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/* $OpenBSD: pkcs5_pbkdf2.c,v 1.6 2014/01/31 16:56:32 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>
/*
* HMAC-SHA-1 (from RFC 2202).
*/
static void
hmac_sha1(const u_int8_t *text, size_t text_len, const u_int8_t *key,
size_t key_len, u_int8_t digest[SHA1_DIGEST_LENGTH])
{
SHA1_CTX ctx;
u_int8_t k_pad[SHA1_BLOCK_LENGTH];
u_int8_t tk[SHA1_DIGEST_LENGTH];
int i;
if (key_len > SHA1_BLOCK_LENGTH) {
SHA1Init(&ctx);
SHA1Update(&ctx, key, key_len);
SHA1Final(tk, &ctx);
key = tk;
key_len = SHA1_DIGEST_LENGTH;
}
bzero(k_pad, sizeof k_pad);
bcopy(key, k_pad, key_len);
for (i = 0; i < SHA1_BLOCK_LENGTH; i++)
k_pad[i] ^= 0x36;
SHA1Init(&ctx);
SHA1Update(&ctx, k_pad, SHA1_BLOCK_LENGTH);
SHA1Update(&ctx, text, text_len);
SHA1Final(digest, &ctx);
bzero(k_pad, sizeof k_pad);
bcopy(key, k_pad, key_len);
for (i = 0; i < SHA1_BLOCK_LENGTH; i++)
k_pad[i] ^= 0x5c;
SHA1Init(&ctx);
SHA1Update(&ctx, k_pad, SHA1_BLOCK_LENGTH);
SHA1Update(&ctx, digest, SHA1_DIGEST_LENGTH);
SHA1Final(digest, &ctx);
}
/*
* 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;
hmac_sha1(asalt, salt_len + 4, pass, pass_len, d1);
memcpy(obuf, d1, sizeof(obuf));
for (i = 1; i < rounds; i++) {
hmac_sha1(d1, sizeof(d1), pass, pass_len, 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;
};
explicit_bzero(asalt, salt_len + 4);
free(asalt);
explicit_bzero(d1, sizeof(d1));
explicit_bzero(d2, sizeof(d2));
explicit_bzero(obuf, sizeof(obuf));
return 0;
}
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