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
 *    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).
 *
 */
/* 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 <openssl/opensslconf.h>
#include "internal/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 */
    CRYPTO_THREAD_ID 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);
    CRYPTO_RWLOCK *lock;
};

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

    bn_check_top(mod);

    if ((ret = OPENSSL_zalloc(sizeof(*ret))) == NULL) {
        BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE);
        return NULL;
    }

    ret->lock = CRYPTO_THREAD_lock_new();
    if (ret->lock == NULL) {
        BNerr(BN_F_BN_BLINDING_NEW, ERR_R_MALLOC_FAILURE);
        OPENSSL_free(ret);
        return NULL;
    }

    BN_BLINDING_set_current_thread(ret);

    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;

    return ret;

 err:
    BN_BLINDING_free(ret);
    return NULL;
}

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

    BN_free(r->A);
    BN_free(r->Ai);
    BN_free(r->e);
    BN_free(r->mod);
    CRYPTO_THREAD_lock_free(r->lock);
    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);
}

int BN_BLINDING_is_current_thread(BN_BLINDING *b)
{
    return CRYPTO_THREAD_compare_id(CRYPTO_THREAD_get_current_id(), b->tid);
}

void BN_BLINDING_set_current_thread(BN_BLINDING *b)
{
    b->tid = CRYPTO_THREAD_get_current_id();
}

int BN_BLINDING_lock(BN_BLINDING *b)
{
    return CRYPTO_THREAD_write_lock(b->lock);
}

int BN_BLINDING_unlock(BN_BLINDING *b)
{
    return CRYPTO_THREAD_unlock(b->lock);
}

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) {
        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 {
        int rv;
        if (!BN_rand_range(ret->A, ret->mod))
            goto err;
        if (!int_bn_mod_inverse(ret->Ai, ret->A, ret->mod, ctx, &rv)) {
            /*
             * this should almost never happen for good RSA keys
             */
            if (rv) {
                if (retry_counter-- == 0) {
                    BNerr(BN_F_BN_BLINDING_CREATE_PARAM,
                          BN_R_TOO_MANY_ITERATIONS);
                    goto err;
                }
            } 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) {
        BN_BLINDING_free(ret);
        ret = NULL;
    }

    return ret;
}