/* rsa_pss.c */

/* Written by Dr Stephen N Henson (shenson@bigfoot.com) for the OpenSSL

 * project 2005.

 */

/* ====================================================================

 * Copyright (c) 2005 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 "cryptlib.h"

#include <openssl/bn.h>

#include <openssl/rsa.h>

#include <openssl/evp.h>

#include <openssl/rand.h>

#include <openssl/sha.h>

static const unsigned char zeroes[] = {0,0,0,0,0,0,0,0};

#if defined(_MSC_VER) && defined(_ARM_)

#pragma optimize("g", off)

#endif

EXPORT_C int RSA_verify_PKCS1_PSS(RSA *rsa, const unsigned char *mHash,

			const EVP_MD *Hash, const unsigned char *EM, int sLen)

	{

	int i;

	int ret = 0;

	int hLen, maskedDBLen, MSBits, emLen;

	const unsigned char *H;

	unsigned char *DB = NULL;

	EVP_MD_CTX ctx;

	unsigned char H_[EVP_MAX_MD_SIZE];

	hLen = EVP_MD_size(Hash);

	/*

	 * Negative sLen has special meanings:

	 *	-1	sLen == hLen

	 *	-2	salt length is autorecovered from signature

	 *	-N	reserved

	 */

	if      (sLen == -1)	sLen = hLen;

	else if (sLen == -2)	sLen = -2;

	else if (sLen < -2)

		{

		RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);

		goto err;

		}

	MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;

	emLen = RSA_size(rsa);

	if (EM[0] & (0xFF << MSBits))

		{

		RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_FIRST_OCTET_INVALID);

		goto err;

		}

	if (MSBits == 0)

		{

		EM++;

		emLen--;

		}

	if (emLen < (hLen + sLen + 2)) /* sLen can be small negative */

		{

		RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_DATA_TOO_LARGE);

		goto err;

		}

	if (EM[emLen - 1] != 0xbc)

		{

		RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_LAST_OCTET_INVALID);

		goto err;

		}

	maskedDBLen = emLen - hLen - 1;

	H = EM + maskedDBLen;

	DB = OPENSSL_malloc(maskedDBLen);

	if (!DB)

		{

		RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, ERR_R_MALLOC_FAILURE);

		goto err;

		}

	PKCS1_MGF1(DB, maskedDBLen, H, hLen, Hash);

	for (i = 0; i < maskedDBLen; i++)

		DB[i] ^= EM[i];

	if (MSBits)

		DB[0] &= 0xFF >> (8 - MSBits);

	for (i = 0; DB[i] == 0 && i < (maskedDBLen-1); i++) ;

	if (DB[i++] != 0x1)

		{

		RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_RECOVERY_FAILED);

		goto err;

		}

	if (sLen >= 0 && (maskedDBLen - i) != sLen)

		{

		RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);

		goto err;

		}

	EVP_MD_CTX_init(&ctx);

	EVP_DigestInit_ex(&ctx, Hash, NULL);

	EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes);

	EVP_DigestUpdate(&ctx, mHash, hLen);

	if (maskedDBLen - i)

		EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i);

	EVP_DigestFinal(&ctx, H_, NULL);

	EVP_MD_CTX_cleanup(&ctx);

	if (memcmp(H_, H, hLen))

		{

		RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS, RSA_R_BAD_SIGNATURE);

		ret = 0;

		}

	else 

		ret = 1;

	err:

	if (DB)

		OPENSSL_free(DB);

	return ret;

	}

EXPORT_C int RSA_padding_add_PKCS1_PSS(RSA *rsa, unsigned char *EM,

			const unsigned char *mHash,

			const EVP_MD *Hash, int sLen)

	{

	int i;

	int ret = 0;

	int hLen, maskedDBLen, MSBits, emLen;

	unsigned char *H, *salt = NULL, *p;

	EVP_MD_CTX ctx;

	hLen = EVP_MD_size(Hash);

	/*

	 * Negative sLen has special meanings:

	 *	-1	sLen == hLen

	 *	-2	salt length is maximized

	 *	-N	reserved

	 */

	if      (sLen == -1)	sLen = hLen;

	else if (sLen == -2)	sLen = -2;

	else if (sLen < -2)

		{

		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS, RSA_R_SLEN_CHECK_FAILED);

		goto err;

		}

	MSBits = (BN_num_bits(rsa->n) - 1) & 0x7;

	emLen = RSA_size(rsa);

	if (MSBits == 0)

		{

		*EM++ = 0;

		emLen--;

		}

	if (sLen == -2)

		{

		sLen = emLen - hLen - 2;

		}

	else if (emLen < (hLen + sLen + 2))

		{

		RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS,

		   RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);

		goto err;

		}

	if (sLen > 0)

		{

		salt = OPENSSL_malloc(sLen);

		if (!salt)

			{

			RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS,

		   		ERR_R_MALLOC_FAILURE);

			goto err;

			}

		if (!RAND_bytes(salt, sLen))

			goto err;

		}

	maskedDBLen = emLen - hLen - 1;

	H = EM + maskedDBLen;

	EVP_MD_CTX_init(&ctx);

	EVP_DigestInit_ex(&ctx, Hash, NULL);

	EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes);

	EVP_DigestUpdate(&ctx, mHash, hLen);

	if (sLen)

		EVP_DigestUpdate(&ctx, salt, sLen);

	EVP_DigestFinal(&ctx, H, NULL);

	EVP_MD_CTX_cleanup(&ctx);

	/* Generate dbMask in place then perform XOR on it */

	PKCS1_MGF1(EM, maskedDBLen, H, hLen, Hash);

	p = EM;

	/* Initial PS XORs with all zeroes which is a NOP so just update

	 * pointer. Note from a test above this value is guaranteed to

	 * be non-negative.

	 */

	p += emLen - sLen - hLen - 2;

	*p++ ^= 0x1;

	if (sLen > 0)

		{

		for (i = 0; i < sLen; i++)

			*p++ ^= salt[i];

		}

	if (MSBits)

		EM[0] &= 0xFF >> (8 - MSBits);

	/* H is already in place so just set final 0xbc */

	EM[emLen - 1] = 0xbc;

	ret = 1;

	err:

	if (salt)

		OPENSSL_free(salt);

	return ret;

	}

#if defined(_MSC_VER)

#pragma optimize("",on)

#endif