| /* 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[MAXBLOCKSIZE]; |
| unsigned long hashsize; |
| unsigned long i, z; |
| int err; |
| |
| _ARGCHK(hmac != NULL); |
| _ARGCHK(key != NULL); |
| |
| if ((err = hash_is_valid(hash)) != CRYPT_OK) { |
| return err; |
| } |
| |
| /* valid key length? */ |
| if (keylen == 0) { |
| return CRYPT_INVALID_KEYSIZE; |
| } |
| |
| hmac->hash = hash; |
| |
| // (1) make sure we have a large enough key |
| hashsize = hash_descriptor[hash].hashsize; |
| if(keylen > HMAC_BLOCKSIZE) { |
| z = (unsigned long)sizeof(hmac->key); |
| if ((err = hash_memory(hash, key, keylen, hmac->key, &z)) != CRYPT_OK) { |
| return err; |
| } |
| if(hashsize < HMAC_BLOCKSIZE) { |
| zeromem((hmac->key) + hashsize, (size_t)(HMAC_BLOCKSIZE - hashsize)); |
| } |
| keylen = hashsize; |
| } else { |
| memcpy(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 |
| hash_descriptor[hash].init(&hmac->md); |
| hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE); |
| |
| return CRYPT_OK; |
| } |
| |
| #endif |