97 lines
2.5 KiB
C
97 lines
2.5 KiB
C
/* 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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/* hmac_file added by Tom St Denis */
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int hmac_file(int hash, const char *fname,
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const unsigned char *key, unsigned long keylen,
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unsigned char *dst, unsigned long *dstlen)
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{
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#ifdef NO_FILE
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return CRYPT_NOP;
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#else
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hmac_state hmac;
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FILE *in;
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unsigned char buf[512];
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size_t x;
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int err;
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_ARGCHK(fname != NULL);
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_ARGCHK(key != NULL);
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_ARGCHK(dst != NULL);
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_ARGCHK(dstlen != NULL);
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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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if ((err = hmac_init(&hmac, hash, key, keylen)) != CRYPT_OK) {
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return err;
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}
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in = fopen(fname, "rb");
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if (in == NULL) {
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return CRYPT_FILE_NOTFOUND;
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}
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/* process the file contents */
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do {
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x = fread(buf, 1, sizeof(buf), in);
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if ((err = hmac_process(&hmac, buf, (unsigned long)x)) != CRYPT_OK) {
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/* we don't trap this error since we're already returning an error! */
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fclose(in);
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return err;
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}
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} while (x == sizeof(buf));
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if (fclose(in) != 0) {
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return CRYPT_ERROR;
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}
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/* get final hmac */
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if ((err = hmac_done(&hmac, dst, dstlen)) != CRYPT_OK) {
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return err;
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}
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#ifdef CLEAN_STACK
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/* clear memory */
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zeromem(buf, sizeof(buf));
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#endif
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return CRYPT_OK;
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#endif
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}
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#endif
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