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/* $NetBSD: pkcs5_pbkdf2.c,v 1.5 2004/03/17 01:29:13 dan Exp $ */
/*-
* Copyright (c) 2002, 2003 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Roland C. Dowdeswell.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
/*
* This code is an implementation of PKCS #5 PBKDF2 which is described
* in:
*
* ``PKCS #5 v2.0: Password-Based Cryptography Standard'', RSA Laboratories,
* March 25, 1999.
*
* and can be found at the following URL:
*
* http://www.rsasecurity.com/rsalabs/pkcs/pkcs-5/
*
* It was also republished as RFC 2898.
*/
#include <sys/types.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <assert.h>
#include <err.h>
#include <stdlib.h>
#include <string.h>
#include <openssl/hmac.h>
#include "pkcs5_pbkdf2.h"
static void int_encode(u_int8_t *, int);
static void prf_iterate(u_int8_t *, const u_int8_t *, int,
const u_int8_t *, int, int, int);
static void
memxor(void *res, const void *src, size_t len)
{
size_t i;
char *r;
const char *s;
r = res;
s = src;
for (i=0; i < len; i++)
r[i] ^= s[i];
}
#define PRF_BLOCKLEN 20
/*
* int_encode encodes i as a four octet integer, most significant
* octet first. (from the end of Step 3).
*/
static void
int_encode(u_int8_t *res, int i)
{
*res++ = (i >> 24) & 0xff;
*res++ = (i >> 16) & 0xff;
*res++ = (i >> 8) & 0xff;
*res = (i ) & 0xff;
}
static void
prf_iterate(u_int8_t *r, const u_int8_t *P, int Plen,
const u_int8_t *S, int Slen, int c, int ind)
{
int first_time = 1;
int i;
int datalen;
int tmplen;
u_int8_t *data;
u_int8_t tmp[EVP_MAX_MD_SIZE];
data = malloc(Slen + 4);
if (!data)
err(1, "prf_iterate");
memcpy(data, S, Slen);
int_encode(data + Slen, ind);
datalen = Slen + 4;
for (i=0; i < c; i++) {
HMAC(EVP_sha1(), P, Plen, data, datalen, tmp, &tmplen);
assert(tmplen == PRF_BLOCKLEN);
if (first_time) {
memcpy(r, tmp, PRF_BLOCKLEN);
first_time = 0;
} else
memxor(r, tmp, PRF_BLOCKLEN);
memcpy(data, tmp, PRF_BLOCKLEN);
datalen = PRF_BLOCKLEN;
}
free(data);
}
/*
* pkcs5_pbkdf2 takes all of its lengths in bytes.
*/
int
pkcs5_pbkdf2(u_int8_t **r, int dkLen, const u_int8_t *P, int Plen,
const u_int8_t *S, int Slen, int c, int compat)
{
int i;
int l;
/* sanity */
if (!r)
return -1;
if (dkLen <= 0)
return -1;
if (c < 1)
return -1;
/* Step 2 */
l = (dkLen + PRF_BLOCKLEN - 1) / PRF_BLOCKLEN;
/* allocate the output */
*r = calloc(l, PRF_BLOCKLEN);
if (!*r)
return -1;
/* Step 3 */
for (i=0; i < l; i++)
prf_iterate(*r + (PRF_BLOCKLEN * i), P, Plen, S, Slen, c,
(compat?i:i+1));
/* Step 4 and 5
* by the structure of the code, we do not need to concatenate
* the blocks, they're already concatenated. We do not extract
* the first dkLen octets, since we [naturally] assume that the
* calling function will use only the octets that it needs and
* the free(3) will free all of the allocated memory.
*/
return 0;
}
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