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/* $OpenBSD: pbkdf2.c,v 1.1 2008/06/14 06:28:27 djm 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 <u.h>
#include <libc.h>
#include <mp.h>
#include <libsec.h>
#define DS DigestState /* only to abbreviate SYNOPSIS */
#define SHA1_DIGEST_LENGTH 20
#define MIN(a,b) ((a < b) ? a : b)
/*
* 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 unsigned char *pass, int pass_len, const unsigned char *salt, int salt_len,
unsigned char *key, int key_len, int rounds)
{
unsigned char *asalt, obuf[SHA1_DIGEST_LENGTH];
unsigned char d1[SHA1_DIGEST_LENGTH], d2[SHA1_DIGEST_LENGTH];
unsigned i, j;
unsigned count;
unsigned r;
if (rounds < 1 || key_len == 0)
return -1;
if (salt_len == 0)
return -1;
if ((asalt = malloc(salt_len + 4)) == nil)
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;
hmac_sha1(asalt, salt_len + 4, pass, pass_len, d1, nil);
memcpy(obuf, d1, sizeof(obuf));
for (i = 1; i < rounds; i++) {
hmac_sha1(d1, sizeof(d1), pass, pass_len, d2, nil);
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;
};
memset(asalt, 0, salt_len + 4);
free(asalt);
memset(d1, 0, sizeof(d1));
memset(d2, 0, sizeof(d2));
memset(obuf, 0, sizeof(obuf));
return 0;
}
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