crypto/bn/bn_blind.c

/* $OpenBSD: bn_blind.c,v 1.17 2017/01/29 17:49:22 beck Exp $ */
/* ====================================================================
 * 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 <stdio.h>

#include <openssl/opensslconf.h>

#include <openssl/err.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 = calloc(1, sizeof(BN_BLINDING))) == NULL) {
		BNerror(ERR_R_MALLOC_FAILURE);
		return (NULL);
	}
	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;

	BN_clear_free(r->A);
	BN_clear_free(r->Ai);
	BN_clear_free(r->e);
	BN_clear_free(r->mod);
	free(r);
}

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

	if ((b->A == NULL) || (b->Ai == NULL)) {
		BNerror(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)) {
		BNerror(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) {
			BNerror(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) {
		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_ct(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) {
					BNerror(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_ct(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;
}