New functions CRYPTO_set_idptr_callback(),
[openssl.git] / crypto / rsa / rsa_eay.c
index aff86343ccefcd54ad7e63af0b1ae842258da327..c6ceaee6e731689448c0d9c1ab35a43b2887b929 100644 (file)
  * copied and put under another distribution licence
  * [including the GNU Public Licence.]
  */
+/* ====================================================================
+ * Copyright (c) 1998-2006 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
+ *    openssl-core@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"
@@ -72,7 +125,7 @@ static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
                unsigned char *to, RSA *rsa,int padding);
 static int RSA_eay_private_decrypt(int 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_mod_exp(BIGNUM *r0, const BIGNUM *i, RSA *rsa, BN_CTX *ctx);
 static int RSA_eay_init(RSA *rsa);
 static int RSA_eay_finish(RSA *rsa);
 static RSA_METHOD rsa_pkcs1_eay_meth={
@@ -97,56 +150,31 @@ const RSA_METHOD *RSA_PKCS1_SSLeay(void)
        return(&rsa_pkcs1_eay_meth);
        }
 
-/* Static helper to reduce oodles of code duplication. As a slight
- * optimisation, the "MONT_HELPER() macro must be used as front-end to this
- * function, to prevent unnecessary function calls - there is an initial test
- * that is performed by the macro-generated code. */
-static int rsa_eay_mont_helper(BN_MONT_CTX **ptr, const BIGNUM *modulus, BN_CTX *ctx)
-       {
-       BN_MONT_CTX *bn_mont_ctx;
-       if((bn_mont_ctx = BN_MONT_CTX_new()) == NULL)
-               return 0;
-       if(!BN_MONT_CTX_set(bn_mont_ctx, modulus, ctx))
-               {
-               BN_MONT_CTX_free(bn_mont_ctx);
-               return 0;
-               }
-       if (*ptr == NULL) /* other thread may have finished first */
-               {
-               CRYPTO_w_lock(CRYPTO_LOCK_RSA);
-               if (*ptr == NULL) /* check again in the lock to stop races */
-                       {
-                       *ptr = bn_mont_ctx;
-                       bn_mont_ctx = NULL;
-                       }
-               CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
-               }
-       if (bn_mont_ctx)
-               BN_MONT_CTX_free(bn_mont_ctx);
-       return 1;
-       }
 /* Usage example;
  *    MONT_HELPER(rsa, bn_ctx, p, rsa->flags & RSA_FLAG_CACHE_PRIVATE, goto err);
  */
 #define MONT_HELPER(rsa, ctx, m, pre_cond, err_instr) \
        if((pre_cond) && ((rsa)->_method_mod_##m == NULL) && \
-                       !rsa_eay_mont_helper(&((rsa)->_method_mod_##m), \
+                       !BN_MONT_CTX_set_locked(&((rsa)->_method_mod_##m), \
+                               CRYPTO_LOCK_RSA, \
                                (rsa)->m, (ctx))) \
                err_instr
 
 static int RSA_eay_public_encrypt(int flen, const unsigned char *from,
             unsigned char *to, RSA *rsa, int padding)
        {
-       BIGNUM f,ret;
+       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 ((ctx=BN_CTX_new()) == NULL) goto err;
+       BN_CTX_start(ctx);
+       f = BN_CTX_get(ctx);
+       ret = BN_CTX_get(ctx);
        num=BN_num_bytes(rsa->n);
-       if ((buf=(unsigned char *)OPENSSL_malloc(num)) == NULL)
+       buf = OPENSSL_malloc(num);
+       if (!f || !ret || !buf)
                {
                RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT,ERR_R_MALLOC_FAILURE);
                goto err;
@@ -174,9 +202,9 @@ static int RSA_eay_public_encrypt(int flen, const unsigned char *from,
                }
        if (i <= 0) goto err;
 
-       if (BN_bin2bn(buf,num,&f) == NULL) goto err;
+       if (BN_bin2bn(buf,num,f) == NULL) goto err;
        
-       if (BN_ucmp(&f, rsa->n) >= 0)
+       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);
@@ -185,21 +213,23 @@ static int RSA_eay_public_encrypt(int flen, const unsigned char *from,
 
        MONT_HELPER(rsa, ctx, n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err);
 
