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fips_rsa_eay.c

/* crypto/rsa/rsa_eay.c */
/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young (eay@cryptsoft.com).
 * The implementation was written so as to conform with Netscapes SSL.
 * 
 * This library is free for commercial and non-commercial use as long as
 * the following conditions are aheared to.  The following conditions
 * apply to all code found in this distribution, be it the RC4, RSA,
 * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
 * included with this distribution is covered by the same copyright terms
 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
 * 
 * Copyright remains Eric Young's, and as such any Copyright notices in
 * the code are not to be removed.
 * If this package is used in a product, Eric Young should be given attribution
 * as the author of the parts of the library used.
 * This can be in the form of a textual message at program startup or
 * in documentation (online or textual) provided with the package.
 * 
 * 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 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 acknowledgement:
 *    "This product includes cryptographic software written by
 *     Eric Young (eay@cryptsoft.com)"
 *    The word 'cryptographic' can be left out if the rouines from the library
 *    being used are not cryptographic related :-).
 * 4. If you include any Windows specific code (or a derivative thereof) from 
 *    the apps directory (application code) you must include an acknowledgement:
 *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
 * 
 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``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 OR 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.
 * 
 * The licence and distribution terms for any publically available version or
 * derivative of this code cannot be changed.  i.e. this code cannot simply be
 * copied and put under another distribution licence
 * [including the GNU Public Licence.]
 */

#include <stdio.h>
#include <openssl/err.h>
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/rand.h>
#include <openssl/fips.h>

#if !defined(RSA_NULL) && defined(OPENSSL_FIPS)

static int RSA_eay_public_encrypt(FIPS_RSA_SIZE_T flen, const unsigned char *from,
            unsigned char *to, RSA *rsa,int padding);
static int RSA_eay_private_encrypt(FIPS_RSA_SIZE_T flen, const unsigned char *from,
            unsigned char *to, RSA *rsa,int padding);
static int RSA_eay_public_decrypt(FIPS_RSA_SIZE_T flen, const unsigned char *from,
            unsigned char *to, RSA *rsa,int padding);
static int RSA_eay_private_decrypt(FIPS_RSA_SIZE_T flen, const unsigned char *from,
            unsigned char *to, RSA *rsa,int padding);
static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa);
static int RSA_eay_init(RSA *rsa);
static int RSA_eay_finish(RSA *rsa);
static RSA_METHOD rsa_pkcs1_eay_meth={
      "Eric Young's PKCS#1 RSA",
      RSA_eay_public_encrypt,
      RSA_eay_public_decrypt, /* signature verification */
      RSA_eay_private_encrypt, /* signing */
      RSA_eay_private_decrypt,
      RSA_eay_mod_exp,
      BN_mod_exp_mont, /* XXX probably we should not use Montgomery if  e == 3 */
      RSA_eay_init,
      RSA_eay_finish,
      0, /* flags */
      NULL,
      0, /* rsa_sign */
      0  /* rsa_verify */
      };

const RSA_METHOD *RSA_PKCS1_SSLeay(void)
      {
      return(&rsa_pkcs1_eay_meth);
      }

static int RSA_eay_public_encrypt(FIPS_RSA_SIZE_T flen, const unsigned char *from,
           unsigned char *to, RSA *rsa, int padding)
      {
      BIGNUM f,ret;
      int i,j,k,num=0,r= -1;
      unsigned char *buf=NULL;
      BN_CTX *ctx=NULL;

      BN_init(&f);
      BN_init(&ret);

      if(FIPS_selftest_failed())
            {
            FIPSerr(FIPS_F_RSA_EAY_PUBLIC_ENCRYPT,FIPS_R_FIPS_SELFTEST_FAILED);
            goto err;
            }

      if ((ctx=BN_CTX_new()) == NULL) goto err;
      num=BN_num_bytes(rsa->n);
      if ((buf=(unsigned char *)OPENSSL_malloc(num)) == NULL)
            {
            RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT,ERR_R_MALLOC_FAILURE);
            goto err;
            }

