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