/* p5_crpt2.c */
/* Written by Dr Stephen N Henson (steve@openssl.org) for the OpenSSL
 * project 1999.
 */
/* ====================================================================
 * Copyright (c) 1999 The OpenSSL Project.  All rights reserved.
 *
 * 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.
 *
 * 3. All advertising materials mentioning features or use of this
 *    software must display the following acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit. (http://www.OpenSSL.org/)"
 *
 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
 *    endorse or promote products derived from this software without
 *    prior written permission. For written permission, please contact
 *    licensing@OpenSSL.org.
 *
 * 5. Products derived from this software may not be called "OpenSSL"
 *    nor may "OpenSSL" appear in their names without prior written
 *    permission of the OpenSSL Project.
 *
 * 6. Redistributions of any form whatsoever must retain the following
 *    acknowledgment:
 *    "This product includes software developed by the OpenSSL Project
 *    for use in the OpenSSL Toolkit (http://www.OpenSSL.org/)"
 *
 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
 * EXPRESSED 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 OpenSSL PROJECT OR
 * ITS 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 product includes cryptographic software written by Eric Young
 * (eay@cryptsoft.com).  This product includes software written by Tim
 * Hudson (tjh@cryptsoft.com).
 *
 */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include "evp.h"
#include "hmac.h"

#define SHA_DIGEST_LENGTH 20

/* This is an implementation of PKCS#5 v2.0 password based encryption key
 * derivation function PBKDF2 using the only currently defined function HMAC
 * with SHA1. Verified against test vectors posted by Peter Gutmann
 * <pgut001@cs.auckland.ac.nz> to the PKCS-TNG <pkcs-tng@rsa.com> mailing list.
 */

int PKCS5_PBKDF2_HMAC_SHA1(const char *pass, int passlen,
			   const unsigned char *salt, int saltlen, int iter,
			   int keylen, unsigned char *out)
{
	unsigned char digtmp[SHA_DIGEST_LENGTH], *p, itmp[4];
	int cplen, j, k, tkeylen;
	unsigned long i = 1;
	HMAC_CTX hctx;

	HMAC_CTX_init(&hctx);
	p = out;
	tkeylen = keylen;
	if(!pass) passlen = 0;
	else if(passlen == -1) passlen = (int)strlen(pass);
	while(tkeylen) {
		if(tkeylen > SHA_DIGEST_LENGTH) cplen = SHA_DIGEST_LENGTH;
		else cplen = tkeylen;
		/* We are unlikely to ever use more than 256 blocks (5120 bits!)
		 * but just in case...
		 */
		itmp[0] = (unsigned char)((i >> 24) & 0xff);
		itmp[1] = (unsigned char)((i >> 16) & 0xff);
		itmp[2] = (unsigned char)((i >> 8) & 0xff);
		itmp[3] = (unsigned char)(i & 0xff);
		HMAC_Init_ex(&hctx, pass, passlen, EVP_sha1(), NULL);
		HMAC_Update(&hctx, salt, saltlen);
		HMAC_Update(&hctx, itmp, 4);
		HMAC_Final(&hctx, digtmp, NULL);
		memcpy(p, digtmp, cplen);
		for(j = 1; j < iter; j++) {
			HMAC(EVP_sha1(), pass, passlen,
				 digtmp, SHA_DIGEST_LENGTH, digtmp, NULL);
			for(k = 0; k < cplen; k++) p[k] ^= digtmp[k];
		}
		tkeylen-= cplen;
		i++;
		p+= cplen;
	}
	HMAC_CTX_cleanup(&hctx);
	return 1;
}