Import OpenSSL 0.9.8h.

[dragonfly.git] / crypto / openssl-0.9 / crypto / rsa / 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.]
 */
/* ====================================================================
 * 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"
#include <openssl/bn.h>
#include <openssl/rsa.h>
#include <openssl/rand.h>

#ifndef RSA_NULL

static int RSA_eay_public_encrypt(int flen, const unsigned char *from,
                unsigned char *to, RSA *rsa,int padding);
static int RSA_eay_private_encrypt(int flen, const unsigned char *from,
                unsigned char *to, RSA *rsa,int padding);
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, BN_CTX *ctx);
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 */
        NULL /* rsa_keygen */
        };

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

/* Usage example;
 *    MONT_HELPER(rsa->_method_mod_p, bn_ctx, rsa->p, rsa->flags & RSA_FLAG_CACHE_PRIVATE, goto err);
 */
#define MONT_HELPER(method_mod, ctx, m, pre_cond, err_instr) \
        if ((pre_cond) && ((method_mod) == NULL) && \
                        !BN_MONT_CTX_set_locked(&(method_mod), \
                                CRYPTO_LOCK_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;
        int i,j,k,num=0,r= -1;
        unsigned char *buf=NULL;
        BN_CTX *ctx=NULL;

        if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS)
                {
                RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_MODULUS_TOO_LARGE);
                return -1;
                }

        if (BN_ucmp(rsa->n, rsa->e) <= 0)
                {
                RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
                return -1;
                }

        /* for large moduli, enforce exponent limit */
        if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS)
                {
                if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS)
                        {
                        RSAerr(RSA_F_RSA_EAY_PUBLIC_ENCRYPT, RSA_R_BAD_E_VALUE);
                        return -1;
                        }
                }
        
        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 = OPENSSL_malloc(num);
        if (!f || !ret || !buf)
                {
                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;
                }

        MONT_HELPER(rsa->_method_mod_n, ctx, rsa->n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err);

        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_end(ctx);
                BN_CTX_free(ctx);
                }
        if (buf != NULL) 
                {
                OPENSSL_cleanse(buf,num);
                OPENSSL_free(buf);
                }
        return(r);
        }

static BN_BLINDING *rsa_get_blinding(RSA *rsa, int *local, BN_CTX *ctx)
{
        BN_BLINDING *ret;
        int got_write_lock = 0;

        CRYPTO_r_lock(CRYPTO_LOCK_RSA);

        if (rsa->blinding == NULL)
                {
                CRYPTO_r_unlock(CRYPTO_LOCK_RSA);
                CRYPTO_w_lock(CRYPTO_LOCK_RSA);
                got_write_lock = 1;

                if (rsa->blinding == NULL)
                        rsa->blinding = RSA_setup_blinding(rsa, ctx);
                }

        ret = rsa->blinding;
        if (ret == NULL)
                goto err;

        if (BN_BLINDING_get_thread_id(ret) == CRYPTO_thread_id())
                {
                /* rsa->blinding is ours! */

                *local = 1;
                }
        else
                {
                /* 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;
                }

 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, *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;

        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_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_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;
        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;
                }

        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);
                        goto err;
                        }
                }
        
        if (blinding != NULL)
                if (!rsa_blinding_convert(blinding, local_blinding, f, br, 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, ctx)) goto err;
                }
        else
                {
                BIGNUM local_d;
                BIGNUM *d = NULL;
                
                if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
                        {
                        BN_init(&local_d);
                        d = &local_d;
                        BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
                        }
                else
                        d= rsa->d;

                MONT_HELPER(rsa->_method_mod_n, ctx, rsa->n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err);

                if (!rsa->meth->bn_mod_exp(ret,f,d,rsa->n,ctx,
                                rsa->_method_mod_n)) goto err;
                }

        if (blinding)
                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(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_end(ctx);
                BN_CTX_free(ctx);
                }
        if (buf != NULL)
                {
                OPENSSL_cleanse(buf,num);
                OPENSSL_free(buf);
                }
        return(r);
        }

static int RSA_eay_private_decrypt(int flen, const unsigned char *from,
             unsigned char *to, RSA *rsa, int padding)
        {
        BIGNUM *f, *ret, *br;
        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;

        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;
                }

        /* 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;
                }

        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);
                        goto err;
                        }
                }
        
        if (blinding != NULL)
                if (!rsa_blinding_convert(blinding, local_blinding, f, br, 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, ctx)) goto err;
                }
        else
                {
                BIGNUM local_d;
                BIGNUM *d = NULL;
                
                if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
                        {
                        d = &local_d;
                        BN_with_flags(d, rsa->d, BN_FLG_CONSTTIME);
                        }
                else
                        d = rsa->d;

                MONT_HELPER(rsa->_method_mod_n, ctx, rsa->n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err);
                if (!rsa->meth->bn_mod_exp(ret,f,d,rsa->n,ctx,
                                rsa->_method_mod_n))
                  goto err;
                }

        if (blinding)
                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 */

