/* rsa_pss.c */

/*

 * Written by Dr Stephen N Henson (steve@openssl.org) 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

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

                         const EVP_MD *Hash, const unsigned char *EM,

                         int sLen)

{

    return RSA_verify_PKCS1_PSS_mgf1(rsa, mHash, Hash, NULL, EM, sLen);

}

int RSA_verify_PKCS1_PSS_mgf1(RSA *rsa, const unsigned char *mHash,

                              const EVP_MD *Hash, const EVP_MD *mgf1Hash,

                              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];

    EVP_MD_CTX_init(&ctx);

    if (mgf1Hash == NULL)

        mgf1Hash = Hash;

    hLen = EVP_MD_size(Hash);

    if (hLen < 0)

        goto err;

    /*-

     * 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_MGF1, 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_MGF1, RSA_R_FIRST_OCTET_INVALID);

        goto err;

    }

    if (MSBits == 0) {

        EM++;

        emLen--;

    }

    if (emLen < hLen + 2) {

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_DATA_TOO_LARGE);

        goto err;

    }

    if (sLen > emLen - hLen - 2) { /* sLen can be small negative */

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_DATA_TOO_LARGE);

        goto err;

    }

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

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, 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_MGF1, ERR_R_MALLOC_FAILURE);

        goto err;

    }

    if (PKCS1_MGF1(DB, maskedDBLen, H, hLen, mgf1Hash) < 0)

        goto err;

    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_MGF1, RSA_R_SLEN_RECOVERY_FAILED);

        goto err;

    }

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

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_SLEN_CHECK_FAILED);

        goto err;

    }

    if (!EVP_DigestInit_ex(&ctx, Hash, NULL)

        || !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes)

        || !EVP_DigestUpdate(&ctx, mHash, hLen))

        goto err;

    if (maskedDBLen - i) {

        if (!EVP_DigestUpdate(&ctx, DB + i, maskedDBLen - i))

            goto err;

    }

    if (!EVP_DigestFinal_ex(&ctx, H_, NULL))

        goto err;

    if (memcmp(H_, H, hLen)) {

        RSAerr(RSA_F_RSA_VERIFY_PKCS1_PSS_MGF1, RSA_R_BAD_SIGNATURE);

        ret = 0;

    } else

        ret = 1;

 err:

    if (DB)

        OPENSSL_free(DB);

    EVP_MD_CTX_cleanup(&ctx);

    return ret;

}

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

                              const unsigned char *mHash,

                              const EVP_MD *Hash, int sLen)

{

    return RSA_padding_add_PKCS1_PSS_mgf1(rsa, EM, mHash, Hash, NULL, sLen);

}

int RSA_padding_add_PKCS1_PSS_mgf1(RSA *rsa, unsigned char *EM,

                                   const unsigned char *mHash,

                                   const EVP_MD *Hash, const EVP_MD *mgf1Hash,

                                   int sLen)

{

    int i;

    int ret = 0;

    int hLen, maskedDBLen, MSBits, emLen;

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

    EVP_MD_CTX ctx;

    if (mgf1Hash == NULL)

        mgf1Hash = Hash;

    hLen = EVP_MD_size(Hash);

    if (hLen < 0)

        goto err;

    /*-

     * 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_MGF1, 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 (emLen < hLen + 2) {

        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1,

               RSA_R_DATA_TOO_LARGE_FOR_KEY_SIZE);

        goto err;

    }

    if (sLen == -2) {

        sLen = emLen - hLen - 2;

    } else if (sLen > emLen - hLen - 2) {

        RSAerr(RSA_F_RSA_PADDING_ADD_PKCS1_PSS_MGF1,

               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_MGF1,

                   ERR_R_MALLOC_FAILURE);

            goto err;

        }

        if (RAND_bytes(salt, sLen) <= 0)

            goto err;

    }

    maskedDBLen = emLen - hLen - 1;

    H = EM + maskedDBLen;

    EVP_MD_CTX_init(&ctx);

    if (!EVP_DigestInit_ex(&ctx, Hash, NULL)

        || !EVP_DigestUpdate(&ctx, zeroes, sizeof zeroes)

        || !EVP_DigestUpdate(&ctx, mHash, hLen))

        goto err;

    if (sLen && !EVP_DigestUpdate(&ctx, salt, sLen))

        goto err;

    if (!EVP_DigestFinal_ex(&ctx, H, NULL))

        goto err;

    EVP_MD_CTX_cleanup(&ctx);

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

    if (PKCS1_MGF1(EM, maskedDBLen, H, hLen, mgf1Hash))

        goto err;

    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