bn_blind.c

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/* crypto/bn/bn_blind.c */
/* ====================================================================
 * 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
 *    [email protected].
 *
 * 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
 * ([email protected]).  This product includes software written by Tim
 * Hudson ([email protected]).
 *
 */
/* Copyright (C) 1995-1998 Eric Young ([email protected])
 * All rights reserved.
 *
 * This package is an SSL implementation written
 * by Eric Young ([email protected]).
 * 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 ([email protected]).
 * 
 * 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 ([email protected])"
 *    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 ([email protected])"
 * 
 * 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 "cryptlib.h"
#include "bn_lcl.h"

#define BN_BLINDING_COUNTER 32

struct bn_blinding_st
    {
    BIGNUM *A;
    BIGNUM *Ai;
    BIGNUM *e;
    BIGNUM *mod; /* just a reference */
#ifndef OPENSSL_NO_DEPRECATED
    unsigned long thread_id; /* added in OpenSSL 0.9.6j and 0.9.7b;
                  * used only by crypto/rsa/rsa_eay.c, rsa_lib.c */
#endif
    CRYPTO_THREADID tid;
    int counter;
    unsigned long flags;
    BN_MONT_CTX *m_ctx;
    int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
              const BIGNUM *m, BN_CTX *ctx,
              BN_MONT_CTX *m_ctx);
    };

BN_BLINDING *BN_BLINDING_new(const BIGNUM *A, const BIGNUM *Ai, BIGNUM *mod)
    {
    BN_BLINDING *ret=NULL;

    bn_check_top(mod);

    if ((ret=(BN_BLINDING *)OPENSSL_malloc(sizeof(BN_BLINDING))) == NULL)
        {
        BNerr(BN_F_BN_BLINDING_NEW,ERR_R_MALLOC_FAILURE);
        return(NULL);
        }
    memset(ret,0,sizeof(BN_BLINDING));
    if (A != NULL)
        {
        if ((ret->A  = BN_dup(A))  == NULL) goto err;
        }
    if (Ai != NULL)
        {
        if ((ret->Ai = BN_dup(Ai)) == NULL) goto err;
        }

    /* save a copy of mod in the BN_BLINDING structure */
    if ((ret->mod = BN_dup(mod)) == NULL) goto err;
    if (BN_get_flags(mod, BN_FLG_CONSTTIME) != 0)
        BN_set_flags(ret->mod, BN_FLG_CONSTTIME);

    /* Set the counter to the special value -1
     * to indicate that this is never-used fresh blinding
     * that does not need updating before first use. */
    ret->counter = -1;
    CRYPTO_THREADID_current(&ret->tid);
    return(ret);
err:
    if (ret != NULL) BN_BLINDING_free(ret);
    return(NULL);
    }

void BN_BLINDING_free(BN_BLINDING *r)
    {
    if(r == NULL)
        return;

    if (r->A  != NULL) BN_free(r->A );
    if (r->Ai != NULL) BN_free(r->Ai);
    if (r->e  != NULL) BN_free(r->e );
    if (r->mod != NULL) BN_free(r->mod); 
    OPENSSL_free(r);
    }

int BN_BLINDING_update(BN_BLINDING *b, BN_CTX *ctx)
    {
    int ret=0;

    if ((b->A == NULL) || (b->Ai == NULL))
        {
        BNerr(BN_F_BN_BLINDING_UPDATE,BN_R_NOT_INITIALIZED);
        goto err;
        }

    if (b->counter == -1)
        b->counter = 0;

    if (++b->counter == BN_BLINDING_COUNTER && b->e != NULL &&
        !(b->flags & BN_BLINDING_NO_RECREATE))
        {
        /* re-create blinding parameters */
        if (!BN_BLINDING_create_param(b, NULL, NULL, ctx, NULL, NULL))
            goto err;
        }
    else if (!(b->flags & BN_BLINDING_NO_UPDATE))
        {
        if (!BN_mod_mul(b->A,b->A,b->A,b->mod,ctx)) goto err;
        if (!BN_mod_mul(b->Ai,b->Ai,b->Ai,b->mod,ctx)) goto err;
        }

    ret=1;
err:
    if (b->counter == BN_BLINDING_COUNTER)
        b->counter = 0;
    return(ret);
    }

int BN_BLINDING_convert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
    {
    return BN_BLINDING_convert_ex(n, NULL, b, ctx);
    }

int BN_BLINDING_convert_ex(BIGNUM *n, BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
    {
    int ret = 1;

    bn_check_top(n);

