/* $OpenBSD: pkcs5_pbkdf2.c,v 1.4 2013/06/03 21:07:02 tedu Exp $ */

/*-

* Copyright (c) 2008 Damien Bergamini <damien.bergamini@free.fr>

*

* Permission to use, copy, modify, and distribute this software for any

* purpose with or without fee is hereby granted, provided that the above

* copyright notice and this permission notice appear in all copies.

*

* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES

* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF

* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR

* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN

* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF

* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.

*/

#include <sys/types.h>

#include <sys/param.h>

#include <string.h>

#include <limits.h>

#include <stdlib.h>

//#include <util.h>

#include "sha1.h"

/*

* Password-Based Key Derivation Function 2 (PKCS #5 v2.0).

* Code based on IEEE Std 802.11-2007, Annex H.4.2.

*/

int

pkcs5_pbkdf2(const char *pass, size_t pass_len, const uint8_t *salt, size_t salt_len,

uint8_t *key, size_t key_len, unsigned int rounds)

{

uint8_t *asalt, obuf[SHA1_DIGEST_LENGTH];

uint8_t d1[SHA1_DIGEST_LENGTH], d2[SHA1_DIGEST_LENGTH];

unsigned int i, j;

unsigned int count;

size_t r;

if (rounds < 1 || key_len == 0)

return -1;

if (salt_len == 0 || salt_len > SIZE_MAX - 4)

return -1;

if ((asalt = malloc(salt_len + 4)) == NULL)

return -1;

memcpy(asalt, salt, salt_len);

for (count = 1; key_len > 0; count++) {

asalt[salt_len + 0] = (count >> 24) & 0xff;

asalt[salt_len + 1] = (count >> 16) & 0xff;

asalt[salt_len + 2] = (count >> 8) & 0xff;

asalt[salt_len + 3] = count & 0xff;

SHA1Hmac((const uint8_t *) pass, pass_len, asalt, salt_len + 4, d1);

memcpy(obuf, d1, sizeof(obuf));

for (i = 1; i < rounds; i++) {

SHA1Hmac((const uint8_t *) pass, pass_len, d1, sizeof(d1), d2);

memcpy(d1, d2, sizeof(d1));

for (j = 0; j < sizeof(obuf); j++)

obuf[j] ^= d1[j];

}

r = MIN(key_len, SHA1_DIGEST_LENGTH);

memcpy(key, obuf, r);

key += r;

key_len -= r;

};

bzero(asalt, salt_len + 4);

free(asalt);

bzero(d1, sizeof(d1));

bzero(d2, sizeof(d2));

bzero(obuf, sizeof(obuf));

return 0;

}