      switch (padding)
            {
      case RSA_PKCS1_PADDING:
            i=RSA_padding_add_PKCS1_type_2(buf,num,from,flen);
            break;
#ifndef OPENSSL_NO_SHA
      case RSA_PKCS1_OAEP_PADDING:
              i=RSA_padding_add_PKCS1_OAEP(buf,num,from,flen,NULL,0);
            break;
#endif
      case RSA_SSLV23_PADDING:
            i=RSA_padding_add_SSLv23(buf,num,from,flen);
            break;
      case RSA_NO_PADDING:
            i=RSA_padding_add_none(buf,num,from,flen);
            break;
      default:
            RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT,RSA_R_UNKNOWN_PADDING_TYPE);
            goto err;
            }
      if (i <= 0) goto err;

      if (BN_bin2bn(buf,num,&f) == NULL) goto err;
      
      if (BN_ucmp(&f, rsa->n) >= 0)
            {     
            /* usually the padding functions would catch this */
            RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT,RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
            goto err;
            }

      if ((rsa->_method_mod_n == NULL) && (rsa->flags & RSA_FLAG_CACHE_PUBLIC))
            {
            BN_MONT_CTX* bn_mont_ctx;
            if ((bn_mont_ctx=BN_MONT_CTX_new()) == NULL)
                  goto err;
            if (!BN_MONT_CTX_set(bn_mont_ctx,rsa->n,ctx))
                  {
                  BN_MONT_CTX_free(bn_mont_ctx);
                  goto err;
                  }
            if (rsa->_method_mod_n == NULL) /* other thread may have finished first */
                  {
                  CRYPTO_w_lock(CRYPTO_LOCK_RSA);
                  if (rsa->_method_mod_n == NULL)
                        {
                        rsa->_method_mod_n = bn_mont_ctx;
                        bn_mont_ctx = NULL;
                        }
                  CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
                  }
            if (bn_mont_ctx)
                  BN_MONT_CTX_free(bn_mont_ctx);
            }
            
      if (!rsa->meth->bn_mod_exp(&ret,&f,rsa->e,rsa->n,ctx,
            rsa->_method_mod_n)) goto err;

      /* put in leading 0 bytes if the number is less than the
       * length of the modulus */
      j=BN_num_bytes(&ret);
      i=BN_bn2bin(&ret,&(to[num-j]));
      for (k=0; k<(num-i); k++)
            to[k]=0;

      r=num;
err:
      if (ctx != NULL) BN_CTX_free(ctx);
      BN_clear_free(&f);
      BN_clear_free(&ret);
      if (buf != NULL) 
            {
            OPENSSL_cleanse(buf,num);
            OPENSSL_free(buf);
            }
      return(r);
      }

static int rsa_eay_blinding(RSA *rsa, BN_CTX *ctx)
      {
      int ret = 1;
      CRYPTO_w_lock(CRYPTO_LOCK_RSA);
      /* Check again inside the lock - the macro's check is racey */
      if(rsa->blinding == NULL)
            ret = RSA_blinding_on(rsa, ctx);
      CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
      return ret;
      }

#define BLINDING_HELPER(rsa, ctx, err_instr) \
      do { \
            if((!((rsa)->flags & RSA_FLAG_NO_BLINDING)) && \
                ((rsa)->blinding == NULL) && \
                !rsa_eay_blinding(rsa, ctx)) \
                err_instr \
      } while(0)

static BN_BLINDING *setup_blinding(RSA *rsa, BN_CTX *ctx)
      {
      BIGNUM *A, *Ai;
      BN_BLINDING *ret = NULL;

      /* added in OpenSSL 0.9.6j and 0.9.7b */

      /* NB: similar code appears in RSA_blinding_on (rsa_lib.c);
       * this should be placed in a new function of its own, but for reasons
       * of binary compatibility can't */

      BN_CTX_start(ctx);
      A = BN_CTX_get(ctx);
      if ((RAND_status() == 0) && rsa->d != NULL && rsa->d->d != NULL)
            {
            /* if PRNG is not properly seeded, resort to secret exponent as unpredictable seed */
            RAND_add(rsa->d->d, rsa->d->dmax * sizeof rsa->d->d[0], 0);
            if (!BN_pseudo_rand_range(A,rsa->n)) goto err;
            }
      else
            {
            if (!BN_rand_range(A,rsa->n)) goto err;
            }
      if ((Ai=BN_mod_inverse(NULL,A,rsa->n,ctx)) == NULL) goto err;

      if (!rsa->meth->bn_mod_exp(A,A,rsa->e,rsa->n,ctx,rsa->_method_mod_n))
            goto err;
      ret = BN_BLINDING_new(A,Ai,rsa->n);
      BN_free(Ai);
err:
      BN_CTX_end(ctx);
      return ret;
      }