    if ((b->A == NULL) || (b->Ai == NULL))
        {
        BNerr(BN_F_BN_BLINDING_CONVERT_EX,BN_R_NOT_INITIALIZED);
        return(0);
        }

    if (b->counter == -1)
        /* Fresh blinding, doesn't need updating. */
        b->counter = 0;
    else if (!BN_BLINDING_update(b,ctx))
        return(0);

    if (r != NULL)
        {
        if (!BN_copy(r, b->Ai)) ret=0;
        }

    if (!BN_mod_mul(n,n,b->A,b->mod,ctx)) ret=0;
    
    return ret;
    }

int BN_BLINDING_invert(BIGNUM *n, BN_BLINDING *b, BN_CTX *ctx)
    {
    return BN_BLINDING_invert_ex(n, NULL, b, ctx);
    }

int BN_BLINDING_invert_ex(BIGNUM *n, const BIGNUM *r, BN_BLINDING *b, BN_CTX *ctx)
    {
    int ret;

    bn_check_top(n);

    if (r != NULL)
        ret = BN_mod_mul(n, n, r, b->mod, ctx);
    else
        {
        if (b->Ai == NULL)
            {
            BNerr(BN_F_BN_BLINDING_INVERT_EX,BN_R_NOT_INITIALIZED);
            return(0);
            }
        ret = BN_mod_mul(n, n, b->Ai, b->mod, ctx);
        }

    bn_check_top(n);
    return(ret);
    }

#ifndef OPENSSL_NO_DEPRECATED
unsigned long BN_BLINDING_get_thread_id(const BN_BLINDING *b)
    {
    return b->thread_id;
    }

void BN_BLINDING_set_thread_id(BN_BLINDING *b, unsigned long n)
    {
    b->thread_id = n;
    }
#endif

CRYPTO_THREADID *BN_BLINDING_thread_id(BN_BLINDING *b)
    {
    return &b->tid;
    }

unsigned long BN_BLINDING_get_flags(const BN_BLINDING *b)
    {
    return b->flags;
    }

void BN_BLINDING_set_flags(BN_BLINDING *b, unsigned long flags)
    {
    b->flags = flags;
    }

BN_BLINDING *BN_BLINDING_create_param(BN_BLINDING *b,
    const BIGNUM *e, BIGNUM *m, BN_CTX *ctx,
    int (*bn_mod_exp)(BIGNUM *r, const BIGNUM *a, const BIGNUM *p,
              const BIGNUM *m, BN_CTX *ctx, BN_MONT_CTX *m_ctx),
    BN_MONT_CTX *m_ctx)
{
    int    retry_counter = 32;
    BN_BLINDING *ret = NULL;

    if (b == NULL)
        ret = BN_BLINDING_new(NULL, NULL, m);
    else
        ret = b;

    if (ret == NULL)
        goto err;

    if (ret->A  == NULL && (ret->A  = BN_new()) == NULL)
        goto err;
    if (ret->Ai == NULL && (ret->Ai = BN_new()) == NULL)
        goto err;

    if (e != NULL)
        {
        if (ret->e != NULL)
            BN_free(ret->e);
        ret->e = BN_dup(e);
        }
    if (ret->e == NULL)
        goto err;

    if (bn_mod_exp != NULL)
        ret->bn_mod_exp = bn_mod_exp;
    if (m_ctx != NULL)
        ret->m_ctx = m_ctx;

    do {
        if (!BN_rand_range(ret->A, ret->mod)) goto err;
        if (BN_mod_inverse(ret->Ai, ret->A, ret->mod, ctx) == NULL)
            {
            /* this should almost never happen for good RSA keys */
            unsigned long error = ERR_peek_last_error();
            if (ERR_GET_REASON(error) == BN_R_NO_INVERSE)
                {
                if (retry_counter-- == 0)
                {
                    BNerr(BN_F_BN_BLINDING_CREATE_PARAM,
                        BN_R_TOO_MANY_ITERATIONS);
                    goto err;
                }
                ERR_clear_error();
                }
            else
                goto err;
            }
        else
            break;
    } while (1);

    if (ret->bn_mod_exp != NULL && ret->m_ctx != NULL)
        {
        if (!ret->bn_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx, ret->m_ctx))
            goto err;
        }
    else
        {
        if (!BN_mod_exp(ret->A, ret->A, ret->e, ret->mod, ctx))
            goto err;
        }

    return ret;
err:
    if (b == NULL && ret != NULL)
        {
        BN_BLINDING_free(ret);
        ret = NULL;
        }

    return ret;
}