90 lines
2.0 KiB
C
90 lines
2.0 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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#include "mycrypt.h"
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/* The Mask Generation Function (MGF1) for PKCS #1 -- Tom St Denis */
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#ifdef PKCS_1
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int pkcs_1_mgf1(const unsigned char *seed, unsigned long seedlen,
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int hash_idx,
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unsigned char *mask, unsigned long masklen)
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{
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unsigned long hLen, counter, x;
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int err;
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hash_state *md;
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unsigned char *buf;
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_ARGCHK(seed != NULL);
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_ARGCHK(mask != NULL);
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/* ensure valid hash */
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if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {
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return err;
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}
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/* get hash output size */
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hLen = hash_descriptor[hash_idx].hashsize;
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/* allocate memory */
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md = XMALLOC(sizeof(hash_state));
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buf = XMALLOC(hLen);
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if (md == NULL || buf == NULL) {
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if (md != NULL) {
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XFREE(md);
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}
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if (buf != NULL) {
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XFREE(buf);
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}
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return CRYPT_MEM;
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}
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/* start counter */
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counter = 0;
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while (masklen > 0) {
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/* handle counter */
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STORE32H(counter, buf);
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++counter;
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/* get hash of seed || counter */
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hash_descriptor[hash_idx].init(md);
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if ((err = hash_descriptor[hash_idx].process(md, seed, seedlen)) != CRYPT_OK) {
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goto __ERR;
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}
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if ((err = hash_descriptor[hash_idx].process(md, buf, 4)) != CRYPT_OK) {
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goto __ERR;
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}
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if ((err = hash_descriptor[hash_idx].done(md, buf)) != CRYPT_OK) {
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goto __ERR;
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}
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/* store it */
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for (x = 0; x < hLen && masklen > 0; x++, masklen--) {
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*mask++ = buf[x];
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}
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}
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err = CRYPT_OK;
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__ERR:
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#ifdef CLEAN_STACK
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zeromem(buf, hLen);
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zeromem(md, sizeof(hash_state));
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#endif
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XFREE(buf);
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XFREE(md);
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return err;
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}
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#endif /* PKCS_1 */
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