From bed930fd70742af5ae138e0a5ee629dda296ea36 Mon Sep 17 00:00:00 2001 From: Josh Bailey Date: Wed, 21 Mar 2012 10:22:19 -0700 Subject: lib: add support for keyed-hashing with MD5 * lib/md5.[ch] Add implementation of HMAC-MD5 from RFC 2104. From: Josh Bailey Signed-off-by: Avneesh Sachdev Signed-off-by: David Lamparter --- lib/md5.c | 73 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++ lib/md5.h | 4 ++++ 2 files changed, 77 insertions(+) (limited to 'lib') diff --git a/lib/md5.c b/lib/md5.c index 894de648..2fc36e17 100644 --- a/lib/md5.c +++ b/lib/md5.c @@ -298,3 +298,76 @@ static void md5_calc(const uint8_t *b64, md5_ctxt * ctxt) ctxt->md5_stc += C; ctxt->md5_std += D; } + +/* From RFC 2104 */ +void +hmac_md5(text, text_len, key, key_len, digest) +unsigned char* text; /* pointer to data stream */ +int text_len; /* length of data stream */ +unsigned char* key; /* pointer to authentication key */ +int key_len; /* length of authentication key */ +caddr_t digest; /* caller digest to be filled in */ + +{ + MD5_CTX context; + unsigned char k_ipad[65]; /* inner padding - + * key XORd with ipad + */ + unsigned char k_opad[65]; /* outer padding - + * key XORd with opad + */ + unsigned char tk[16]; + int i; + /* if key is longer than 64 bytes reset it to key=MD5(key) */ + if (key_len > 64) { + + MD5_CTX tctx; + + MD5Init(&tctx); + MD5Update(&tctx, key, key_len); + MD5Final(tk, &tctx); + + key = tk; + key_len = 16; + } + + /* + * the HMAC_MD5 transform looks like: + * + * MD5(K XOR opad, MD5(K XOR ipad, text)) + * + * where K is an n byte key + * ipad is the byte 0x36 repeated 64 times + * opad is the byte 0x5c repeated 64 times + * and text is the data being protected + */ + + /* start out by storing key in pads */ + bzero( k_ipad, sizeof k_ipad); + bzero( k_opad, sizeof k_opad); + bcopy( key, k_ipad, key_len); + bcopy( key, k_opad, key_len); + + /* XOR key with ipad and opad values */ + for (i=0; i<64; i++) { + k_ipad[i] ^= 0x36; + k_opad[i] ^= 0x5c; + } + /* + * perform inner MD5 + */ + MD5Init(&context); /* init context for 1st + * pass */ + MD5Update(&context, k_ipad, 64); /* start with inner pad */ + MD5Update(&context, text, text_len); /* then text of datagram */ + MD5Final(digest, &context); /* finish up 1st pass */ + /* + * perform outer MD5 + */ + MD5Init(&context); /* init context for 2nd + * pass */ + MD5Update(&context, k_opad, 64); /* start with outer pad */ + MD5Update(&context, digest, 16); /* then results of 1st + * hash */ + MD5Final(digest, &context); /* finish up 2nd pass */ +} diff --git a/lib/md5.h b/lib/md5.h index 89b9a320..a03bf22a 100644 --- a/lib/md5.h +++ b/lib/md5.h @@ -82,4 +82,8 @@ do { \ md5_result((x), (y)); \ } while (0) +/* From RFC 2104 */ +void hmac_md5(unsigned char* text, int text_len, unsigned char* key, + int key_len, caddr_t digest); + #endif /* ! _LIBZEBRA_MD5_H_*/ -- cgit v1.2.1