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rsa_pss.c

/* 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)
      {
      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 = M_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;

      }

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 = M_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) <= 0)
                  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

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