2 * Hashed Message Authentication Code using MD5 (HMAC-MD5)
4 * hmac_md5 was based on sample code in RFC2104 (thanks guys).
6 * Adapted to Bacula by Kern E. Sibbald, February MMI.
11 Copyright (C) 2000-2004 Kern Sibbald and John Walker
13 This library is free software; you can redistribute it and/or
14 modify it under the terms of the GNU Lesser General Public
15 License as published by the Free Software Foundation; either
16 version 2.1 of the License, or (at your option) any later version.
18 This library is distributed in the hope that it will be useful,
19 but WITHOUT ANY WARRANTY; without even the implied warranty of
20 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
21 Lesser General Public License for more details.
23 You should have received a copy of the GNU Lesser General Public
24 License along with this library; if not, write to the Free
25 Software Foundation, Inc., 59 Temple Place, Suite 330, Boston,
32 #define PAD_LEN 64 /* PAD length */
33 #define SIG_LEN MD5HashSize /* MD5 digest length */
37 uint8_t* text, /* pointer to data stream */
38 int text_len, /* length of data stream */
39 uint8_t* key, /* pointer to authentication key */
40 int key_len, /* length of authentication key */
41 uint8_t *hmac) /* returned hmac-md5 */
44 uint8_t k_ipad[PAD_LEN]; /* inner padding - key XORd with ipad */
45 uint8_t k_opad[PAD_LEN]; /* outer padding - key XORd with opad */
46 uint8_t keysig[SIG_LEN];
49 /* if key is longer than PAD length, reset it to key=MD5(key) */
50 if (key_len > PAD_LEN) {
54 MD5Update(&md5key, key, key_len);
55 MD5Final(keysig, &md5key);
62 * the HMAC_MD5 transform looks like:
64 * MD5(Key XOR opad, MD5(Key XOR ipad, text))
66 * where Key is an n byte key
67 * ipad is the byte 0x36 repeated 64 times
69 * opad is the byte 0x5c repeated 64 times
70 * and text is the data being protected
73 /* Zero pads and store key */
74 memset(k_ipad, 0, PAD_LEN);
75 memcpy(k_ipad, key, key_len);
76 memcpy(k_opad, k_ipad, PAD_LEN);
78 /* XOR key with ipad and opad values */
79 for (i=0; i<PAD_LEN; i++) {
84 /* perform inner MD5 */
85 MD5Init(&md5c); /* start inner hash */
86 MD5Update(&md5c, k_ipad, PAD_LEN); /* hash inner pad */
87 MD5Update(&md5c, text, text_len); /* hash text */
88 MD5Final(hmac, &md5c); /* store inner hash */
90 /* perform outer MD5 */
91 MD5Init(&md5c); /* start outer hash */
92 MD5Update(&md5c, k_opad, PAD_LEN); /* hash outer pad */
93 MD5Update(&md5c, hmac, SIG_LEN); /* hash inner hash */
94 MD5Final(hmac, &md5c); /* store results */
97 Test Vectors (Trailing '\0' of a character string not included in test):
99 key = 0x0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b0b
103 digest = 0x9294727a3638bb1c13f48ef8158bfc9d
106 data = "what do ya want for nothing?"
108 digest = 0x750c783e6ab0b503eaa86e310a5db738
110 key = 0xAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA
113 data = 0xDDDDDDDDDDDDDDDDDDDD...
114 ..DDDDDDDDDDDDDDDDDDDD...
115 ..DDDDDDDDDDDDDDDDDDDD...
116 ..DDDDDDDDDDDDDDDDDDDD...
117 ..DDDDDDDDDDDDDDDDDDDD
119 digest = 0x56be34521d144c88dbb8c733f0e8b3f6