| /* 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; |
| } |
| } |
| if (!BN_from_montgomery(rr, r, mont, ctx)) |
| goto err; |
| ret = 1; |
| err: |
| if ((in_mont == NULL) && (mont != NULL)) |
| BN_MONT_CTX_free(mont); |
| BN_CTX_end(ctx); |
| bn_check_top(rr); |
| return (ret); |
| } |
