| /* 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.org |
| */ |
| #include "tomcrypt.h" |
| |
| /** |
| @file hmac_done.c |
| HMAC support, terminate stream, Tom St Denis/Dobes Vandermeer |
| */ |
| |
| #ifdef HMAC |
| |
| #define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize |
| |
| /** |
| Terminate an HMAC session |
| @param hmac The HMAC state |
| @param out [out] The destination of the HMAC authentication tag |
| @param outlen [in/out] The max size and resulting size of the HMAC authentication tag |
| @return CRYPT_OK if successful |
| */ |
| int hmac_done(hmac_state *hmac, unsigned char *out, unsigned long *outlen) |
| { |
| unsigned char *buf, *isha; |
| unsigned long hashsize, i; |
| int hash, err; |
| |
| LTC_ARGCHK(hmac != NULL); |
| LTC_ARGCHK(out != NULL); |
| |
| /* test hash */ |
| hash = hmac->hash; |
| if((err = hash_is_valid(hash)) != CRYPT_OK) { |
| return err; |
| } |
| |
| /* get the hash message digest size */ |
| hashsize = hash_descriptor[hash].hashsize; |
| |
| /* allocate buffers */ |
| buf = XMALLOC(HMAC_BLOCKSIZE); |
| isha = XMALLOC(hashsize); |
| if (buf == NULL || isha == NULL) { |
| if (buf != NULL) { |
| XFREE(buf); |
| } |
| if (isha != NULL) { |
| XFREE(isha); |
| } |
| return CRYPT_MEM; |
| } |
| |
| /* Get the hash of the first HMAC vector plus the data */ |
| if ((err = hash_descriptor[hash].done(&hmac->md, isha)) != CRYPT_OK) { |
| goto LBL_ERR; |
| } |
| |
| /* Create the second HMAC vector vector for step (3) */ |
| for(i=0; i < HMAC_BLOCKSIZE; i++) { |
| buf[i] = hmac->key[i] ^ 0x5C; |
| } |
| |
| /* Now calculate the "outer" hash for step (5), (6), and (7) */ |
| 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; |
| } |
| if ((err = hash_descriptor[hash].process(&hmac->md, isha, hashsize)) != CRYPT_OK) { |
| goto LBL_ERR; |
| } |
| if ((err = hash_descriptor[hash].done(&hmac->md, buf)) != CRYPT_OK) { |
| goto LBL_ERR; |
| } |
| |
| /* copy to output */ |
| for (i = 0; i < hashsize && i < *outlen; i++) { |
| out[i] = buf[i]; |
| } |
| *outlen = i; |
| |
| err = CRYPT_OK; |
| LBL_ERR: |
| XFREE(hmac->key); |
| #ifdef LTC_CLEAN_STACK |
| zeromem(isha, hashsize); |
| zeromem(buf, hashsize); |
| zeromem(hmac, sizeof(*hmac)); |
| #endif |
| |
| XFREE(isha); |
| XFREE(buf); |
| |
| return err; |
| } |
| |
| #endif |
| |
| /* $Source: /cvs/libtom/libtomcrypt/src/mac/hmac/hmac_done.c,v $ */ |
| /* $Revision: 1.3 $ */ |
| /* $Date: 2005/05/05 14:35:58 $ */ |