-       if (!rsa->meth->bn_mod_exp(&ret,&f,rsa->e,rsa->n,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]));
+       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 (ctx != NULL)
+               {
+               BN_CTX_end(ctx);
+               BN_CTX_free(ctx);
+               }
        if (buf != NULL) 
                {
                OPENSSL_cleanse(buf,num);
@@ -208,76 +238,115 @@ err:
        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;
-       }
+static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
+{
+       BN_BLINDING *ret;
+       int got_write_lock = 0;
 
-#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)
+       CRYPTO_r_lock(CRYPTO_LOCK_RSA);
 
-static BN_BLINDING *setup_blinding(RSA *rsa, BN_CTX *ctx)
-       {
-       BIGNUM *A, *Ai;
-       BN_BLINDING *ret = NULL;
+       if (rsa->blinding == NULL)
+               {
+               CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
+               CRYPTO_w_lock(CRYPTO_LOCK_RSA);
+               got_write_lock = 1;
 
-       /* added in OpenSSL 0.9.6j and 0.9.7b */
+               if (rsa->blinding == NULL)
+                       rsa->blinding = RSA_setup_blinding(rsa, ctx);
+               }
 
-       /* 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 */
+       ret = rsa->blinding;
+       if (ret == NULL)
+               goto err;
 
-       BN_CTX_start(ctx);
-       A = BN_CTX_get(ctx);
-       if ((RAND_status() == 0) && rsa->d != NULL && rsa->d->d != NULL)
+       if ((BN_BLINDING_get_thread_id(ret) == CRYPTO_thread_id()) && (BN_BLINDING_get_thread_idptr(ret) == CRYPTO_thread_idptr()))
                {
-               /* 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;
+               /* rsa->blinding is ours! */
+
+               *local = 1;
                }
        else
                {
-               if (!BN_rand_range(A,rsa->n)) goto err;
+               /* resort to rsa->mt_blinding instead */
+
+               *local = 0; /* instructs rsa_blinding_convert(), rsa_blinding_invert()
+                            * that the BN_BLINDING is shared, meaning that accesses
+                            * require locks, and that the blinding factor must be
+                            * stored outside the BN_BLINDING
+                            */
+
+               if (rsa->mt_blinding == NULL)
+                       {
+                       if (!got_write_lock)
+                               {
+                               CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
+                               CRYPTO_w_lock(CRYPTO_LOCK_RSA);
+                               got_write_lock = 1;
+                               }
+                       
+                       if (rsa->mt_blinding == NULL)
+                               rsa->mt_blinding = RSA_setup_blinding(rsa, ctx);
+                       }
+               ret = rsa->mt_blinding;
                }
-       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);
+ err:
+       if (got_write_lock)
+               CRYPTO_w_unlock(CRYPTO_LOCK_RSA);
+       else
+               CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
        return ret;
-       }
+}
+
+static int rsa_blinding_convert(BN_BLINDING *b, int local, BIGNUM *f,
+       BIGNUM *r, BN_CTX *ctx)
+{
+       if (local)
+               return BN_BLINDING_convert_ex(f, NULL, b, ctx);
+       else
+               {
+               int ret;
+               CRYPTO_r_lock(CRYPTO_LOCK_RSA_BLINDING);
+               ret = BN_BLINDING_convert_ex(f, r, b, ctx);
+               CRYPTO_r_unlock(CRYPTO_LOCK_RSA_BLINDING);
+               return ret;
+               }
+}
+
+static int rsa_blinding_invert(BN_BLINDING *b, int local, BIGNUM *f,
+       BIGNUM *r, BN_CTX *ctx)
+{
+       if (local)
+               return BN_BLINDING_invert_ex(f, NULL, b, ctx);
+       else
+               {
+               int ret;
+               CRYPTO_w_lock(CRYPTO_LOCK_RSA_BLINDING);
+               ret = BN_BLINDING_invert_ex(f, r, b, ctx);
+               CRYPTO_w_unlock(CRYPTO_LOCK_RSA_BLINDING);
+               return ret;
+               }
+}
 
 /* signing */
 static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
             unsigned char *to, RSA *rsa, int padding)
        {
-       BIGNUM f,ret;
+       BIGNUM *f, *ret, *br, *res;
        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)
+       BN_CTX_start(ctx);
+       f   = BN_CTX_get(ctx);
+       br  = BN_CTX_get(ctx);
+       ret = BN_CTX_get(ctx);
+       num = BN_num_bytes(rsa->n);
+       buf = OPENSSL_malloc(num);
+       if(!f || !ret || !buf)
                {
                RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT,ERR_R_MALLOC_FAILURE);
                goto err;
@@ -288,6 +357,9 @@ static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
        case RSA_PKCS1_PADDING:
                i=RSA_padding_add_PKCS1_type_1(buf,num,from,flen);
                break;
+       case RSA_X931_PADDING:
+               i=RSA_padding_add_X931(buf,num,from,flen);
+               break;
        case RSA_NO_PADDING:
                i=RSA_padding_add_none(buf,num,from,flen);
                break;
@@ -298,26 +370,18 @@ static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
                }
        if (i <= 0) goto err;
 
