1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
|
#include "k5-int.h"
#include "rsa-md5.h"
#include "des_int.h" /* we cheat a bit and call it directly... */
/* Windows needs to these prototypes for the assignment below */
krb5_error_code
krb5_md5_crypto_sum_func PROTOTYPE((krb5_pointer in, size_t in_length,
krb5_pointer seed, size_t seed_length, krb5_checksum FAR *outcksum));
krb5_error_code
krb5_md5_crypto_verify_func PROTOTYPE((krb5_checksum FAR *cksum, krb5_pointer in,
size_t in_length, krb5_pointer seed, size_t seed_length));
static mit_des_cblock zero_ivec = { 0 };
/*
* In Kerberos V5 Beta 5 and previous releases the RSA-MD5-DES implementation
* did not follow RFC1510. The folowing definitions control the compatibility
* with these releases.
*
* If MD5_K5BETA_COMPAT is defined, then compatability mode is enabled. That
* means that both checksum functions are compiled and available for use and
* the additional interface krb5_md5_crypto_compat_ctl() is defined.
*
* If MD5_K5BETA_COMPAT_DEF is defined and compatability mode is enabled, then
* the compatible behaviour becomes the default.
*
*/
#define MD5_K5BETA_COMPAT
#define MD5_K5BETA_COMPAT_DEF
static void
krb5_md5_calculate_cksum(md5ctx, confound, confound_length, in, in_length)
krb5_MD5_CTX *md5ctx;
krb5_pointer in;
size_t in_length;
krb5_pointer confound;
size_t confound_length;
{
krb5_MD5Init(md5ctx);
if (confound && confound_length)
krb5_MD5Update(md5ctx, confound, confound_length);
krb5_MD5Update(md5ctx, in, in_length);
krb5_MD5Final(md5ctx);
}
#ifdef MD5_K5BETA_COMPAT
krb5_error_code
krb5_md5_crypto_compat_sum_func(in, in_length, seed, seed_length, outcksum)
krb5_pointer in;
size_t in_length;
krb5_pointer seed;
size_t seed_length;
krb5_checksum FAR *outcksum;
{
krb5_octet outtmp[OLD_RSA_MD5_DES_CKSUM_LENGTH];
krb5_octet *input = (krb5_octet *)in;
krb5_encrypt_block eblock;
krb5_keyblock keyblock;
krb5_error_code retval;
krb5_MD5_CTX working;
krb5_MD5Init(&working);
krb5_MD5Update(&working, input, in_length);
krb5_MD5Final(&working);
outcksum->checksum_type = CKSUMTYPE_RSA_MD5_DES;
outcksum->length = OLD_RSA_MD5_DES_CKSUM_LENGTH;
memcpy((char *)outtmp, (char *)&working.digest[0], 16);
memset((char *)&working, 0, sizeof(working));
keyblock.length = seed_length;
keyblock.contents = (krb5_octet *)seed;
keyblock.enctype = ENCTYPE_DES_CBC_MD5;
if ((retval = mit_des_process_key(&eblock, &keyblock)))
return retval;
/* now encrypt it */
retval = mit_des_cbc_encrypt((mit_des_cblock *)&outtmp[0],
(mit_des_cblock *)outcksum->contents,
OLD_RSA_MD5_DES_CKSUM_LENGTH,
(struct mit_des_ks_struct *)eblock.priv,
keyblock.contents,
MIT_DES_ENCRYPT);
if (retval) {
(void) mit_des_finish_key(&eblock);
return retval;
}
return mit_des_finish_key(&eblock);
}
#endif /* MD5_K5BETA_COMPAT */
krb5_error_code
krb5_md5_crypto_sum_func(in, in_length, seed, seed_length, outcksum)
krb5_pointer in;
size_t in_length;
krb5_pointer seed;
size_t seed_length;
krb5_checksum FAR *outcksum;
{
krb5_octet outtmp[NEW_RSA_MD5_DES_CKSUM_LENGTH];
mit_des_cblock tmpkey;
krb5_encrypt_block eblock;
krb5_keyblock keyblock;
krb5_error_code retval;
size_t i;
krb5_MD5_CTX working;
if (outcksum->length < NEW_RSA_MD5_DES_CKSUM_LENGTH)
return KRB5_BAD_MSIZE;
/* Generate the confounder in place */
if ((retval = krb5_random_confounder(RSA_MD5_DES_CONFOUND_LENGTH, outtmp)))
return(retval);
/* Calculate the checksum */
