crypto/bn/bn_m.c

   1 /* crypto/bn/bn_m.c */
   2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
   3  * All rights reserved.
   4  *
   5  * This package is an SSL implementation written
   6  * by Eric Young (eay@cryptsoft.com).
   7  * The implementation was written so as to conform with Netscapes SSL.
   8  *
   9  * This library is free for commercial and non-commercial use as long as
  10  * the following conditions are aheared to.  The following conditions
  11  * apply to all code found in this distribution, be it the RC4, RSA,
  12  * lhash, DES, etc., code; not just the SSL code.  The SSL documentation
  13  * included with this distribution is covered by the same copyright terms
  14  * except that the holder is Tim Hudson (tjh@cryptsoft.com).
  15  *
  16  * Copyright remains Eric Young's, and as such any Copyright notices in
  17  * the code are not to be removed.
  18  * If this package is used in a product, Eric Young should be given attribution
  19  * as the author of the parts of the library used.
  20  * This can be in the form of a textual message at program startup or
  21  * in documentation (online or textual) provided with the package.
  22  *
  23  * Redistribution and use in source and binary forms, with or without
  24  * modification, are permitted provided that the following conditions
  25  * are met:
  26  * 1. Redistributions of source code must retain the copyright
  27  *    notice, this list of conditions and the following disclaimer.
  28  * 2. Redistributions in binary form must reproduce the above copyright
  29  *    notice, this list of conditions and the following disclaimer in the
  30  *    documentation and/or other materials provided with the distribution.
  31  * 3. All advertising materials mentioning features or use of this software
  32  *    must display the following acknowledgement:
  33  *    "This product includes cryptographic software written by
  34  *     Eric Young (eay@cryptsoft.com)"
  35  *    The word 'cryptographic' can be left out if the rouines from the library
  36  *    being used are not cryptographic related :-).
  37  * 4. If you include any Windows specific code (or a derivative thereof) from
  38  *    the apps directory (application code) you must include an acknowledgement:
  39  *    "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
  40  *
  41  * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
  42  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  43  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  44  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
  45  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  46  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  47  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  48  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  49  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  50  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  51  * SUCH DAMAGE.
  52  *
  53  * The licence and distribution terms for any publically available version or
  54  * derivative of this code cannot be changed.  i.e. this code cannot simply be
  55  * copied and put under another distribution licence
  56  * [including the GNU Public Licence.]
  57  */
  58
  59 #include <stdio.h>
  60 #include "cryptlib.h"
  61 #include "bn_lcl.h"
  62 #include "stack.h"
  63
  64 int limit=16;
  65
  66 typedef struct bn_pool_st
  67         {
  68         int used;
  69         int tos;
  70         STACK *sk;
  71         } BN_POOL;
  72
  73 BIGNUM *BN_POOL_push(bp)
  74 BN_POOL *bp;
  75         {
  76         BIGNUM *ret;
  77
  78         if (bp->used >= bp->tos)
  79                 {
  80                 ret=BN_new();
  81                 sk_push(bp->sk,(char *)ret);
  82                 bp->tos++;
  83                 bp->used++;
  84                 }
  85         else
  86                 {
  87                 ret=(BIGNUM *)sk_value(bp->sk,bp->used);
  88                 bp->used++;
  89                 }
  90         return(ret);
  91         }
  92
  93 void BN_POOL_pop(bp,num)
  94 BN_POOL *bp;
  95 int num;
  96         {
  97         bp->used-=num;
  98         }
  99
 100 int BN_m(r,a,b)
 101 BIGNUM *r,*a,*b;
 102         {
 103         static BN_POOL bp;
 104         static init=1;
 105
 106         if (init)
 107                 {
 108                 bp.used=0;
 109                 bp.tos=0;
 110                 bp.sk=sk_new_null();
 111                 init=0;
 112                 }
 113         return(BN_mm(r,a,b,&bp));
 114         }
 115
 116 /* r must be different to a and b */
 117 int BN_mm(m, A, B, bp)
 118 BIGNUM *m,*A,*B;
 119 BN_POOL *bp;
 120         {
 121         int i,num;
 122         int an,bn;
 123         BIGNUM *a,*b,*c,*d,*ac,*bd;
 124
 125         an=A->top;
 126         bn=B->top;
 127         if ((an <= limit) || (bn <= limit))
 128                 {
 129                 return(BN_mul(m,A,B));
 130                 }
 131
 132         a=BN_POOL_push(bp);
 133         b=BN_POOL_push(bp);
 134         c=BN_POOL_push(bp);
 135         d=BN_POOL_push(bp);
 136         ac=BN_POOL_push(bp);
 137         bd=BN_POOL_push(bp);
 138
 139         num=(an <= bn)?an:bn;
 140         num=1<<(BN_num_bits_word(num-1)-1);
 141
 142         /* Are going to now chop things into 'num' word chunks. */
 143         num*=BN_BITS2;
 144
 145         BN_copy(a,A);
 146         BN_mask_bits(a,num);
 147         BN_rshift(b,A,num);
 148
 149         BN_copy(c,B);
 150         BN_mask_bits(c,num);
 151         BN_rshift(d,B,num);
 152
 153         BN_sub(ac ,b,a);
 154         BN_sub(bd,c,d);
 155         BN_mm(m,ac,bd,bp);
 156         BN_mm(ac,a,c,bp);
 157         BN_mm(bd,b,d,bp);
 158
 159         BN_add(m,m,ac);
 160         BN_add(m,m,bd);
 161         BN_lshift(m,m,num);
 162         BN_lshift(bd,bd,num*2);
 163
 164         BN_add(m,m,ac);
 165         BN_add(m,m,bd);
 166         BN_POOL_pop(bp,6);
 167         return(1);
 168         }
 169