1 files changed, 120 insertions, 0 deletions
diff --git a/crammd5/hmacmd5.c b/crammd5/hmacmd5.c
new file mode 100644
index 0000000..80e2b33
--- /dev/null
+++ b/crammd5/hmacmd5.c
@@ -0,0 +1,120 @@
+/*
+ *  This file is part of libESMTP, a library for submission of RFC 2822
+ *  formatted electronic mail messages using the SMTP protocol described
+ *  in RFC 2821.
+ *
+ *  Copyright (C) 2001,2002  Brian Stafford  <brian@stafford.uklinux.net>
+ *
+ *  This library is free software; you can redistribute it and/or
+ *  modify it under the terms of the GNU Lesser General Public
+ *  License as published by the Free Software Foundation; either
+ *  version 2.1 of the License, or (at your option) any later version.
+ *
+ *  This library is distributed in the hope that it will be useful,
+ *  but WITHOUT ANY WARRANTY; without even the implied warranty of
+ *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ *  Lesser General Public License for more details.
+ *
+ *  You should have received a copy of the GNU Lesser General Public
+ *  License along with this library; if not, write to the Free Software
+ *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
+ */
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#include <string.h>
+#include <sys/types.h>
+#include "hmacmd5.h"
+
+#define PAD_SIZE	64
+
+/*
+ * the HMAC_MD5 transform looks like:
+ *
+ * MD5(K XOR opad, MD5(K XOR ipad, challenge))
+ *
+ * where K is an n byte secret
+ * ipad is the byte 0x36 repeated 64 times
+ * opad is the byte 0x5c repeated 64 times
+ * and challenge is the data being protected
+ */
+
+/* Precompute HMAC-MD5 contexts from a secret
+ */
+void
+hmac_md5_pre (const void *secret, size_t secret_len,
+              MD5_CTX *inner, MD5_CTX *outer)
+{
+  unsigned char ipad[PAD_SIZE];
+  unsigned char opad[PAD_SIZE];
+  unsigned char tk[16];
+  int i;
+
+  /* If secret is longer than 64 bytes reset it to secret = MD5 (secret)
+   */
+  if (secret_len > PAD_SIZE)
+    {
+      MD5_CTX tctx;
+
+      MD5_Init (&tctx);
+      MD5_Update (&tctx, secret, secret_len);
+      MD5_Final (tk, &tctx);
+      secret = tk;
+      secret_len = sizeof tk;
+    }
+
+  /* start out by storing secret in pads */
+  memcpy (ipad, secret, secret_len);
+  if (secret_len < sizeof ipad)
+    memset (ipad + secret_len, 0, sizeof ipad - secret_len);
+  memcpy (opad, secret, secret_len);
+  if (secret_len < sizeof opad)
+    memset (opad + secret_len, 0, sizeof opad - secret_len);
+
+  /* XOR secret with ipad and opad values */
+  for (i = 0; i < PAD_SIZE; i++)
+    {
+      ipad[i] ^= 0x36;
+      opad[i] ^= 0x5c;
+    }
+
+  /* perform inner MD5 */
+  MD5_Init (inner);
+  MD5_Update (inner, ipad, sizeof ipad);
+
+  /* perform outer MD5 */
+  MD5_Init (outer);
+  MD5_Update (outer, opad, sizeof opad);
+}
+
+/* Finalise HMAC-MD5 contexts from a challenge
+ */
+void
+hmac_md5_post (const void *challenge, size_t challenge_len,
+               MD5_CTX *inner, MD5_CTX *outer, unsigned char digest[16])
+{
+  unsigned char id[16];
+
+  /* perform inner MD5 */
+  MD5_Update (inner, challenge, challenge_len);
+  MD5_Final (id, inner);
+
+  /* perform outer MD5 */
+  MD5_Update (outer, id, sizeof id);
+  MD5_Final (digest, outer);
+}
+
+/* Digest a challenge and a secret.
+ */
+void
+hmac_md5 (const void *challenge, size_t challenge_len,
+	  const void *secret, size_t secret_len,
+	  unsigned char digest[16])
+{
+  MD5_CTX inner, outer;
+
+  hmac_md5_pre (secret, secret_len, &inner, &outer);
+  hmac_md5_post (challenge, challenge_len, &inner, &outer, digest);
+}
+