/*
 * Copyright (c) 2012 William Pitcock <nenolod@dereferenced.org>.
 *
 * Permission to use, copy, modify, and/or 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.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``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 AUTHOR 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.
 */

#include "atheme.h"

#ifdef HAVE_OPENSSL

DECLARE_MODULE_V1("crypto/pbkdf2", false, _modinit, _moddeinit, PACKAGE_VERSION, VENDOR_STRING);

#include <openssl/evp.h>
#include <openssl/sha.h>
#include <openssl/hmac.h>

#define ROUNDS		(128000)
#define SALTLEN		(16)

static const char *pbkdf2_salt(void)
{
	static char buf[SALTLEN + 1];
	char *randstr = random_string(SALTLEN);

	mowgli_strlcpy(buf, randstr, sizeof buf);

	free(randstr);

	return buf;
}

static const char *pbkdf2_crypt(const char *key, const char *salt)
{
	static char outbuf[PASSLEN];
	static unsigned char digestbuf[SHA512_DIGEST_LENGTH];
	int res, iter;

	if (strlen(salt) < SALTLEN)
		salt = pbkdf2_salt();

	memcpy(outbuf, salt, SALTLEN);

	res = PKCS5_PBKDF2_HMAC(key, strlen(key), (const unsigned char *)salt, SALTLEN, ROUNDS, EVP_sha512(), SHA512_DIGEST_LENGTH, digestbuf);

	for (iter = 0; iter < SHA512_DIGEST_LENGTH; iter++)
		sprintf(outbuf + SALTLEN + (iter * 2), "%02x", 255 & digestbuf[iter]);

	return outbuf;
}

static crypt_impl_t pbkdf2_crypt_impl = {
	.id = "pbkdf2",
	.crypt = &pbkdf2_crypt,
	.salt = &pbkdf2_salt
};

void _modinit(module_t *m)
{
	crypt_register(&pbkdf2_crypt_impl);
}

void _moddeinit(module_unload_intent_t intent)
{
	crypt_unregister(&pbkdf2_crypt_impl);
}

#endif