-       if (BN_bin2bn(buf,num,&f) == NULL) goto err;
+       if (BN_bin2bn(buf,num,f) == NULL) goto err;
        
-       if (BN_ucmp(&f, rsa->n) >= 0)
+       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))
                {
+               blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
                if (blinding == NULL)
                        {
                        RSAerr(RSA_F_RSA_EAY_PRIVATE_ENCRYPT, ERR_R_INTERNAL_ERROR);
@@ -326,20 +390,8 @@ static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
                }
        
        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_blinding_convert(blinding, local_blinding, f, br, ctx))
+                       goto err;
 
        if ( (rsa->flags & RSA_FLAG_EXT_PKEY) ||
                ((rsa->p != NULL) &&
@@ -347,31 +399,58 @@ static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
                (rsa->dmp1 != NULL) &&
                (rsa->dmq1 != NULL) &&
                (rsa->iqmp != NULL)) )
-               { if (!rsa->meth->rsa_mod_exp(&ret,&f,rsa)) goto err; }
+               { 
+               if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx)) goto err;
+               }
        else
                {
+               BIGNUM local_d;
+               BIGNUM *d = NULL;
+               
+               if (!(rsa->flags & RSA_FLAG_NO_EXP_CONSTTIME))
+                       {
+                       BN_init(&local_d);
+                       d = &local_d;
+                       BN_with_flags(d, rsa->d, BN_FLG_EXP_CONSTTIME);
+                       }
+               else
+                       d = rsa->d;
+
                MONT_HELPER(rsa, ctx, n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err);
-               if (!rsa->meth->bn_mod_exp(&ret,&f,rsa->d,rsa->n,ctx,
+
+               if (!rsa->meth->bn_mod_exp(ret,f,d,rsa->n,ctx,
                                rsa->_method_mod_n)) goto err;
                }
 
        if (blinding)
-               if (!BN_BLINDING_invert(&ret, blinding, ctx)) goto err;
+               if (!rsa_blinding_invert(blinding, local_blinding, ret, br, ctx))
+                       goto err;
+
+       if (padding == RSA_X931_PADDING)
+               {
+               BN_sub(f, rsa->n, ret);
+               if (BN_cmp(ret, f))
+                       res = f;
+               else
+                       res = ret;
+               }
+       else
+               res = ret;
 
        /* 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]));
+       j=BN_num_bytes(res);
+       i=BN_bn2bin(res,&(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 (ctx != NULL)
+               {
+               BN_CTX_end(ctx);
+               BN_CTX_free(ctx);
+               }
        if (buf != NULL)
                {
                OPENSSL_cleanse(buf,num);
@@ -383,7 +462,7 @@ err:
 static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
             unsigned char *to, RSA *rsa, int padding)
        {
-       BIGNUM f,ret;
+       BIGNUM *f, *ret, *br;
        int j,num=0,r= -1;
        unsigned char *p;
        unsigned char *buf=NULL;
@@ -391,14 +470,14 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
        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)
+       if((ctx = BN_CTX_new()) == NULL) goto err;
+       BN_CTX_start(ctx);
+       f   = BN_CTX_get(ctx);
+       br  = BN_CTX_get(ctx);
+       ret = BN_CTX_get(ctx);
+       num = BN_num_bytes(rsa->n);
+       buf = OPENSSL_malloc(num);
+       if(!f || !ret || !buf)
                {
                RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT,ERR_R_MALLOC_FAILURE);
                goto err;
@@ -413,25 +492,17 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
                }
 
        /* make data into a big number */
-       if (BN_bin2bn(from,(int)flen,&f) == NULL) goto err;
+       if (BN_bin2bn(from,(int)flen,f) == NULL) goto err;
 
-       if (BN_ucmp(&f, rsa->n) >= 0)
+       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))
                {
+               blinding = rsa_get_blinding(rsa, &local_blinding, ctx);
                if (blinding == NULL)
                        {
                        RSAerr(RSA_F_RSA_EAY_PRIVATE_DECRYPT, ERR_R_INTERNAL_ERROR);
@@ -440,20 +511,8 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
                }
        
