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316 lines
10 KiB
316 lines
10 KiB
/* crypto/bn/bn_mod.c */ |
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/* |
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* Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de> |
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* for the OpenSSL project. |
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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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/* 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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#include "cryptlib.h" |
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#include "bn_lcl.h" |
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#if 0 /* now just a #define */ |
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int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx) |
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{ |
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return (BN_div(NULL, rem, m, d, ctx)); |
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/* note that rem->neg == m->neg (unless the remainder is zero) */ |
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} |
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#endif |
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int BN_nnmod(BIGNUM *r, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx) |
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{ |
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/* |
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* like BN_mod, but returns non-negative remainder (i.e., 0 <= r < |d| |
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* always holds) |
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*/ |
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if (!(BN_mod(r, m, d, ctx))) |
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return 0; |
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if (!r->neg) |
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return 1; |
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/* now -|d| < r < 0, so we have to set r := r + |d| */ |
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return (d->neg ? BN_sub : BN_add) (r, r, d); |
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} |
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int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, |
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BN_CTX *ctx) |
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{ |
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if (!BN_add(r, a, b)) |
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return 0; |
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return BN_nnmod(r, r, m, ctx); |
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} |
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/* |
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* BN_mod_add variant that may be used if both a and b are non-negative and |
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* less than m |
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*/ |
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int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, |
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const BIGNUM *m) |
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{ |
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if (!BN_uadd(r, a, b)) |
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return 0; |
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if (BN_ucmp(r, m) >= 0) |
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return BN_usub(r, r, m); |
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return 1; |
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} |
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int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, |
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BN_CTX *ctx) |
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{ |
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if (!BN_sub(r, a, b)) |
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return 0; |
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return BN_nnmod(r, r, m, ctx); |
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} |
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/* |
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* BN_mod_sub variant that may be used if both a and b are non-negative and |
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* less than m |
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*/ |
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int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, |
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const BIGNUM *m) |
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{ |
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if (!BN_sub(r, a, b)) |
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return 0; |
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if (r->neg) |
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return BN_add(r, r, m); |
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return 1; |
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} |
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/* slow but works */ |
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int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, |
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BN_CTX *ctx) |
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{ |
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BIGNUM *t; |
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int ret = 0; |
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bn_check_top(a); |
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bn_check_top(b); |
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bn_check_top(m); |
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BN_CTX_start(ctx); |
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if ((t = BN_CTX_get(ctx)) == NULL) |
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goto err; |
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if (a == b) { |
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if (!BN_sqr(t, a, ctx)) |
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goto err; |
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} else { |
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if (!BN_mul(t, a, b, ctx)) |
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goto err; |
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} |
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if (!BN_nnmod(r, t, m, ctx)) |
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goto err; |
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bn_check_top(r); |
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ret = 1; |
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err: |
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BN_CTX_end(ctx); |
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return (ret); |
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} |
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int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx) |
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{ |
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if (!BN_sqr(r, a, ctx)) |
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return 0; |
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/* r->neg == 0, thus we don't need BN_nnmod */ |
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return BN_mod(r, r, m, ctx); |
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} |
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int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx) |
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{ |
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if (!BN_lshift1(r, a)) |
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return 0; |
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bn_check_top(r); |
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return BN_nnmod(r, r, m, ctx); |
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} |
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/* |
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* BN_mod_lshift1 variant that may be used if a is non-negative and less than |
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* m |
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*/ |
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int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *m) |
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{ |
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if (!BN_lshift1(r, a)) |
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return 0; |
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bn_check_top(r); |
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if (BN_cmp(r, m) >= 0) |
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return BN_sub(r, r, m); |
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return 1; |
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} |
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int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m, |
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BN_CTX *ctx) |
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{ |
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BIGNUM *abs_m = NULL; |
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int ret; |
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if (!BN_nnmod(r, a, m, ctx)) |
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return 0; |
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if (m->neg) { |
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abs_m = BN_dup(m); |
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if (abs_m == NULL) |
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return 0; |
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abs_m->neg = 0; |
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} |
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ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m)); |
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bn_check_top(r); |
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if (abs_m) |
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BN_free(abs_m); |
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return ret; |
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} |
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/* |
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* BN_mod_lshift variant that may be used if a is non-negative and less than |
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* m |
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*/ |
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int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m) |
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{ |
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if (r != a) { |
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if (BN_copy(r, a) == NULL) |
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return 0; |
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} |
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while (n > 0) { |
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int max_shift; |
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/* 0 < r < m */ |
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max_shift = BN_num_bits(m) - BN_num_bits(r); |
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/* max_shift >= 0 */ |
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if (max_shift < 0) { |
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BNerr(BN_F_BN_MOD_LSHIFT_QUICK, BN_R_INPUT_NOT_REDUCED); |
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return 0; |
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} |
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if (max_shift > n) |
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max_shift = n; |
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if (max_shift) { |
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if (!BN_lshift(r, r, max_shift)) |
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return 0; |
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n -= max_shift; |
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} else { |
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if (!BN_lshift1(r, r)) |
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return 0; |
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--n; |
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} |
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/* BN_num_bits(r) <= BN_num_bits(m) */ |
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if (BN_cmp(r, m) >= 0) { |
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if (!BN_sub(r, r, m)) |
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return 0; |
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} |
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} |
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bn_check_top(r); |
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return 1; |
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}
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