, "Target name");
+    if (gss_inquire_cred(minor, delegated_cred_handle, &cred_name,
+                         &lifetime, &usage, &mechs) == GSS_S_COMPLETE) {
+        displayCanonName(minor, cred_name, "Delegated name");
+        displayOID(minor, &mechs->elements[0], "Delegated mech");
+        gss_release_name(&tmp_minor, &cred_name);
+    }
+
+    printf("\n");
+
+    major = gss_init_sec_context(minor,
+                                 delegated_cred_handle,
+                                 &initiator_context,
+                                 target,
+                                 mechs ? &mechs->elements[0] :
+                                         (gss_OID)gss_mech_krb5,
+                                 GSS_C_REPLAY_FLAG | GSS_C_SEQUENCE_FLAG,
+                                 GSS_C_INDEFINITE,
+                                 GSS_C_NO_CHANNEL_BINDINGS,
+                                 GSS_C_NO_BUFFER,
+                                 NULL,
+                                 &token,
+                                 NULL,
+                                 &time_rec);
+    if (GSS_ERROR(major))
+        displayStatus("gss_init_sec_context", major, *minor);
+
+    (void) gss_release_buffer(&tmp_minor, &token);
+    (void) gss_delete_sec_context(&tmp_minor, &initiator_context, NULL);
+    (void) gss_release_oid_set(&tmp_minor, &mechs);
+
+    return major;
+}
+
+int main(int argc, char *argv[])
+{
+    OM_uint32 minor, major;
+    gss_cred_id_t impersonator_cred_handle = GSS_C_NO_CREDENTIAL;
+    gss_cred_id_t user_cred_handle = GSS_C_NO_CREDENTIAL;
+    gss_cred_id_t delegated_cred_handle = GSS_C_NO_CREDENTIAL;
+    gss_name_t user = GSS_C_NO_NAME, target = GSS_C_NO_NAME;
+    gss_OID_set_desc mechs;
+    gss_OID_set actual_mechs = GSS_C_NO_OID_SET;
+    gss_buffer_desc buf;
+
+    if (argc < 2 || argc > 5) {
+        fprintf(stderr, "Usage: %s [--spnego] [user] "
+                        "[proxy-target] [keytab]\n", argv[0]);
+        fprintf(stderr, "       proxy-target and keytab are optional\n");
+        exit(1);
+    }
+
+    if (strcmp(argv[1], "--spnego") == 0) {
+        use_spnego++;
+        argc--;
+        argv++;
+    }
+
+    buf.value = argv[1];
+    buf.length = strlen((char *)buf.value);
+
+    major = gss_import_name(&minor, &buf,
+                            (gss_OID)GSS_KRB5_NT_PRINCIPAL_NAME,
+                            &user);
+    if (GSS_ERROR(major)) {
+        displayStatus("gss_import_name(user)", major, minor);
+        goto out;
+    }
+
+    if (argc > 2 && strcmp(argv[2], "-")) {
+        buf.value = argv[2];
+        buf.length = strlen((char *)buf.value);
+
+        major = gss_import_name(&minor, &buf,
+                                (gss_OID)GSS_KRB5_NT_PRINCIPAL_NAME,
+                                &target);
+        if (GSS_ERROR(major)) {
+            displayStatus("gss_import_name(target)", major, minor);
+            goto out;
+        }
+    } else {
+        target = GSS_C_NO_NAME;
+    }
+
+    if (argc > 3) {
+        major = krb5_gss_register_acceptor_identity(argv[3]);
+        if (GSS_ERROR(major)) {
+            displayStatus("krb5_gss_register_acceptor_identity",
+                          major, minor);
+            goto out;
+        }
+    }
+
+    mechs.elements = use_spnego ? (gss_OID)&spnego_mech :
+                                  (gss_OID)gss_mech_krb5;
+    mechs.count = 1;
+
+    /* get default cred */
+    major = gss_acquire_cred(&minor,
+                             GSS_C_NO_NAME,
+                             GSS_C_INDEFINITE,
+                             &mechs,
+                             GSS_C_BOTH,
+                             &impersonator_cred_handle,
+                             &actual_mechs,
+                             NULL);
+    if (GSS_ERROR(major)) {
+        displayStatus("gss_acquire_cred", major, minor);
+        goto out;
+    }
+
+    (void) gss_release_oid_set(&minor, &actual_mechs);
+
+    printf("Protocol transition tests follow\n");
+    printf("-----------------------------------\n\n");
+
+    /* get S4U2Self cred */
+    major = gss_acquire_cred_impersonate_name(&minor,
+                                              impersonator_cred_handle,
+                                              user,
+                                              GSS_C_INDEFINITE,
+                                              &mechs,
+                                              GSS_C_INITIATE,
+                                              &user_cred_handle,
+                                              &actual_mechs,
+                                              NULL);
+    if (GSS_ERROR(major)) {
+        displayStatus("gss_acquire_cred_impersonate_name", major, minor);
+        goto out;
+    }
+
+    major = initAcceptSecContext(&minor,
+                                 user_cred_handle,
+                                 impersonator_cred_handle,
+                                 &delegated_cred_handle);
+    if (GSS_ERROR(major))
+        goto out;
+
+    printf("\n");
+
+    if (target != GSS_C_NO_NAME &&
+        delegated_cred_handle != GSS_C_NO_CREDENTIAL) {
+        major = constrainedDelegate(&minor, &mechs, target,
+                                    delegated_cred_handle,
+                                    impersonator_cred_handle);
+    } else if (target != GSS_C_NO_NAME) {
+        fprintf(stderr, "Warning: no delegated credentials handle returned\n\n");
+        fprintf(stderr, "Verify:\n\n");
+        fprintf(stderr, " - The TGT for the impersonating service is forwardable\n");
+        fprintf(stderr, " - The T2A4D flag set on the impersonating service's UAC\n");
+        fprintf(stderr, " - The user is not marked sensitive and cannot be delegated\n");
+        fprintf(stderr, "\n");
+    }
+
+out:
+    (void) gss_release_name(&minor, &user);
+    (void) gss_release_name(&minor, &target);
+    (void) gss_release_cred(&minor, &delegated_cred_handle);
+    (void) gss_release_cred(&minor, &impersonator_cred_handle);
+    (void) gss_release_cred(&minor, &user_cred_handle);
+    (void) gss_release_oid_set(&minor, &actual_mechs);
+
+    return GSS_ERROR(major) ? 1 : 0;
+}
+