krb5_md5_calculate_cksum(&working,
(krb5_pointer) outtmp,
(size_t) RSA_MD5_DES_CONFOUND_LENGTH,
in,
in_length);
outcksum->checksum_type = CKSUMTYPE_RSA_MD5_DES;
outcksum->length = NEW_RSA_MD5_DES_CKSUM_LENGTH;
/* Now blast in the digest */
memcpy((char *)&outtmp[RSA_MD5_DES_CONFOUND_LENGTH],
(char *)&working.digest[0],
RSA_MD5_CKSUM_LENGTH);
/* Clean up the droppings */
memset((char *)&working, 0, sizeof(working));
/* Set up the temporary copy of the key (see RFC 1510 section 6.4.5) */
memset((char *) tmpkey, 0, sizeof(mit_des_cblock));
for (i=0; (i<seed_length) && (i<sizeof(mit_des_cblock)); i++)
tmpkey[i] = (((krb5_octet *) seed)[i]) ^ 0xf0;
keyblock.length = sizeof(mit_des_cblock);
keyblock.contents = (krb5_octet *) tmpkey;
keyblock.enctype = ENCTYPE_DES_CBC_MD5;
if ((retval = mit_des_process_key(&eblock, &keyblock)))
return retval;
/* now encrypt it */
retval = mit_des_cbc_encrypt((mit_des_cblock *)&outtmp[0],
(mit_des_cblock *)outcksum->contents,
NEW_RSA_MD5_DES_CKSUM_LENGTH,
(struct mit_des_ks_struct *)eblock.priv,
zero_ivec,
MIT_DES_ENCRYPT);
if (retval) {
(void) mit_des_finish_key(&eblock);
return retval;
}
return mit_des_finish_key(&eblock);
}
krb5_error_code
krb5_md5_crypto_verify_func(cksum, in, in_length, seed, seed_length)
krb5_checksum FAR *cksum;
krb5_pointer in;
size_t in_length;
krb5_pointer seed;
size_t seed_length;
{
krb5_octet outtmp[NEW_RSA_MD5_DES_CKSUM_LENGTH];
mit_des_cblock tmpkey;
krb5_encrypt_block eblock;
krb5_keyblock keyblock;
krb5_error_code retval;
size_t i;
krb5_MD5_CTX working;
retval = 0;
if (cksum->checksum_type == CKSUMTYPE_RSA_MD5_DES) {
#ifdef MD5_K5BETA_COMPAT
/*
* We have a backwards compatibility problem here. Kerberos
* version 5 Beta 5 and previous releases did not correctly
* generate RSA-MD5-DES checksums. The way that we can
* differentiate is by the length of the provided checksum.
* If it's only OLD_RSA_MD5_DES_CKSUM_LENGTH, then it's the
* old style, otherwise it's the correct implementation.
*/
if (cksum->length == OLD_RSA_MD5_DES_CKSUM_LENGTH) {
/*
* If we're verifying the Old Style (tm) checksum, then we can just
* recalculate the checksum and encrypt it and see if it's the
* same.
*/
/* Recalculate the checksum with no confounder */
krb5_md5_calculate_cksum(&working,
(krb5_pointer) NULL,
(size_t) 0,
in,
in_length);
/* Use the key "as-is" */
keyblock.length = seed_length;
keyblock.contents = (krb5_octet *) seed;
keyblock.enctype = ENCTYPE_DES_CBC_MD5;
if ((retval = mit_des_process_key(&eblock, &keyblock)))
return retval;
/* now encrypt the checksum */
retval = mit_des_cbc_encrypt((mit_des_cblock *)&working.digest[0],
(mit_des_cblock *)&outtmp[0],
OLD_RSA_MD5_DES_CKSUM_LENGTH,
(struct mit_des_ks_struct *)
eblock.priv,
keyblock.contents,
MIT_DES_ENCRYPT);
if (retval) {
(void) mit_des_finish_key(&eblock);
return retval;
}
if ((retval = mit_des_finish_key(&eblock)))
return(retval);
/* Compare the encrypted checksums */
if (memcmp((char *) &outtmp[0],
(char *) cksum->contents,
OLD_RSA_MD5_DES_CKSUM_LENGTH))
retval = KRB5KRB_AP_ERR_BAD_INTEGRITY;
}
else
#endif /* MD5_K5BETA_COMPAT */
if (cksum->length == (NEW_RSA_MD5_DES_CKSUM_LENGTH)) {
/*
* If we're verifying the correct implementation, then we have
* to do a little more work because we must decrypt the checksum
* because it contains the confounder in it. So, figure out
* what our key variant is and then do it!