        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_end(ctx);
                BN_CTX_free(ctx);
                }
        if (buf != NULL)
                {
                OPENSSL_cleanse(buf,num);
                OPENSSL_free(buf);
                }
        return(r);
        }

/* signature verification */
static int RSA_eay_public_decrypt(int 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;

        if (BN_num_bits(rsa->n) > OPENSSL_RSA_MAX_MODULUS_BITS)
                {
                RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_MODULUS_TOO_LARGE);
                return -1;
                }

        if (BN_ucmp(rsa->n, rsa->e) <= 0)
                {
                RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
                return -1;
                }

        /* for large moduli, enforce exponent limit */
        if (BN_num_bits(rsa->n) > OPENSSL_RSA_SMALL_MODULUS_BITS)
                {
                if (BN_num_bits(rsa->e) > OPENSSL_RSA_MAX_PUBEXP_BITS)
                        {
                        RSAerr(RSA_F_RSA_EAY_PUBLIC_DECRYPT, RSA_R_BAD_E_VALUE);
                        return -1;
                        }
                }
        
        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 = OPENSSL_malloc(num);
        if(!f || !ret || !buf)
                {
                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;
                }

        MONT_HELPER(rsa->_method_mod_n, ctx, rsa->n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err);

        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);

        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;
        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_end(ctx);
                BN_CTX_free(ctx);
                }
        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, BN_CTX *ctx)
        {
        BIGNUM *r1,*m1,*vrfy;
        BIGNUM local_dmp1,local_dmq1,local_c,local_r1;
        BIGNUM *dmp1,*dmq1,*c,*pr1;
        int ret=0;

        BN_CTX_start(ctx);
        r1 = BN_CTX_get(ctx);
        m1 = BN_CTX_get(ctx);
        vrfy = BN_CTX_get(ctx);

        {
                BIGNUM local_p, local_q;
                BIGNUM *p = NULL, *q = NULL;

                /* Make sure BN_mod_inverse in Montgomery intialization uses the
                 * BN_FLG_CONSTTIME flag (unless RSA_FLAG_NO_CONSTTIME is set)
                 */
                if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
                        {
                        BN_init(&local_p);
                        p = &local_p;
                        BN_with_flags(p, rsa->p, BN_FLG_CONSTTIME);

                        BN_init(&local_q);
                        q = &local_q;
                        BN_with_flags(q, rsa->q, BN_FLG_CONSTTIME);
                        }
                else
                        {
                        p = rsa->p;
                        q = rsa->q;
                        }

                MONT_HELPER(rsa->_method_mod_p, ctx, p, rsa->flags & RSA_FLAG_CACHE_PRIVATE, goto err);
                MONT_HELPER(rsa->_method_mod_q, ctx, q, rsa->flags & RSA_FLAG_CACHE_PRIVATE, goto err);
        }

        MONT_HELPER(rsa->_method_mod_n, ctx, rsa->n, rsa->flags & RSA_FLAG_CACHE_PUBLIC, goto err);

        /* compute I mod q */
        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
                {
                c = &local_c;
                BN_with_flags(c, I, BN_FLG_CONSTTIME);
                if (!BN_mod(r1,c,rsa->q,ctx)) goto err;
                }
        else
                {
                if (!BN_mod(r1,I,rsa->q,ctx)) goto err;
                }

        /* compute r1^dmq1 mod q */
        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
                {
                dmq1 = &local_dmq1;
                BN_with_flags(dmq1, rsa->dmq1, BN_FLG_CONSTTIME);
                }
        else
                dmq1 = rsa->dmq1;
        if (!rsa->meth->bn_mod_exp(m1,r1,dmq1,rsa->q,ctx,
                rsa->_method_mod_q)) goto err;

        /* compute I mod p */
        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
                {
                c = &local_c;
                BN_with_flags(c, I, BN_FLG_CONSTTIME);
                if (!BN_mod(r1,c,rsa->p,ctx)) goto err;
                }
        else
                {
                if (!BN_mod(r1,I,rsa->p,ctx)) goto err;
                }

        /* compute r1^dmp1 mod p */
        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
                {
                dmp1 = &local_dmp1;
                BN_with_flags(dmp1, rsa->dmp1, BN_FLG_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;
        /* 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_is_negative(r0))
                if (!BN_add(r0,r0,rsa->p)) goto err;

        if (!BN_mul(r1,r0,rsa->iqmp,ctx)) goto err;

        /* Turn BN_FLG_CONSTTIME flag on before division operation */
        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
                {
                pr1 = &local_r1;
                BN_with_flags(pr1, r1, BN_FLG_CONSTTIME);
                }
        else
                pr1 = r1;
        if (!BN_mod(r0,pr1,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 (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 (rsa->e && rsa->n)
                {
                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_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. */

                        BIGNUM local_d;
                        BIGNUM *d = NULL;
                
                        if (!(rsa->flags & RSA_FLAG_NO_CONSTTIME))
                                {
                                d = &local_d;
                                BN_with_flags(d, rsa->d, BN_FLG_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_CTX_end(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