Use the equivalent of a sliding window (without precomputation (f8989a21) · Commits · CYBER - Cyber Security / TS 103 523 MSP / TLMSP / TLMSP OpenSSL

CHANGES

+2 −3

Original line number	Diff line number	Diff line
		@@ -4,9 +4,8 @@

		Changes between 0.9.5a and 0.9.6 [xx XXX 2000]

		*) New function BN_mod_exp_mont_word for small bases (roughly 20%
		faster than BN_mod_exp_mont even though it does not use
		windowing).
		*) New function BN_mod_exp_mont_word for small bases (roughly 15-20%
		faster than BN_mod_exp_mont).
		[Bodo Moeller]

		*) CygWin32 support.

crypto/bn/bn_exp.c

+93 −14

Original line number	Diff line number	Diff line
		@@ -55,6 +55,60 @@
		* copied and put under another distribution licence
		* [including the GNU Public Licence.]
		*/
		/* ====================================================================
		* Copyright (c) 1998-2000 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"
		@@ -611,11 +665,17 @@ err:

		int BN_mod_exp_mont_word(BIGNUM rr, BN_ULONG a, const BIGNUM p,
		const BIGNUM m, BN_CTX ctx, BN_MONT_CTX *in_mont)
		/* if we had BN_mod_exp_mont_2, we could even use windowing in it */
		{
		BN_MONT_CTX *mont = NULL;
		int b, bits, ret=0;
		BN_ULONG w, next_w;
		BIGNUM d, r, *t;
		BN_MONT_CTX *mont = NULL;
		BIGNUM *swap_tmp;
		#define BN_MOD_MUL_WORD(r, w, m) \
		(BN_mul_word(r, (w)) && \
		(BN_ucmp(r, (m)) >= 0 ? \
		(BN_mod(t, r, m, ctx) && (swap_tmp = r, r = t, t = swap_tmp, 1)) : \
		1))

		bn_check_top(p);
		bn_check_top(m);
		@@ -656,26 +716,45 @@ int BN_mod_exp_mont_word(BIGNUM rr, BN_ULONG a, const BIGNUM p,
		}

		if (!BN_to_montgomery(r, BN_value_one(), mont, ctx)) goto err;
		for (b = bits-1; b >= 0; b--)

		/* bits-1 >= 0 */

		/* The result is accumulated in the product rw. /
		w = a; /* bit 'bits-1' of 'p' is always set */
		for (b = bits-2; b >= 0; b--)
		{
		if (BN_is_bit_set(p, b))
		/* First, square rw. /
		next_w = w*w;
		if ((next_w/w) != w) /* overflow */
		{
		if (!BN_mul_word(r, a))
		if (!BN_MOD_MUL_WORD(r, w, m))
		goto err;
		next_w = 1;
		}
		w = next_w;
		if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))
		goto err;
		if (BN_ucmp(r, m) >= 0)

		/* Second, multiply rw by 'a' if exponent bit is set. /
		if (BN_is_bit_set(p, b))
		{
		if (!BN_mod(t, r, m, ctx))
		next_w = w*a;
		if ((next_w/a) != w) /* overflow */
		{
		if (!BN_MOD_MUL_WORD(r, w, m))
		goto err;
		{ BIGNUM *swap_tmp = r; r = t; t = swap_tmp; }
		next_w = a;
		}
		w = next_w;
		}

		if (b > 0)
		}
		/* Finally, set r:=rw. /
		if (w != 1)
		{
		if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))
		if (!BN_MOD_MUL_WORD(r, w, m))
		goto err;
		}
		}

		BN_from_montgomery(rr, r, mont, ctx);
		ret = 1;
		err: