1 /* crypto/bn/bn_mul.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
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)"
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
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.]
63 static int bn_mm_low(BIGNUM *m,BIGNUM *A,BIGNUM *B, int num,
64 BIGNUM *sk,BN_CTX *ctx);
65 int BN_mul_low(BIGNUM *r, BIGNUM *a, BIGNUM *b,int words);
67 /* r must be different to a and b */
68 int BN_mul_low(r, a, b, num)
84 printf("BN_mul_low(%d,%d,%d)\n",a->top,b->top,num);
89 if ((al == 0) || (bl == 0))
95 if ((bn_limit_bits_low > 0) && (num > bn_limit_num_low))
97 n=BN_num_bits_word(num*2)-bn_limit_bits_low;
99 sk=(BIGNUM *)Malloc(sizeof(BIGNUM)*n);
100 memset(sk,0,sizeof(BIGNUM)*n);
101 memset(&ctx,0,sizeof(ctx));
103 ret=bn_mm_low(r,a,b,num,&(sk[0]),&ctx);
106 BN_clear_free(&sk[i]);
107 BN_clear_free(&sk[i+1]);
114 if (bn_wexpand(r,max) == NULL) return(0);
115 r->neg=a->neg^b->neg;
119 r->top=(max > num)?num:max;
121 rp[al]=bn_mul_words(rp,ap,al,*(bp++));
131 rp[al]=bn_mul_add_words(rp,ap,al,*(bp++));
135 while ((r->top > 0) && (r->d[r->top-1] == 0))
144 /* r must be different to a and b */
145 int bn_mm_low(m, A, B, num, sk,ctx)
160 printf("bn_mm_low(%d,%d,%d)\n",A->top,B->top,num);
165 BN_init(&ah); BN_init(&al); BN_init(&bh); BN_init(&bl);
167 bn_set_low( &al,A,n);
168 bn_set_high(&ah,A,n);
169 bn_set_low( &bl,B,n);
170 bn_set_high(&bh,B,n);
172 if (num <= (bn_limit_num_low+bn_limit_num_low))
175 BN_mul_low(&t1,&al,&bh,n);
176 BN_mul_low(&t2,&ah,&bl,n);
180 bn_mm(m ,&al,&bl,&(sk[2]),ctx);
181 bn_mm_low(&t1,&al,&bh,n,&(sk[2]),ctx);
182 bn_mm_low(&t2,&ah,&bl,n,&(sk[2]),ctx);
187 /* We will now do an evil hack instead of
188 * BN_lshift(&t1,&t1,n*BN_BITS2);
190 * BN_mask_bits(m,num*BN_BITS2);
192 bn_set_high(&ah,m,n); ah.max=num+2;
196 m->neg=A->neg^B->neg;