/* signing */
static int RSA_eay_private_encrypt(FIPS_RSA_SIZE_T flen, const unsigned char *from,
           unsigned char *to, RSA *rsa, int padding)
      {
      BIGNUM f,ret;
      int i,j,k,num=0,r= -1;
      unsigned char *buf=NULL;
      BN_CTX *ctx=NULL;
      int local_blinding = 0;
      BN_BLINDING *blinding = NULL;

      BN_init(&f);
      BN_init(&ret);

      if ((ctx=BN_CTX_new()) == NULL) goto err;
      num=BN_num_bytes(rsa->n);
      if ((buf=(unsigned char *)OPENSSL_malloc(num)) == NULL)
            {
            RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,ERR_R_MALLOC_FAILURE);
            goto err;
            }

      switch (padding)
            {
      case RSA_PKCS1_PADDING:
            i=RSA_padding_add_PKCS1_type_1(buf,num,from,flen);
            break;
      case RSA_NO_PADDING:
            i=RSA_padding_add_none(buf,num,from,flen);
            break;
      case RSA_SSLV23_PADDING:
      default:
            RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,RSA_R_UNKNOWN_PADDING_TYPE);
            goto err;
            }
      if (i <= 0) goto err;

      if (BN_bin2bn(buf,num,&f) == NULL) goto err;
      
      if (BN_ucmp(&f, rsa->n) >= 0)
            {     
            /* usually the padding functions would catch this */
            RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
            goto err;
            }

      BLINDING_HELPER(rsa, ctx, goto err;);
      blinding = rsa->blinding;
      
      /* Now unless blinding is disabled, 'blinding' is non-NULL.
       * But the BN_BLINDING object may be owned by some other thread
       * (we don't want to keep it constant and we don't want to use
       * lots of locking to avoid race conditions, so only a single
       * thread can use it; other threads have to use local blinding
       * factors) */
      if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
            {
            if (blinding == NULL)
                  {
                  RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, ERR_R_INTERNAL_ERROR);
                  goto err;
                  }
            }
      
      if (blinding != NULL)
            {
            if (blinding->thread_id != CRYPTO_thread_id())
                  {
                  /* we need a local one-time blinding factor */

                  blinding = setup_blinding(rsa, ctx);
                  if (blinding == NULL)
                        goto err;
                  local_blinding = 1;
                  }
            }

      if (blinding)
            if (!BN_BLINDING_convert(&f, blinding, ctx)) goto err;

      if ( (rsa->flags & RSA_FLAG_EXT_PKEY) ||
            ((rsa->p != NULL) &&
            (rsa->q != NULL) &&
            (rsa->dmp1 != NULL) &&
            (rsa->dmq1 != NULL) &&
            (rsa->iqmp != NULL)) )
            { if (!rsa->meth->rsa_mod_exp(&ret,&f,rsa)) goto err; }
      else
            {
            if (!rsa->meth->bn_mod_exp(&ret,&f,rsa->d,rsa->n,ctx,NULL)) goto err;
            }

      if (blinding)
            if (!BN_BLINDING_invert(&ret, blinding, ctx)) goto err;

      /* put in leading 0 bytes if the number is less than the
       * length of the modulus */
      j=BN_num_bytes(&ret);
      i=BN_bn2bin(&ret,&(to[num-j]));
      for (k=0; k<(num-i); k++)
            to[k]=0;

      r=num;
err:
      if (ctx != NULL) BN_CTX_free(ctx);
      BN_clear_free(&ret);
      BN_clear_free(&f);
      if (local_blinding)
            BN_BLINDING_free(blinding);
      if (buf != NULL)
            {
            OPENSSL_cleanse(buf,num);
            OPENSSL_free(buf);
            }
      return(r);
      }

static int RSA_eay_private_decrypt(FIPS_RSA_SIZE_T flen, const unsigned char *from,
           unsigned char *to, RSA *rsa, int padding)
      {
      BIGNUM f,ret;
      int j,num=0,r= -1;
      unsigned char *p;
      unsigned char *buf=NULL;
      BN_CTX *ctx=NULL;
      int local_blinding = 0;
      BN_BLINDING *blinding = NULL;

