304 lines
11 KiB
C
304 lines
11 KiB
C
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/* crypto/bn/bn_exp2.c */
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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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* All rights reserved.
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*
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* This package is an SSL implementation written
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* by Eric Young (eay@cryptsoft.com).
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* The implementation was written so as to conform with Netscapes SSL.
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*
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* This library is free for commercial and non-commercial use as long as
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* the following conditions are aheared to. The following conditions
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* apply to all code found in this distribution, be it the RC4, RSA,
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* lhash, DES, etc., code; not just the SSL code. The SSL documentation
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* included with this distribution is covered by the same copyright terms
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* except that the holder is Tim Hudson (tjh@cryptsoft.com).
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*
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* Copyright remains Eric Young's, and as such any Copyright notices in
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* the code are not to be removed.
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* If this package is used in a product, Eric Young should be given attribution
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* as the author of the parts of the library used.
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* This can be in the form of a textual message at program startup or
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* in documentation (online or textual) provided with the package.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* "This product includes cryptographic software written by
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* Eric Young (eay@cryptsoft.com)"
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* The word 'cryptographic' can be left out if the rouines from the library
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* being used are not cryptographic related :-).
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* 4. If you include any Windows specific code (or a derivative thereof) from
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* the apps directory (application code) you must include an acknowledgement:
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* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
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*
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* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* The licence and distribution terms for any publically available version or
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* derivative of this code cannot be changed. i.e. this code cannot simply be
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* copied and put under another distribution licence
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* [including the GNU Public Licence.]
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*/
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/* ====================================================================
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* Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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*
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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*
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in
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* the documentation and/or other materials provided with the
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* distribution.
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*
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* 3. All advertising materials mentioning features or use of this
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* software must display the following acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
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*
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* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
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* endorse or promote products derived from this software without
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* prior written permission. For written permission, please contact
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* openssl-core@openssl.org.
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*
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* 5. Products derived from this software may not be called "OpenSSL"
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* nor may "OpenSSL" appear in their names without prior written
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* permission of the OpenSSL Project.
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*
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* 6. Redistributions of any form whatsoever must retain the following
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* acknowledgment:
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* "This product includes software developed by the OpenSSL Project
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* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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*
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* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
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* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
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* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
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* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
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* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
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* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
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* OF THE POSSIBILITY OF SUCH DAMAGE.
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* ====================================================================
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*
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* This product includes cryptographic software written by Eric Young
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* (eay@cryptsoft.com). This product includes software written by Tim
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* Hudson (tjh@cryptsoft.com).
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*
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*/
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#include <stdio.h>
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#include "cryptlib.h"
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#include "bn_lcl.h"
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#define TABLE_SIZE 32
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int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
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const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,
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BN_CTX *ctx, BN_MONT_CTX *in_mont)
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{
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int i, j, bits, b, bits1, bits2, ret =
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0, wpos1, wpos2, window1, window2, wvalue1, wvalue2;
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int r_is_one = 1;
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BIGNUM *d, *r;
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const BIGNUM *a_mod_m;
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/* Tables of variables obtained from 'ctx' */
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BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE];
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BN_MONT_CTX *mont = NULL;
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bn_check_top(a1);
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bn_check_top(p1);
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bn_check_top(a2);
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bn_check_top(p2);
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bn_check_top(m);
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if (!(m->d[0] & 1)) {
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BNerr(BN_F_BN_MOD_EXP2_MONT, BN_R_CALLED_WITH_EVEN_MODULUS);
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return (0);
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}
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bits1 = BN_num_bits(p1);
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bits2 = BN_num_bits(p2);
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if ((bits1 == 0) && (bits2 == 0)) {
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ret = BN_one(rr);
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return ret;
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}
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bits = (bits1 > bits2) ? bits1 : bits2;
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BN_CTX_start(ctx);
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d = BN_CTX_get(ctx);
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r = BN_CTX_get(ctx);
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val1[0] = BN_CTX_get(ctx);
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val2[0] = BN_CTX_get(ctx);
