302 lines
9.5 KiB
C
302 lines
9.5 KiB
C
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/* crypto/bn/bn_mod.c */
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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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* 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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/* like BN_mod, but returns non-negative remainder
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* (i.e., 0 <= r < |d| always holds) */
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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, BN_CTX *ctx)
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{
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if (!BN_add(r, a, b)) return 0;
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return BN_nnmod(r, r, m, ctx);
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}
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/* BN_mod_add variant that may be used if both a and b are non-negative
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* and less than m */
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int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m)
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{
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if (!BN_uadd(r, a, b)) 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, BN_CTX *ctx)
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{
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if (!BN_sub(r, a, b)) return 0;
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return BN_nnmod(r, r, m, ctx);
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}
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/* BN_mod_sub variant that may be used if both a and b are non-negative
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* and less than m */
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int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m)
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{
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if (!BN_sub(r, a, b)) 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) goto err;
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if (a == b)
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{ if (!BN_sqr(t,a,ctx)) goto err; }
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else
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{ if (!BN_mul(t,a,b,ctx)) goto err; }
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if (!BN_nnmod(r,t,m,ctx)) 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)) 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)) 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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/* BN_mod_lshift1 variant that may be used if a is non-negative
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* and less than m */
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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)) 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, 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)) return 0;
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if (m->neg)
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{
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abs_m = BN_dup(m);
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if (abs_m == NULL) 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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/* BN_mod_lshift variant that may be used if a is non-negative
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* and less than m */
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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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{
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if (BN_copy(r, a) == NULL) return 0;
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}
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while (n > 0)
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{
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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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{
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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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{
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if (!BN_lshift(r, r, max_shift)) return 0;
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n -= max_shift;
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}
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else
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{
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if (!BN_lshift1(r, r)) 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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{
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if (!BN_sub(r, r, m)) 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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