85 lines
2.5 KiB
C
85 lines
2.5 KiB
C
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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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* Tom St Denis, tomstdenis@iahu.ca, http://libtomcrypt.org
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*/
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/* Submited by Dobes Vandermeer (dobes@smartt.com) */
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#include "mycrypt.h"
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/*
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(1) append zeros to the end of K to create a B byte string
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(e.g., if K is of length 20 bytes and B=64, then K will be
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appended with 44 zero bytes 0x00)
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(2) XOR (bitwise exclusive-OR) the B byte string computed in step
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(1) with ipad (ipad = the byte 0x36 repeated B times)
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(3) append the stream of data 'text' to the B byte string resulting
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from step (2)
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(4) apply H to the stream generated in step (3)
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(5) XOR (bitwise exclusive-OR) the B byte string computed in
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step (1) with opad (opad = the byte 0x5C repeated B times.)
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(6) append the H result from step (4) to the B byte string
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resulting from step (5)
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(7) apply H to the stream generated in step (6) and output
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the result
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*/
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#ifdef HMAC
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#define HMAC_BLOCKSIZE hash_descriptor[hash].blocksize
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int hmac_done(hmac_state *hmac, unsigned char *hashOut, unsigned long *outlen)
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{
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unsigned char buf[MAXBLOCKSIZE];
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unsigned char isha[MAXBLOCKSIZE];
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unsigned long hashsize, i;
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int hash, err;
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_ARGCHK(hmac != NULL);
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_ARGCHK(hashOut != NULL);
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hash = hmac->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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/* get the hash message digest size */
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hashsize = hash_descriptor[hash].hashsize;
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// Get the hash of the first HMAC vector plus the data
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if ((err = hash_descriptor[hash].done(&hmac->md, isha)) != CRYPT_OK) {
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return err;
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}
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// Create the second HMAC vector vector for step (3)
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for(i=0; i < HMAC_BLOCKSIZE; i++) {
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buf[i] = hmac->key[i] ^ 0x5C;
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}
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// Now calculate the "outer" hash for step (5), (6), and (7)
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hash_descriptor[hash].init(&hmac->md);
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hash_descriptor[hash].process(&hmac->md, buf, HMAC_BLOCKSIZE);
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hash_descriptor[hash].process(&hmac->md, isha, hashsize);
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hash_descriptor[hash].done(&hmac->md, buf);
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// copy to output
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for (i = 0; i < hashsize && i < *outlen; i++) {
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hashOut[i] = buf[i];
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}
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*outlen = i;
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#ifdef CLEAN_STACK
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zeromem(isha, sizeof(buf));
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zeromem(buf, sizeof(isha));
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zeromem(hmac, sizeof(*hmac));
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#endif
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return CRYPT_OK;
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}
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#endif
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