      BN_init(&f);
      BN_init(&ret);
      ctx=BN_CTX_new();
      if (ctx == NULL) goto err;

      num=BN_num_bytes(rsa->n);

      if ((buf=(unsigned char *)OPENSSL_malloc(num)) == NULL)
            {
            RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,ERR_R_MALLOC_FAILURE);
            goto err;
            }

      /* This check was for equality but PGP does evil things
       * and chops off the top '0' bytes */
      if (flen > num)
            {
            RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,RSA_R_DATA_GREATER_THAN_MOD_LEN);
            goto err;
            }

      /* make data into a big number */
      if (BN_bin2bn(from,(int)flen,&f) == NULL) goto err;

      if (BN_ucmp(&f, rsa->n) >= 0)
            {
            RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
            goto err;
            }

      BLINDING_HELPER(rsa, ctx, goto err;);
      blinding = rsa->blinding;
      
      /* Now unless blinding is disabled, 'blinding' is non-NULL.
       * But the BN_BLINDING object may be owned by some other thread
       * (we don't want to keep it constant and we don't want to use
       * lots of locking to avoid race conditions, so only a single
       * thread can use it; other threads have to use local blinding
       * factors) */
      if (!(rsa->flags & RSA_FLAG_NO_BLINDING))
            {
            if (blinding == NULL)
                  {
                  RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
                  goto err;
                  }
            }
      
      if (blinding != NULL)
            {
            if (blinding->thread_id != CRYPTO_thread_id())
                  {
                  /* we need a local one-time blinding factor */

                  blinding = setup_blinding(rsa, ctx);
                  if (blinding == NULL)
                        goto err;
                  local_blinding = 1;
                  }
            }

      if (blinding)
            if (!BN_BLINDING_convert(&f, blinding, ctx)) goto err;

      /* do the decrypt */
      if ( (rsa->flags & RSA_FLAG_EXT_PKEY) ||
            ((rsa->p != NULL) &&
            (rsa->q != NULL) &&
            (rsa->dmp1 != NULL) &&
            (rsa->dmq1 != NULL) &&
            (rsa->iqmp != NULL)) )
            { if (!rsa->meth->rsa_mod_exp(&ret,&f,rsa)) goto err; }
      else
            {
            if (!rsa->meth->bn_mod_exp(&ret,&f,rsa->d,rsa->n,ctx,NULL))
                  goto err;
            }

      if (blinding)
            if (!BN_BLINDING_invert(&ret, blinding, ctx)) goto err;

      p=buf;
      j=BN_bn2bin(&ret,p); /* j is only used with no-padding mode */

      switch (padding)
            {
      case RSA_PKCS1_PADDING:
            r=RSA_padding_check_PKCS1_type_2(to,num,buf,j,num);
            break;
#ifndef OPENSSL_NO_SHA
        case RSA_PKCS1_OAEP_PADDING:
              r=RSA_padding_check_PKCS1_OAEP(to,num,buf,j,num,NULL,0);
                break;
#endif
      case RSA_SSLV23_PADDING:
            r=RSA_padding_check_SSLv23(to,num,buf,j,num);
            break;
      case RSA_NO_PADDING:
            r=RSA_padding_check_none(to,num,buf,j,num);
            break;
      default:
            RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,RSA_R_UNKNOWN_PADDING_TYPE);
            goto err;
            }
      if (r < 0)
            RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,RSA_R_PADDING_CHECK_FAILED);

err:
      if (ctx != NULL) BN_CTX_free(ctx);
      BN_clear_free(&f);
      BN_clear_free(&ret);
      if (local_blinding)
            BN_BLINDING_free(blinding);
      if (buf != NULL)
            {
            OPENSSL_cleanse(buf,num);
            OPENSSL_free(buf);
            }
      return(r);
      }

/* signature verification */
static int RSA_eay_public_decrypt(FIPS_RSA_SIZE_T flen, const unsigned char *from,
           unsigned char *to, RSA *rsa, int padding)
      {
      BIGNUM f,ret;
      int i,num=0,r= -1;
      unsigned char *p;
      unsigned char *buf=NULL;
      BN_CTX *ctx=NULL;