*/
/* Set up the variant of the key (see RFC 1510 section 6.4.5) */
memset((char *) tmpkey, 0, sizeof(mit_des_cblock));
for (i=0; (i<seed_length) && (i<sizeof(mit_des_cblock)); i++)
tmpkey[i] = (((krb5_octet *) seed)[i]) ^ 0xf0;
keyblock.length = sizeof(mit_des_cblock);
keyblock.contents = (krb5_octet *) tmpkey;
keyblock.enctype = ENCTYPE_DES_CBC_MD5;
if ((retval = mit_des_process_key(&eblock, &keyblock)))
return retval;
/* now decrypt it */
retval = mit_des_cbc_encrypt((mit_des_cblock *)cksum->contents,
(mit_des_cblock *)&outtmp[0],
NEW_RSA_MD5_DES_CKSUM_LENGTH,
(struct mit_des_ks_struct *)
eblock.priv,
zero_ivec,
MIT_DES_DECRYPT);
if (retval) {
(void) mit_des_finish_key(&eblock);
return retval;
}
if ((retval = mit_des_finish_key(&eblock)))
return(retval);
/* Now that we have the decrypted checksum, try to regenerate it */
krb5_md5_calculate_cksum(&working,
(krb5_pointer) outtmp,
(size_t) RSA_MD5_DES_CONFOUND_LENGTH,
in,
in_length);
/* Compare the checksums */
if (memcmp((char *) &outtmp[RSA_MD5_DES_CONFOUND_LENGTH],
(char *) &working.digest[0],
RSA_MD5_CKSUM_LENGTH))
retval = KRB5KRB_AP_ERR_BAD_INTEGRITY;
}
else
retval = KRB5KRB_AP_ERR_BAD_INTEGRITY;
}
else
retval = KRB5KRB_AP_ERR_INAPP_CKSUM;
/* Clean up droppings */
memset((char *)&working, 0, sizeof(working));
return(retval);
}
krb5_checksum_entry rsa_md5_des_cksumtable_entry =
#if defined(MD5_K5BETA_COMPAT) && defined(MD5_K5BETA_COMPAT_DEF)
{
0,
krb5_md5_crypto_compat_sum_func,
krb5_md5_crypto_verify_func,
OLD_RSA_MD5_DES_CKSUM_LENGTH,
1, /* is collision proof */
1, /* uses key */
};
#else /* MD5_K5BETA_COMPAT && MD5_K5BETA_COMPAT_DEF */
{
0,
krb5_md5_crypto_sum_func,
krb5_md5_crypto_verify_func,
NEW_RSA_MD5_DES_CKSUM_LENGTH,
1, /* is collision proof */
1, /* uses key */
};
#endif /* MD5_K5BETA_COMPAT && MD5_K5BETA_COMPAT_DEF */
#ifdef MD5_K5BETA_COMPAT
/*
* Turn on/off compatible checksum generation.
*/
void
krb5_md5_crypto_compat_ctl(scompat)
krb5_boolean scompat;
{
if (scompat) {
rsa_md5_des_cksumtable_entry.sum_func = krb5_md5_crypto_compat_sum_func;
rsa_md5_des_cksumtable_entry.checksum_length =
OLD_RSA_MD5_DES_CKSUM_LENGTH;
}
else {
rsa_md5_des_cksumtable_entry.sum_func = krb5_md5_crypto_sum_func;
rsa_md5_des_cksumtable_entry.checksum_length =
NEW_RSA_MD5_DES_CKSUM_LENGTH;
}
}
#endif /* MD5_K5BETA_COMPAT */
|
