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pkcs5_pbkdf2.c revision 1.1 
      1 /* $NetBSD: pkcs5_pbkdf2.c,v 1.1 2002/10/04 18:37:20 elric Exp $ */
      2 
      3 /*-
      4  * Copyright (c) 2002 The NetBSD Foundation, Inc.
      5  * All rights reserved.
      6  *
      7  * This code is derived from software contributed to The NetBSD Foundation
      8  * by Roland C. Dowdeswell.
      9  *
     10  * Redistribution and use in source and binary forms, with or without
     11  * modification, are permitted provided that the following conditions
     12  * are met:
     13  * 1. Redistributions of source code must retain the above copyright
     14  *    notice, this list of conditions and the following disclaimer.
     15  * 2. Redistributions in binary form must reproduce the above copyright
     16  *    notice, this list of conditions and the following disclaimer in the
     17  *    documentation and/or other materials provided with the distribution.
     18  * 3. All advertising materials mentioning features or use of this software
     19  *    must display the following acknowledgement:
     20  *        This product includes software developed by the NetBSD
     21  *        Foundation, Inc. and its contributors.
     22  * 4. Neither the name of The NetBSD Foundation nor the names of its
     23  *    contributors may be used to endorse or promote products derived
     24  *    from this software without specific prior written permission.
     25  *
     26  * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
     27  * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
     28  * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
     29  * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
     30  * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
     31  * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
     32  * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
     33  * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
     34  * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
     35  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
     36  * POSSIBILITY OF SUCH DAMAGE.
     37  */
     38 
     39 /*
     40  * This code is an implementation of PKCS #5 PBKDF2 which is described
     41  * in:
     42  *
     43  * ``PKCS #5 v2.0: Password-Based Cryptography Standard'', RSA Laboratories,
     44  * March 25, 1999.
     45  *
     46  * and can be found at the following URL:
     47  *
     48  *	http://www.rsasecurity.com/rsalabs/pkcs/pkcs-5/
     49  *
     50  * It was also republished as RFC 2898.
     51  */
     52 
     53 
     54 #include <sys/cdefs.h>
     55 #ifndef lint
     56 __RCSID("$NetBSD: pkcs5_pbkdf2.c,v 1.1 2002/10/04 18:37:20 elric Exp $");
     57 #endif
     58 
     59 #include <assert.h>
     60 #include <malloc.h>
     61 #include <stdlib.h>
     62 #include <string.h>
     63 
     64 #include <openssl/hmac.h>
     65 
     66 #include "pkcs5_pbkdf2.h"
     67 #include "utils.h"
     68 
     69 static void	int_encode(u_int8_t *, int);
     70 static void	prf_iterate(u_int8_t *, const u_int8_t *, int,
     71 			    const u_int8_t *, int, int, int);
     72 
     73 #define PRF_BLOCKLEN	20
     74 
     75 /*
     76  * int_encode encodes i as a four octet integer, most significant
     77  * octet first.  (from the end of Step 3).
     78  */
     79 
     80 static void
     81 int_encode(u_int8_t *res, int i)
     82 {
     83 
     84 	*res++ = (i >> 24) & 0xff;
     85 	*res++ = (i >> 16) & 0xff;
     86 	*res++ = (i >>  8) & 0xff;
     87 	*res   = (i      ) & 0xff;
     88 }
     89 
     90 void
     91 prf_iterate(u_int8_t *r, const u_int8_t *P, int Plen,
     92 	    const u_int8_t *S, int Slen, int c, int ind)
     93 {
     94 	int		 first_time = 1;
     95 	int		 i;
     96 	int		 datalen;
     97 	int		 tmplen;
     98 	u_int8_t	*data;
     99 	u_int8_t	 tmp[EVP_MAX_MD_SIZE];
    100 
    101 	data = malloc(Slen + 4);
    102 	memcpy(data, S, Slen);
    103 	int_encode(data + Slen, ind);
    104 	datalen = Slen + 4;
    105 
    106 	for (i=0; i < c; i++) {
    107 		HMAC(EVP_sha1(), P, Plen, data, datalen, tmp, &tmplen);
    108 
    109 		assert(tmplen == PRF_BLOCKLEN);
    110 
    111 		if (first_time) {
    112 			memcpy(r, tmp, PRF_BLOCKLEN);
    113 			first_time = 0;
    114 		} else
    115 			memxor(r, tmp, PRF_BLOCKLEN);
    116 		memcpy(data, tmp, PRF_BLOCKLEN);
    117 		datalen = PRF_BLOCKLEN;
    118 	}
    119 	free(data);
    120 }
    121 
    122 /*
    123  * pkcs5_pbkdf2 takes all of its lengths in bytes.
    124  */
    125 
    126 int
    127 pkcs5_pbkdf2(u_int8_t **r, int dkLen, const u_int8_t *P, int Plen,
    128 	     const u_int8_t *S, int Slen, int c)
    129 {
    130 	int	i;
    131 	int	l;
    132 
    133 	/* sanity */
    134 	if (!r)
    135 		return -1;
    136 	if (dkLen <= 0)
    137 		return -1;
    138 	if (c < 1)
    139 		return -1;
    140 
    141 	/* Step 2 */
    142 	l = (dkLen + PRF_BLOCKLEN - 1) / PRF_BLOCKLEN;
    143 
    144 	/* allocate the output */
    145 	*r = malloc(l * PRF_BLOCKLEN);
    146 	if (!*r)
    147 		return -1;
    148 
    149 	/* Step 3 */
    150 	for (i=0; i < l; i++)
    151 		prf_iterate(*r + (PRF_BLOCKLEN * i), P, Plen, S, Slen, c, i);
    152 
    153 	/* Step 4 and 5
    154 	 *  by the structure of the code, we do not need to concatenate
    155 	 *  the blocks, they're already concatenated.  We do not extract
    156 	 *  the first dkLen octets, since we [naturally] assume that the
    157 	 *  calling function will use only the octets that it needs and
    158 	 *  the free(3) will free all of the allocated memory.
    159 	 */
    160 	return 0;
    161 }
    162