        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_blinding_convert(blinding, local_blinding, f, br, ctx))
+                       goto err;
 
        /* do the decrypt */
        if ( (rsa->flags & RSA_FLAG_EXT_PKEY) ||
@@ -462,20 +521,34 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
                (rsa->dmp1 != NULL) &&
                (rsa->dmq1 != NULL) &&
                (rsa->iqmp != NULL)) )
-               { if (!rsa->meth->rsa_mod_exp(&ret,&f,rsa)) goto err; }
+               {
+               if (!rsa->meth->rsa_mod_exp(ret, f, rsa, ctx)) goto err;
+               }
        else
                {
+               BIGNUM local_d;
+               BIGNUM *d = NULL;
+               
+               if (!(rsa->flags & RSA_FLAG_NO_EXP_CONSTTIME))
+                       {
+                       d = &local_d;
+                       BN_with_flags(d, rsa->d, BN_FLG_EXP_CONSTTIME);
+                       }
+               else
+                       d = rsa->d;
+
                MONT_HELPER(rsa, ctx, n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err);
-               if (!rsa->meth->bn_mod_exp(&ret,&f,rsa->d,rsa->n,ctx,
+               if (!rsa->meth->bn_mod_exp(ret,f,d,rsa->n,ctx,
                                rsa->_method_mod_n))
-                       goto err;
+                 goto err;
                }
 
        if (blinding)
-               if (!BN_BLINDING_invert(&ret, blinding, ctx)) goto err;
+               if (!rsa_blinding_invert(blinding, local_blinding, ret, br, ctx))
+                       goto err;
 
        p=buf;
-       j=BN_bn2bin(&ret,p); /* j is only used with no-padding mode */
+       j=BN_bn2bin(ret,p); /* j is only used with no-padding mode */
 
        switch (padding)
                {
@@ -501,9 +574,11 @@ static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
                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 (ctx != NULL)
+               {
+               BN_CTX_end(ctx);
+               BN_CTX_free(ctx);
+               }
        if (buf != NULL)
                {
                OPENSSL_cleanse(buf,num);
@@ -516,20 +591,19 @@ err:
 static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
             unsigned char *to, RSA *rsa, int padding)
        {
-       BIGNUM f,ret;
+       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;
-
+       if((ctx = BN_CTX_new()) == NULL) goto err;
+       BN_CTX_start(ctx);
+       f = BN_CTX_get(ctx);
+       ret = BN_CTX_get(ctx);
        num=BN_num_bytes(rsa->n);
-       buf=(unsigned char *)OPENSSL_malloc(num);
-       if (buf == NULL)
+       buf = OPENSSL_malloc(num);
+       if(!f || !ret || !buf)
                {
                RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,ERR_R_MALLOC_FAILURE);
                goto err;
@@ -543,9 +617,9 @@ static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
                goto err;
                }
 
-       if (BN_bin2bn(from,flen,&f) == NULL) goto err;
+       if (BN_bin2bn(from,flen,f) == NULL) goto err;
 
-       if (BN_ucmp(&f, rsa->n) >= 0)
+       if (BN_ucmp(f, rsa->n) >= 0)
                {
                RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT,RSA_R_DATA_TOO_LARGE_FOR_MODULUS);
                goto err;
@@ -553,17 +627,23 @@ static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
 
        MONT_HELPER(rsa, ctx, n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err);
 
-       if (!rsa->meth->bn_mod_exp(&ret,&f,rsa->e,rsa->n,ctx,
+       if (!rsa->meth->bn_mod_exp(ret,f,rsa->e,rsa->n,ctx,
                rsa->_method_mod_n)) goto err;
 
+       if ((padding == RSA_X931_PADDING) && ((ret->d[0] & 0xf) != 12))
+               BN_sub(ret, rsa->n, ret);
+
        p=buf;
-       i=BN_bn2bin(&ret,p);
+       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_X931_PADDING:
+               r=RSA_padding_check_X931(to,num,buf,i,num);
+               break;
        case RSA_NO_PADDING:
                r=RSA_padding_check_none(to,num,buf,i,num);
                break;
@@ -575,9 +655,11 @@ static int RSA_eay_public_decrypt(int flen, const unsigned char *from,
                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 (ctx != NULL)
+               {
+               BN_CTX_end(ctx);
+               BN_CTX_free(ctx);
+               }
        if (buf != NULL)
                {
                OPENSSL_cleanse(buf,num);
@@ -586,37 +668,52 @@ err:
        return(r);
        }
 
