139 lines
4.4 KiB
C
139 lines
4.4 KiB
C
/* crypto/bn/bn_m.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 "cryptlib.h"*/
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#include "bn_lcl.h"
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#define limit_bits 5 /* 2^5, or 32 words */
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#define limit_num (1<<limit_bits)
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int BN_m(BIGNUM *r, BIGNUM *a, BIGNUM *b)
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{
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BIGNUM *sk;
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int i,n;
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n=(BN_num_bits_word(a->top|b->top)-limit_bits);
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n*=2;
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sk=(BIGNUM *)malloc(sizeof(BIGNUM)*n);
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for (i=0; i<n; i++)
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BN_init(&(sk[i]));
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return(BN_mm(r,a,b,&(sk[0])));
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}
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#define ahal (sk[0])
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#define blbh (sk[1])
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/* r must be different to a and b */
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int BN_mm(BIGNUM *m, BIGNUM *A, BIGNUM *B, BIGNUM *sk)
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{
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int i,num,anum,bnum;
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int an,bn;
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BIGNUM ah,al,bh,bl;
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an=A->top;
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bn=B->top;
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if ((an <= limit_num) || (bn <= limit_num))
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{
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return(BN_mul(m,A,B));
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}
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anum=(an>bn)?an:bn;
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num=(anum)/2;
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/* Are going to now chop things into 'num' word chunks. */
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bnum=num*BN_BITS2;
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BN_init(&ahal);
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BN_init(&blbh);
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BN_init(&ah);
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BN_init(&al);
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BN_init(&bh);
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BN_init(&bl);
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al.top=num;
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al.d=A->d;
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ah.top=A->top-num;
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ah.d= &(A->d[num]);
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bl.top=num;
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bl.d=B->d;
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bh.top=B->top-num;
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bh.d= &(B->d[num]);
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BN_sub(&ahal,&ah,&al);
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BN_sub(&blbh,&bl,&bh);
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BN_mm(m,&ahal,&blbh,&(sk[2]));
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BN_mm(&ahal,&al,&bl,&(sk[2]));
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BN_mm(&blbh,&ah,&bh,&(sk[2]));
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BN_add(m,m,&ahal);
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BN_add(m,m,&blbh);
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BN_lshift(m,m,bnum);
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BN_add(m,m,&ahal);
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BN_lshift(&blbh,&blbh,bnum*2);
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BN_add(m,m,&blbh);
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m->neg=A->neg^B->neg;
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return(1);
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}
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