| /* LibTomCrypt, modular cryptographic library -- Tom St Denis |
| * |
| * LibTomCrypt is a library that provides various cryptographic |
| * algorithms in a highly modular and flexible manner. |
| * |
| * The library is free for all purposes without any express |
| * guarantee it works. |
| * |
| * Tom St Denis, tomstdenis@gmail.com, http://libtomcrypt.com |
| */ |
| #include "tomcrypt.h" |
| |
| /** |
| @file hmac_init.c |
| HMAC support, initialize state, Tom St Denis/Dobes Vandermeer |
| */ |
| |
| #ifdef LTC_HMAC |
| |
| #define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize |
| |
| /** |
| Initialize an HMAC context. |
| @param hmac The HMAC state |
| @param hash The index of the hash you want to use |
| @param key The secret key |
| @param keylen The length of the secret key (octets) |
| @return CRYPT_OK if successful |
| */ |
| int hmac_init(hmac_state *hmac, int hash, const unsigned char *key, unsigned long keylen) |
| { |
| unsigned char *buf; |
| unsigned long hashsize; |
| unsigned long i, z; |
| int err; |
| |
| LTC_ARGCHK(hmac != NULL); |
| LTC_ARGCHK(key != NULL); |
| |
| /* valid hash? */ |
| if ((err = hash_is_valid(hash)) != CRYPT_OK) { |
| return err; |
| } |
| hmac->hash = hash; |
| hashsize = hash_descriptor[hash].hashsize; |
| |
| /* valid key length? */ |
| if (keylen == 0) { |
| return CRYPT_INVALID_KEYSIZE; |
| } |
| |
| /* allocate ram for buf */ |
| buf = XMALLOC(HMAC_BLOCKSIZE); |
| if (buf == NULL) { |
| return CRYPT_MEM; |
| } |
| |
| /* allocate memory for key */ |
| hmac->key = XMALLOC(HMAC_BLOCKSIZE); |
| if (hmac->key == NULL) { |
| XFREE(buf); |
| return CRYPT_MEM; |
| } |
| |
| /* (1) make sure we have a large enough key */ |
| if(keylen > HMAC_BLOCKSIZE) { |
| z = HMAC_BLOCKSIZE; |
| if ((err = hash_memory(hash, key, keylen, hmac->key, &z)) != CRYPT_OK) { |
| goto LBL_ERR; |
| } |
| if(hashsize < HMAC_BLOCKSIZE) { |
| zeromem((hmac->key) + hashsize, (size_t)(HMAC_BLOCKSIZE - hashsize)); |
| } |
| keylen = hashsize; |
| } else { |
| XMEMCPY(hmac->key, key, (size_t)keylen); |
| if(keylen < HMAC_BLOCKSIZE) { |
| zeromem((hmac->key) + keylen, (size_t)(HMAC_BLOCKSIZE - keylen)); |
| } |
| } |
| |
| /* Create the initial vector for step (3) */ |
| for(i=0; i < HMAC_BLOCKSIZE; i++) { |
| buf[i] = hmac->key[i] ^ 0x36; |
| } |
| |
| /* Pre-pend that to the hash data */ |
| if ((err = hash_descriptor[hash].init(&hmac->md)) != CRYPT_OK) { |
| goto LBL_ERR; |
| } |
| |
| if ((err = hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE)) != CRYPT_OK) { |
| goto LBL_ERR; |
| } |
| goto done; |
| LBL_ERR: |
| /* free the key since we failed */ |
| XFREE(hmac->key); |
| done: |
| #ifdef LTC_CLEAN_STACK |
| zeromem(buf, HMAC_BLOCKSIZE); |
| #endif |
| |
| XFREE(buf); |
| return err; |
| } |
| |
| #endif |
| |
| /* $Source: /cvs/libtom/libtomcrypt/src/mac/hmac/hmac_init.c,v $ */ |
| /* $Revision: 1.5 $ */ |
| /* $Date: 2006/11/03 00:39:49 $ */ |