      BN_init(&f);
      BN_init(&ret);
      ctx=BN_CTX_new();
      if (ctx == NULL) goto err;

      num=BN_num_bytes(rsa->n);
      buf=(unsigned char *)OPENSSL_malloc(num);
      if (buf == NULL)
            {
            RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,ERR_R_MALLOC_FAILURE);
            goto err;
            }

      /* This check was for equality but PGP does evil things
       * and chops off the top '0' bytes */
      if (flen > num)
            {
            RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,RSA_R_DATA_GREATER_THAN_MOD_LEN);
            goto err;
            }

      if (BN_bin2bn(from,flen,&f) == NULL) goto err;

      if (BN_ucmp(&f, rsa->n) >= 0)
            {
            RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
            goto err;
            }

      /* do the decrypt */
      if ((rsa->_method_mod_n == NULL) && (rsa->flags & RSA_FLAG_CACHE_PUBLIC))
            {
            BN_MONT_CTX* bn_mont_ctx;
            if ((bn_mont_ctx=BN_MONT_CTX_new()) == NULL)
                  goto err;
            if (!BN_MONT_CTX_set(bn_mont_ctx,rsa->n,ctx))
                  {
                  BN_MONT_CTX_free(bn_mont_ctx);
                  goto err;
                  }
            if (rsa->_method_mod_n == NULL) /* other thread may have finished first */
                  {
                  CRYPTO_w_lock(CRYPTO_LOCK_RSA);
                  if (rsa->_method_mod_n == NULL)
                        {
                        rsa->_method_mod_n = bn_mont_ctx;
                        bn_mont_ctx = NULL;
                        }
                  CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
                  }
            if (bn_mont_ctx)
                  BN_MONT_CTX_free(bn_mont_ctx);
            }
            
      if (!rsa->meth->bn_mod_exp(&ret,&f,rsa->e,rsa->n,ctx,
            rsa->_method_mod_n)) goto err;

      p=buf;
      i=BN_bn2bin(&ret,p);

      switch (padding)
            {
      case RSA_PKCS1_PADDING:
            r=RSA_padding_check_PKCS1_type_1(to,num,buf,i,num);
            break;
      case RSA_NO_PADDING:
            r=RSA_padding_check_none(to,num,buf,i,num);
            break;
      default:
            RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,RSA_R_UNKNOWN_PADDING_TYPE);
            goto err;
            }
      if (r < 0)
            RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,RSA_R_PADDING_CHECK_FAILED);

err:
      if (ctx != NULL) BN_CTX_free(ctx);
      BN_clear_free(&f);
      BN_clear_free(&ret);
      if (buf != NULL)
            {
            OPENSSL_cleanse(buf,num);
            OPENSSL_free(buf);
            }
      return(r);
      }

static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa)
      {
      BIGNUM r1,m1,vrfy;
      int ret=0;
      BN_CTX *ctx;

      BN_init(&m1);
      BN_init(&r1);
      BN_init(&vrfy);
      if ((ctx=BN_CTX_new()) == NULL) goto err;

      if (rsa->flags & RSA_FLAG_CACHE_PRIVATE)
            {
            if (rsa->_method_mod_p == NULL)
                  {
                  BN_MONT_CTX* bn_mont_ctx;
                  if ((bn_mont_ctx=BN_MONT_CTX_new()) == NULL)
                        goto err;
                  if (!BN_MONT_CTX_set(bn_mont_ctx,rsa->p,ctx))
                        {
                        BN_MONT_CTX_free(bn_mont_ctx);
                        goto err;
                        }
                  if (rsa->_method_mod_p == NULL) /* other thread may have finished first */
                        {
                        CRYPTO_w_lock(CRYPTO_LOCK_RSA);
                        if (rsa->_method_mod_p == NULL)
                              {
                              rsa->_method_mod_p = bn_mont_ctx;
                              bn_mont_ctx = NULL;
                              }
                        CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
                        }
                  if (bn_mont_ctx)
                        BN_MONT_CTX_free(bn_mont_ctx);
                  }

