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/* $OpenBSD: pkcs5_pbkdf2.c,v 1.3 2012/09/09 18:08:21 matthew Exp $ */
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/*-
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* Copyright (c) 2008 Damien Bergamini <damien.bergamini@free.fr>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*/
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#include <sys/types.h>
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#include <sys/param.h>
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#include <string.h>
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#include <limits.h>
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#include <stdlib.h>
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#include <util.h>
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#include <sha1.h>
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/*
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* HMAC-SHA-1 (from RFC 2202).
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*/
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static void
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hmac_sha1(const u_int8_t *text, size_t text_len, const u_int8_t *key,
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size_t key_len, u_int8_t digest[SHA1_DIGEST_LENGTH])
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{
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SHA1_CTX ctx;
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u_int8_t k_pad[SHA1_BLOCK_LENGTH];
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u_int8_t tk[SHA1_DIGEST_LENGTH];
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int i;
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if (key_len > SHA1_BLOCK_LENGTH) {
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SHA1Init(&ctx);
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SHA1Update(&ctx, key, key_len);
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SHA1Final(tk, &ctx);
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key = tk;
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key_len = SHA1_DIGEST_LENGTH;
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}
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bzero(k_pad, sizeof k_pad);
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bcopy(key, k_pad, key_len);
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for (i = 0; i < SHA1_BLOCK_LENGTH; i++)
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k_pad[i] ^= 0x36;
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SHA1Init(&ctx);
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SHA1Update(&ctx, k_pad, SHA1_BLOCK_LENGTH);
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SHA1Update(&ctx, text, text_len);
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SHA1Final(digest, &ctx);
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bzero(k_pad, sizeof k_pad);
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bcopy(key, k_pad, key_len);
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for (i = 0; i < SHA1_BLOCK_LENGTH; i++)
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k_pad[i] ^= 0x5c;
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SHA1Init(&ctx);
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SHA1Update(&ctx, k_pad, SHA1_BLOCK_LENGTH);
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SHA1Update(&ctx, digest, SHA1_DIGEST_LENGTH);
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SHA1Final(digest, &ctx);
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}
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/*
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* Password-Based Key Derivation Function 2 (PKCS #5 v2.0).
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* Code based on IEEE Std 802.11-2007, Annex H.4.2.
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*/
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int
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pkcs5_pbkdf2(const char *pass, size_t pass_len, const char *salt, size_t salt_len,
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u_int8_t *key, size_t key_len, unsigned int rounds)
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{
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u_int8_t *asalt, obuf[SHA1_DIGEST_LENGTH];
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u_int8_t d1[SHA1_DIGEST_LENGTH], d2[SHA1_DIGEST_LENGTH];
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unsigned int i, j;
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unsigned int count;
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size_t r;
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if (rounds < 1 || key_len == 0)
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return -1;
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if (salt_len == 0 || salt_len > SIZE_MAX - 4)
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return -1;
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if ((asalt = malloc(salt_len + 4)) == NULL)
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return -1;
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memcpy(asalt, salt, salt_len);
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for (count = 1; key_len > 0; count++) {
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asalt[salt_len + 0] = (count >> 24) & 0xff;
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asalt[salt_len + 1] = (count >> 16) & 0xff;
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asalt[salt_len + 2] = (count >> 8) & 0xff;
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asalt[salt_len + 3] = count & 0xff;
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hmac_sha1(asalt, salt_len + 4, pass, pass_len, d1);
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memcpy(obuf, d1, sizeof(obuf));
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for (i = 1; i < rounds; i++) {
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hmac_sha1(d1, sizeof(d1), pass, pass_len, d2);
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memcpy(d1, d2, sizeof(d1));
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for (j = 0; j < sizeof(obuf); j++)
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obuf[j] ^= d1[j];
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}
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r = MIN(key_len, SHA1_DIGEST_LENGTH);
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memcpy(key, obuf, r);
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key += r;
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key_len -= r;
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};
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bzero(asalt, salt_len + 4);
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free(asalt);
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bzero(d1, sizeof(d1));
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bzero(d2, sizeof(d2));
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bzero(obuf, sizeof(obuf));
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return 0;
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}
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