Mercurial > dropbear
view libtomcrypt/src/mac/hmac/hmac_init.c @ 397:2908122e9eed channel-fix
disapproval of revision '1250b8af44b62d8f4fe0f8d9fc7e7a1cc34e7e1c'
author | Matt Johnston <matt@ucc.asn.au> |
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date | Sat, 03 Feb 2007 08:10:09 +0000 |
parents | 1b9e69c058d2 |
children | 0cbe8f6dbf9e |
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/* 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, [email protected], http://libtomcrypt.org */ #include "tomcrypt.h" /** @file hmac_init.c HMAC support, initialize state, Tom St Denis/Dobes Vandermeer */ #ifdef 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: 1.3 $ */ /* $Date: 2005/05/05 14:35:58 $ */