blob: 0d894f1345a915ef62013df79bccbd3177c10773 [file] [log] [blame]
/* 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@iahu.ca, http://libtomcrypt.org
*/
/* Submited by Dobes Vandermeer (dobes@smartt.com) */
#include "mycrypt.h"
/*
(1) append zeros to the end of K to create a B byte string
(e.g., if K is of length 20 bytes and B=64, then K will be
appended with 44 zero bytes 0x00)
(2) XOR (bitwise exclusive-OR) the B byte string computed in step
(1) with ipad (ipad = the byte 0x36 repeated B times)
(3) append the stream of data 'text' to the B byte string resulting
from step (2)
(4) apply H to the stream generated in step (3)
(5) XOR (bitwise exclusive-OR) the B byte string computed in
step (1) with opad (opad = the byte 0x5C repeated B times.)
(6) append the H result from step (4) to the B byte string
resulting from step (5)
(7) apply H to the stream generated in step (6) and output
the result
*/
#ifdef HMAC
#define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize
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;
_ARGCHK(hmac != NULL);
_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 __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 __ERR;
}
if ((err = hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE)) != CRYPT_OK) {
goto __ERR;
}
goto done;
__ERR:
/* free the key since we failed */
XFREE(hmac->key);
done:
#ifdef CLEAN_STACK
zeromem(buf, HMAC_BLOCKSIZE);
#endif
XFREE(buf);
return err;
}
#endif