-static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa)
+static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa, BN_CTX *ctx)
        {
-       BIGNUM r1,m1,vrfy;
+       BIGNUM *r1,*m1,*vrfy;
+       BIGNUM local_dmp1, local_dmq1;
+       BIGNUM *dmp1, *dmq1;
        int ret=0;
-       BN_CTX *ctx;
 
-       BN_init(&m1);
-       BN_init(&r1);
-       BN_init(&vrfy);
-       if ((ctx=BN_CTX_new()) == NULL) goto err;
+       BN_CTX_start(ctx);
+       r1 = BN_CTX_get(ctx);
+       m1 = BN_CTX_get(ctx);
+       vrfy = BN_CTX_get(ctx);
 
        MONT_HELPER(rsa, ctx, p, rsa->flags & RSA_FLAG_CACHE_PRIVATE, goto err);
        MONT_HELPER(rsa, ctx, q, rsa->flags & RSA_FLAG_CACHE_PRIVATE, goto err);
        MONT_HELPER(rsa, ctx, n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err);
 
-       if (!BN_mod(&r1,I,rsa->q,ctx)) goto err;
-       if (!rsa->meth->bn_mod_exp(&m1,&r1,rsa->dmq1,rsa->q,ctx,
+       if (!BN_mod(r1,I,rsa->q,ctx)) goto err;
+       if (!(rsa->flags & RSA_FLAG_NO_EXP_CONSTTIME))
+               {
+               dmq1 = &local_dmq1;
+               BN_with_flags(dmq1, rsa->dmq1, BN_FLG_EXP_CONSTTIME);
+               }
+       else
+               dmq1 = rsa->dmq1;
+       if (!rsa->meth->bn_mod_exp(m1,r1,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,
+       if (!BN_mod(r1,I,rsa->p,ctx)) goto err;
+       if (!(rsa->flags & RSA_FLAG_NO_EXP_CONSTTIME))
+               {
+               dmp1 = &local_dmp1;
+               BN_with_flags(dmp1, rsa->dmp1, BN_FLG_EXP_CONSTTIME);
+               }
+       else
+               dmp1 = rsa->dmp1;
+       if (!rsa->meth->bn_mod_exp(r0,r1,dmp1,rsa->p,ctx,
                rsa->_method_mod_p)) goto err;
 
-       if (!BN_sub(r0,r0,&m1)) 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 (BN_get_sign(r0))
+       if (BN_is_negative(r0))
                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 (!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
@@ -624,35 +721,45 @@ static int RSA_eay_mod_exp(BIGNUM *r0, const BIGNUM *I, RSA *rsa)
         * This will *never* happen with OpenSSL generated keys because
          * they ensure p > q [steve]
          */
-       if (BN_get_sign(r0))
+       if (BN_is_negative(r0))
                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 (!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,rsa->_method_mod_n)) goto err;
+               if (!rsa->meth->bn_mod_exp(vrfy,r0,rsa->e,rsa->n,ctx,rsa->_method_mod_n)) 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 (BN_get_sign(&vrfy))
-                       if (!BN_add(&vrfy, &vrfy, rsa->n)) goto err;
-               if (!BN_is_zero(&vrfy))
+               if (!BN_sub(vrfy, vrfy, I)) goto err;
+               if (!BN_mod(vrfy, vrfy, rsa->n, ctx)) goto err;
+               if (BN_is_negative(vrfy))
+                       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,
-                                       rsa->_method_mod_n)) goto err;
+
+                       BIGNUM local_d;
+                       BIGNUM *d = NULL;
+               
+                       if (!(rsa->flags & RSA_FLAG_NO_EXP_CONSTTIME))
+                               {
+                               d = &local_d;
+                               BN_with_flags(d, rsa->d, BN_FLG_EXP_CONSTTIME);
+                               }
+                       else
+                               d = rsa->d;
+                       if (!rsa->meth->bn_mod_exp(r0,I,d,rsa->n,ctx,
+                                                  rsa->_method_mod_n)) goto err;
+                       }
                }
        ret=1;
 err:
-       BN_clear_free(&m1);
-       BN_clear_free(&r1);
-       BN_clear_free(&vrfy);
-       BN_CTX_free(ctx);
+       BN_CTX_end(ctx);
        return(ret);
        }