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102 lines
2.5 KiB
102 lines
2.5 KiB
#define LTC_SOURCE
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/* LibTomCrypt, modular cryptographic library -- Tom St Denis
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*
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* LibTomCrypt is a library that provides various cryptographic
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* algorithms in a highly modular and flexible manner.
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*
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* The library is free for all purposes without any express
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* guarantee it works.
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*/
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#include "tomcrypt.h"
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/**
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@file hmac_init.c
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HMAC support, initialize state, Tom St Denis/Dobes Vandermeer
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*/
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#ifdef LTC_HMAC
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#define LTC_HMAC_BLOCKSIZE hash_descriptor[hash].blocksize
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/**
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Initialize an HMAC context.
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@param hmac The HMAC state
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@param hash The index of the hash you want to use
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@param key The secret key
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@param keylen The length of the secret key (octets)
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@return CRYPT_OK if successful
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*/
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int hmac_init(hmac_state *hmac, int hash, const unsigned char *key, unsigned long keylen)
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{
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unsigned char buf[MAXBLOCKSIZE];
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unsigned long hashsize;
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unsigned long i, z;
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int err;
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LTC_ARGCHK(hmac != NULL);
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LTC_ARGCHK(key != NULL);
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/* valid hash? */
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if ((err = hash_is_valid(hash)) != CRYPT_OK) {
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return err;
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}
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hmac->hash = hash;
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hashsize = hash_descriptor[hash].hashsize;
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/* valid key length? */
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if (keylen == 0) {
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return CRYPT_INVALID_KEYSIZE;
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}
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/* allocate memory for key */
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hmac->key = XMALLOC(LTC_HMAC_BLOCKSIZE);
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if (hmac->key == NULL) {
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return CRYPT_MEM;
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}
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/* (1) make sure we have a large enough key */
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if(keylen > LTC_HMAC_BLOCKSIZE) {
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z = LTC_HMAC_BLOCKSIZE;
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if ((err = hash_memory(hash, key, keylen, hmac->key, &z)) != CRYPT_OK) {
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goto LBL_ERR;
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}
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keylen = hashsize;
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} else {
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XMEMCPY(hmac->key, key, (size_t)keylen);
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}
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if(keylen < LTC_HMAC_BLOCKSIZE) {
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zeromem((hmac->key) + keylen, (size_t)(LTC_HMAC_BLOCKSIZE - keylen));
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}
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/* Create the initialization vector for step (3) */
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for(i=0; i < LTC_HMAC_BLOCKSIZE; i++) {
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buf[i] = hmac->key[i] ^ 0x36;
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}
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/* Pre-pend that to the hash data */
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if ((err = hash_descriptor[hash].init(&hmac->md)) != CRYPT_OK) {
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goto LBL_ERR;
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}
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if ((err = hash_descriptor[hash].process(&hmac->md, buf, LTC_HMAC_BLOCKSIZE)) != CRYPT_OK) {
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goto LBL_ERR;
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}
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goto done;
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LBL_ERR:
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/* free the key since we failed */
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XFREE(hmac->key);
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done:
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#ifdef LTC_CLEAN_STACK
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zeromem(buf, LTC_HMAC_BLOCKSIZE);
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#endif
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return err;
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}
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#endif
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/* ref: $Format:%D$ */
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/* git commit: $Format:%H$ */
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/* commit time: $Format:%ai$ */
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