130 lines
3.6 KiB
C
130 lines
3.6 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@gmail.com, http://libtom.org
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*/
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#include <tomcrypt.h>
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/**
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@file pkcs_5_2.c
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LTC_PKCS #5, Algorithm #2, Tom St Denis
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*/
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#ifdef LTC_PKCS_5
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/**
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Execute LTC_PKCS #5 v2
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@param password The input password (or key)
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@param password_len The length of the password (octets)
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@param salt The salt (or nonce)
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@param salt_len The length of the salt (octets)
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@param iteration_count # of iterations desired for LTC_PKCS #5 v2 [read specs for more]
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@param hash_idx The index of the hash desired
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@param out [out] The destination for this algorithm
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@param outlen [in/out] The max size and resulting size of the algorithm output
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@return CRYPT_OK if successful
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*/
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int pkcs_5_alg2(const unsigned char *password, unsigned long password_len,
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const unsigned char *salt, unsigned long salt_len,
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int iteration_count, int hash_idx,
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unsigned char *out, unsigned long *outlen)
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{
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int err, itts;
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ulong32 blkno;
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unsigned long stored, left, x, y;
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unsigned char *buf[2];
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hmac_state *hmac;
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LTC_ARGCHK(password != NULL);
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LTC_ARGCHK(salt != NULL);
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LTC_ARGCHK(out != NULL);
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LTC_ARGCHK(outlen != NULL);
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/* test hash IDX */
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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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buf[0] = XMALLOC(MAXBLOCKSIZE * 2);
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hmac = XMALLOC(sizeof(hmac_state));
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if (hmac == NULL || buf[0] == NULL) {
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if (hmac != NULL) {
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XFREE(hmac);
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}
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if (buf[0] != NULL) {
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XFREE(buf[0]);
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}
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return CRYPT_MEM;
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}
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/* buf[1] points to the second block of MAXBLOCKSIZE bytes */
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buf[1] = buf[0] + MAXBLOCKSIZE;
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left = *outlen;
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blkno = 1;
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stored = 0;
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while (left != 0) {
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/* process block number blkno */
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zeromem(buf[0], MAXBLOCKSIZE*2);
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/* store current block number and increment for next pass */
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STORE32H(blkno, buf[1]);
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++blkno;
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/* get PRF(P, S||int(blkno)) */
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if ((err = hmac_init(hmac, hash_idx, password, password_len)) != CRYPT_OK) {
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goto LBL_ERR;
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}
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if ((err = hmac_process(hmac, salt, salt_len)) != CRYPT_OK) {
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goto LBL_ERR;
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}
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if ((err = hmac_process(hmac, buf[1], 4)) != CRYPT_OK) {
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goto LBL_ERR;
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}
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x = MAXBLOCKSIZE;
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if ((err = hmac_done(hmac, buf[0], &x)) != CRYPT_OK) {
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goto LBL_ERR;
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}
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/* now compute repeated and XOR it in buf[1] */
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XMEMCPY(buf[1], buf[0], x);
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for (itts = 1; itts < iteration_count; ++itts) {
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if ((err = hmac_memory(hash_idx, password, password_len, buf[0], x, buf[0], &x)) != CRYPT_OK) {
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goto LBL_ERR;
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}
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for (y = 0; y < x; y++) {
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buf[1][y] ^= buf[0][y];
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}
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}
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/* now emit upto x bytes of buf[1] to output */
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for (y = 0; y < x && left != 0; ++y) {
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out[stored++] = buf[1][y];
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--left;
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}
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}
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*outlen = stored;
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err = CRYPT_OK;
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LBL_ERR:
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#ifdef LTC_CLEAN_STACK
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zeromem(buf[0], MAXBLOCKSIZE*2);
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zeromem(hmac, sizeof(hmac_state));
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#endif
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XFREE(hmac);
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XFREE(buf[0]);
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return err;
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}
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#endif
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/* $Source$ */
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/* $Revision$ */
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/* $Date$ */
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