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if (!d || !r || !val1[0] || !val2[0])
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goto err;
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if (in_mont != NULL)
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mont = in_mont;
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else {
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if ((mont = BN_MONT_CTX_new()) == NULL)
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goto err;
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if (!BN_MONT_CTX_set(mont, m, ctx))
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goto err;
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}
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window1 = BN_window_bits_for_exponent_size(bits1);
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window2 = BN_window_bits_for_exponent_size(bits2);
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/*
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* Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1)
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*/
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if (a1->neg || BN_ucmp(a1, m) >= 0) {
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if (!BN_mod(val1[0], a1, m, ctx))
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goto err;
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a_mod_m = val1[0];
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} else
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a_mod_m = a1;
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if (BN_is_zero(a_mod_m)) {
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BN_zero(rr);
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ret = 1;
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goto err;
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}
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if (!BN_to_montgomery(val1[0], a_mod_m, mont, ctx))
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goto err;
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if (window1 > 1) {
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if (!BN_mod_mul_montgomery(d, val1[0], val1[0], mont, ctx))
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goto err;
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j = 1 << (window1 - 1);
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for (i = 1; i < j; i++) {
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if (((val1[i] = BN_CTX_get(ctx)) == NULL) ||
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!BN_mod_mul_montgomery(val1[i], val1[i - 1], d, mont, ctx))
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goto err;
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}
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}
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/*
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* Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1)
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*/
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if (a2->neg || BN_ucmp(a2, m) >= 0) {
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if (!BN_mod(val2[0], a2, m, ctx))
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goto err;
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a_mod_m = val2[0];
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} else
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a_mod_m = a2;
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if (BN_is_zero(a_mod_m)) {
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BN_zero(rr);
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ret = 1;
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goto err;
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}
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if (!BN_to_montgomery(val2[0], a_mod_m, mont, ctx))
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goto err;
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if (window2 > 1) {
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if (!BN_mod_mul_montgomery(d, val2[0], val2[0], mont, ctx))
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goto err;
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j = 1 << (window2 - 1);
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for (i = 1; i < j; i++) {
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if (((val2[i] = BN_CTX_get(ctx)) == NULL) ||
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!BN_mod_mul_montgomery(val2[i], val2[i - 1], d, mont, ctx))
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goto err;
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}
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}
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/* Now compute the power product, using independent windows. */
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r_is_one = 1;
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wvalue1 = 0; /* The 'value' of the first window */
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wvalue2 = 0; /* The 'value' of the second window */
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wpos1 = 0; /* If wvalue1 > 0, the bottom bit of the
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* first window */
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wpos2 = 0; /* If wvalue2 > 0, the bottom bit of the
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* second window */
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if (!BN_to_montgomery(r, BN_value_one(), mont, ctx))
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goto err;
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for (b = bits - 1; b >= 0; b--) {
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if (!r_is_one) {
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if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))
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goto err;
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}
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if (!wvalue1)
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if (BN_is_bit_set(p1, b)) {
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/*
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* consider bits b-window1+1 .. b for this window
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*/
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i = b - window1 + 1;
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while (!BN_is_bit_set(p1, i)) /* works for i<0 */
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i++;
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wpos1 = i;
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wvalue1 = 1;
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for (i = b - 1; i >= wpos1; i--) {
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wvalue1 <<= 1;
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if (BN_is_bit_set(p1, i))
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wvalue1++;
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}
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}
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if (!wvalue2)
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if (BN_is_bit_set(p2, b)) {
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/*
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* consider bits b-window2+1 .. b for this window
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*/
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i = b - window2 + 1;
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while (!BN_is_bit_set(p2, i))
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i++;
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wpos2 = i;
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wvalue2 = 1;
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for (i = b - 1; i >= wpos2; i--) {
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wvalue2 <<= 1;
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if (BN_is_bit_set(p2, i))
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wvalue2++;
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}
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}
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if (wvalue1 && b == wpos1) {
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/* wvalue1 is odd and < 2^window1 */
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if (!BN_mod_mul_montgomery(r, r, val1[wvalue1 >> 1], mont, ctx))
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goto err;
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wvalue1 = 0;
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r_is_one = 0;
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}
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if (wvalue2 && b == wpos2) {
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/* wvalue2 is odd and < 2^window2 */
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if (!BN_mod_mul_montgomery(r, r, val2[wvalue2 >> 1], mont, ctx))
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goto err;
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wvalue2 = 0;
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r_is_one = 0;
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}
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}
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if (!BN_from_montgomery(rr, r, mont, ctx))
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goto err;
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ret = 1;
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err:
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if ((in_mont == NULL) && (mont != NULL))
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BN_MONT_CTX_free(mont);
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BN_CTX_end(ctx);
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bn_check_top(rr);
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return (ret);
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}
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