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131 lines
4.0 KiB
C
131 lines
4.0 KiB
C
/* crypto/bn/bn_word.c */
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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 <stdio.h>
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#include "bn_lcl.h"
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int BN_add_word(BIGNUM *a, BN_ULONG w)
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{
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BN_ULONG l;
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int i;
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if (a->neg)
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{
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a->neg=0;
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i=BN_sub_word(a,w);
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if (!BN_is_zero(a))
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a->neg=!(a->neg);
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return(i);
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}
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w&=BN_MASK2;
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if (bn_wexpand(a,a->top+1) == NULL) return(0);
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i=0;
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for (;;)
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{
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l=(a->d[i]+(BN_ULONG)w)&BN_MASK2;
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a->d[i]=l;
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if (w > l)
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w=1;
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else
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break;
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i++;
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}
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if (i >= a->top)
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a->top++;
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return(1);
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}
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int BN_sub_word(BIGNUM *a, BN_ULONG w)
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{
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int i;
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if (BN_is_zero(a) || a->neg)
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{
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a->neg=0;
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i=BN_add_word(a,w);
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a->neg=1;
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return(i);
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}
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w&=BN_MASK2;
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if ((a->top == 1) && (a->d[0] < w))
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{
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a->d[0]=w-a->d[0];
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a->neg=1;
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return(1);
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}
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i=0;
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for (;;)
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{
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if (a->d[i] >= w)
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{
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a->d[i]-=w;
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break;
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}
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else
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{
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a->d[i]=(a->d[i]-w)&BN_MASK2;
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i++;
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w=1;
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}
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}
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if ((a->d[i] == 0) && (i == (a->top-1)))
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a->top--;
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return(1);
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}
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