/* crypto/bn/bn_exp2.c */
/* 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.]
*/
/* ====================================================================
* 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"
#include "bn_lcl.h"
#define TABLE_SIZE 32
int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,
BN_CTX *ctx, BN_MONT_CTX *in_mont)
{
int i,j,bits,b,bits1,bits2,ret=0,wpos1,wpos2,window1,window2,wvalue1,wvalue2;
int r_is_one=1;
BIGNUM *d,*r;
const BIGNUM *a_mod_m;
/* Tables of variables obtained from 'ctx' */
BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE];
BN_MONT_CTX *mont=NULL;
bn_check_top(a1);
bn_check_top(p1);
bn_check_top(a2);
bn_check_top(p2);
bn_check_top(m);
if (!(m->d[0] & 1))
{
BNerr(BN_F_BN_MOD_EXP2_MONT,BN_R_CALLED_WITH_EVEN_MODULUS);
return(0);
}
bits1=BN_num_bits(p1);
bits2=BN_num_bits(p2);
if ((bits1 == 0) && (bits2 == 0))
{
ret = BN_one(rr);
return ret;
}
bits=(bits1 > bits2)?bits1:bits2;
BN_CTX_start(ctx);
d = BN_CTX_get(ctx);
r = BN_CTX_get(ctx);
val1[0] = BN_CTX_get(ctx);
val2[0] = BN_CTX_get(ctx);
if(!d || !r || !val1[0] || !val2[0]) goto err;
if (in_mont != NULL)
mont=in_mont;
else
{
if ((mont=BN_MONT_CTX_new()) == NULL) goto err;
if (!BN_MONT_CTX_set(mont,m,ctx)) goto err;
}
window1 = BN_window_bits_for_exponent_size(bits1);
window2 = BN_window_bits_for_exponent_size(bits2);
/*
* Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1)
*/
if (a1->neg || BN_ucmp(a1,m) >= 0)
{
if (!BN_mod(val1[0],a1,m,ctx))
goto err;
a_mod_m = val1[0];
}
else
a_mod_m = a1;
if (BN_is_zero(a_mod_m))
{
BN_zero(rr);
ret = 1;
goto err;
}
if (!BN_to_montgomery(val1[0],a_mod_m,mont,ctx)) goto err;
if (window1 > 1)
{
if (!BN_mod_mul_montgomery(d,val1[0],val1[0],mont,ctx)) goto err;
j=1<<(window1-1);
for (i=1; i<j; i++)
{
if(((val1[i] = BN_CTX_get(ctx)) == NULL) ||
!BN_mod_mul_montgomery(val1[i],val1[i-1],
d,mont,ctx))
goto err;
}
}
/*
* Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1)
*/
if (a2->neg || BN_ucmp(a2,m) >= 0)
{
if (!BN_mod(val2[0],a2,m,ctx))
goto err;
a_mod_m = val2[0];
}
else
a_mod_m = a2;
if (BN_is_zero(a_mod_m))
{
BN_zero(rr);
ret = 1;
goto err;
}
if (!BN_to_montgomery(val2[0],a_mod_m,mont,ctx)) goto err;
if (window2 > 1)
{
if (!BN_mod_mul_montgomery(d,val2[0],val2[0],mont,ctx)) goto err;
j=1<<(window2-1);
for (i=1; i<j; i++)
{
if(((val2[i] = BN_CTX_get(ctx)) == NULL) ||
!BN_mod_mul_montgomery(val2[i],val2[i-1],
d,mont,ctx))
goto err;
}
}
/* Now compute the power product, using independent windows. */
r_is_one=1;
wvalue1=0; /* The 'value' of the first window */
wvalue2=0; /* The 'value' of the second window */
wpos1=0; /* If wvalue1 > 0, the bottom bit of the first window */
wpos2=0; /* If wvalue2 > 0, the bottom bit of the second window */
if (!BN_to_montgomery(r,BN_value_one(),mont,ctx)) goto err;
for (b=bits-1; b>=0; b--)
{
if (!r_is_one)
{
if (!BN_mod_mul_montgomery(r,r,r,mont,ctx))
goto err;
}
if (!wvalue1)
if (BN_is_bit_set(p1, b))
{
/* consider bits b-window1+1 .. b for this window */
i = b-window1+1;
while (!BN_is_bit_set(p1, i)) /* works for i<0 */
i++;
wpos1 = i;
wvalue1 = 1;
for (i = b-1; i >= wpos1; i--)
{
wvalue1 <<= 1;
if (BN_is_bit_set(p1, i))
wvalue1++;
}
}
if (!wvalue2)
if (BN_is_bit_set(p2, b))
{
/* consider bits b-window2+1 .. b for this window */
i = b-window2+1;
while (!BN_is_bit_set(p2, i))
i++;
wpos2 = i;
wvalue2 = 1;
for (i = b-1; i >= wpos2; i--)
{
wvalue2 <<= 1;
if (BN_is_bit_set(p2, i))
wvalue2++;
}
}
if (wvalue1 && b == wpos1)
{
/* wvalue1 is odd and < 2^window1 */
if (!BN_mod_mul_montgomery(r,r,val1[wvalue1>>1],mont,ctx))
goto err;
wvalue1 = 0;
r_is_one = 0;
}
if (wvalue2 && b == wpos2)
{
/* wvalue2 is odd and < 2^window2 */
if (!BN_mod_mul_montgomery(r,r,val2[wvalue2>>1],mont,ctx))
goto err;
wvalue2 = 0;
r_is_one = 0;
}
}
BN_from_montgomery(rr,r,mont,ctx);
ret=1;
err:
if ((in_mont == NULL) && (mont != NULL)) BN_MONT_CTX_free(mont);
BN_CTX_end(ctx);
bn_check_top(rr);
return(ret);
}
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