            if (rsa->_method_mod_q == NULL)
                  {
                  BN_MONT_CTX* bn_mont_ctx;
                  if ((bn_mont_ctx=BN_MONT_CTX_new()) == NULL)
                        goto err;
                  if (!BN_MONT_CTX_set(bn_mont_ctx,rsa->q,ctx))
                        {
                        BN_MONT_CTX_free(bn_mont_ctx);
                        goto err;
                        }
                  if (rsa->_method_mod_q == NULL) /* other thread may have finished first */
                        {
                        CRYPTO_w_lock(CRYPTO_LOCK_RSA);
                        if (rsa->_method_mod_q == NULL)
                              {
                              rsa->_method_mod_q = bn_mont_ctx;
                              bn_mont_ctx = NULL;
                              }
                        CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
                        }
                  if (bn_mont_ctx)
                        BN_MONT_CTX_free(bn_mont_ctx);
                  }
            }
            
      if (!BN_mod(&r1,I,rsa->q,ctx)) goto err;
      if (!rsa->meth->bn_mod_exp(&m1,&r1,rsa->dmq1,rsa->q,ctx,
            rsa->_method_mod_q)) goto err;

      if (!BN_mod(&r1,I,rsa->p,ctx)) goto err;
      if (!rsa->meth->bn_mod_exp(r0,&r1,rsa->dmp1,rsa->p,ctx,
            rsa->_method_mod_p)) goto err;

      if (!BN_sub(r0,r0,&m1)) goto err;
      /* This will help stop the size of r0 increasing, which does
       * affect the multiply if it optimised for a power of 2 size */
      if (r0->neg)
            if (!BN_add(r0,r0,rsa->p)) goto err;

      if (!BN_mul(&r1,r0,rsa->iqmp,ctx)) goto err;
      if (!BN_mod(r0,&r1,rsa->p,ctx)) goto err;
      /* If p < q it is occasionally possible for the correction of
         * adding 'p' if r0 is negative above to leave the result still
       * negative. This can break the private key operations: the following
       * second correction should *always* correct this rare occurrence.
       * This will *never* happen with OpenSSL generated keys because
         * they ensure p > q [steve]
         */
      if (r0->neg)
            if (!BN_add(r0,r0,rsa->p)) goto err;
      if (!BN_mul(&r1,r0,rsa->q,ctx)) goto err;
      if (!BN_add(r0,&r1,&m1)) goto err;

      if (rsa->e && rsa->n)
            {
            if (!rsa->meth->bn_mod_exp(&vrfy,r0,rsa->e,rsa->n,ctx,NULL)) goto err;
            /* If 'I' was greater than (or equal to) rsa->n, the operation
             * will be equivalent to using 'I mod n'. However, the result of
             * the verify will *always* be less than 'n' so we don't check
             * for absolute equality, just congruency. */
            if (!BN_sub(&vrfy, &vrfy, I)) goto err;
            if (!BN_mod(&vrfy, &vrfy, rsa->n, ctx)) goto err;
            if (vrfy.neg)
                  if (!BN_add(&vrfy, &vrfy, rsa->n)) goto err;
            if (!BN_is_zero(&vrfy))
                  /* 'I' and 'vrfy' aren't congruent mod n. Don't leak
                   * miscalculated CRT output, just do a raw (slower)
                   * mod_exp and return that instead. */
                  if (!rsa->meth->bn_mod_exp(r0,I,rsa->d,rsa->n,ctx,NULL)) goto err;
            }
      ret=1;
err:
      BN_clear_free(&m1);
      BN_clear_free(&r1);
      BN_clear_free(&vrfy);
      BN_CTX_free(ctx);
      return(ret);
      }

static int RSA_eay_init(RSA *rsa)
      {
      rsa->flags|=RSA_FLAG_CACHE_PUBLIC|RSA_FLAG_CACHE_PRIVATE;
      return(1);
      }

static int RSA_eay_finish(RSA *rsa)
      {
      if (rsa->_method_mod_n != NULL)
            BN_MONT_CTX_free(rsa->_method_mod_n);
      if (rsa->_method_mod_p != NULL)
            BN_MONT_CTX_free(rsa->_method_mod_p);
      if (rsa->_method_mod_q != NULL)
            BN_MONT_CTX_free(rsa->_method_mod_q);
      return(1);
      }

#endif

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