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/* 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@gmail.com, http://libtomcrypt.com
*/
#include <tomcrypt.h>
/**
@file pkcs_5_2.c
PKCS #5, Algorithm #2, Tom St Denis
*/
#ifdef PKCS_5
/**
Execute PKCS #5 v2
@param password The input password (or key)
@param password_len The length of the password (octets)
@param salt The salt (or nonce)
@param salt_len The length of the salt (octets)
@param iteration_count # of iterations desired for PKCS #5 v2 [read specs for more]
@param hash_idx The index of the hash desired
@param out [out] The destination for this algorithm
@param outlen [in/out] The max size and resulting size of the algorithm output
@return CRYPT_OK if successful
*/
int pkcs_5_alg2(const unsigned char *password, unsigned long password_len,
const unsigned char *salt, unsigned long salt_len,
int iteration_count, int hash_idx,
unsigned char *out, unsigned long *outlen)
{
int err, itts;
ulong32 blkno;
unsigned long stored, left, x, y;
unsigned char *buf[2];
hmac_state *hmac;
LTC_ARGCHK(password != NULL);
LTC_ARGCHK(salt != NULL);
LTC_ARGCHK(out != NULL);
LTC_ARGCHK(outlen != NULL);
/* test hash IDX */
if ((err = hash_is_valid(hash_idx)) != CRYPT_OK) {
return err;
}
buf[0] = XMALLOC(MAXBLOCKSIZE * 2);
hmac = XMALLOC(sizeof(hmac_state));
if (hmac == NULL || buf[0] == NULL) {
if (hmac != NULL) {
XFREE(hmac);
}
if (buf[0] != NULL) {
XFREE(buf[0]);
}
return CRYPT_MEM;
}
/* buf[1] points to the second block of MAXBLOCKSIZE bytes */
buf[1] = buf[0] + MAXBLOCKSIZE;
left = *outlen;
blkno = 1;
stored = 0;
while (left != 0) {
/* process block number blkno */
zeromem(buf[0], MAXBLOCKSIZE*2);
/* store current block number and increment for next pass */
STORE32H(blkno, buf[1]);
++blkno;
/* get PRF(P, S||int(blkno)) */
if ((err = hmac_init(hmac, hash_idx, password, password_len)) != CRYPT_OK) {
goto LBL_ERR;
}
if ((err = hmac_process(hmac, salt, salt_len)) != CRYPT_OK) {
goto LBL_ERR;
}
if ((err = hmac_process(hmac, buf[1], 4)) != CRYPT_OK) {
goto LBL_ERR;
}
x = MAXBLOCKSIZE;
if ((err = hmac_done(hmac, buf[0], &x)) != CRYPT_OK) {
goto LBL_ERR;
}
/* now compute repeated and XOR it in buf[1] */
XMEMCPY(buf[1], buf[0], x);
for (itts = 1; itts < iteration_count; ++itts) {
if ((err = hmac_memory(hash_idx, password, password_len, buf[0], x, buf[0], &x)) != CRYPT_OK) {
goto LBL_ERR;
}
for (y = 0; y < x; y++) {
buf[1][y] ^= buf[0][y];
}
}
/* now emit upto x bytes of buf[1] to output */
for (y = 0; y < x && left != 0; ++y) {
out[stored++] = buf[1][y];
--left;
}
}
*outlen = stored;
err = CRYPT_OK;
LBL_ERR:
#ifdef LTC_CLEAN_STACK
zeromem(buf[0], MAXBLOCKSIZE*2);
zeromem(hmac, sizeof(hmac_state));
#endif
XFREE(hmac);
XFREE(buf[0]);
return err;
}
#endif
/* $Source: /cvs/libtom/libtomcrypt/src/misc/pkcs5/pkcs_5_2.c,v $ */
/* $Revision: 1.5 $ */
/* $Date: 2006/03/31 14:15:35 $ */
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