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1 | /* crypto/bn/bn_mul.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 | ||
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); | |
66 | ||
67 | /* r must be different to a and b */ | |
6b691a5c | 68 | int BN_mul_low(BIGNUM *r, BIGNUM *a, BIGNUM *b, int num) |
dfeab068 RE |
69 | { |
70 | BN_ULONG *ap,*bp,*rp; | |
71 | BIGNUM *sk; | |
72 | int j,i,n,ret; | |
73 | int max,al,bl; | |
74 | BN_CTX ctx; | |
75 | ||
76 | bn_check_top(a); | |
77 | bn_check_top(b); | |
78 | ||
79 | #ifdef BN_MUL_DEBUG | |
80 | printf("BN_mul_low(%d,%d,%d)\n",a->top,b->top,num); | |
81 | #endif | |
82 | ||
83 | al=a->top; | |
84 | bl=b->top; | |
85 | if ((al == 0) || (bl == 0)) | |
86 | { | |
87 | r->top=0; | |
88 | return(1); | |
89 | } | |
90 | ||
91 | if ((bn_limit_bits_low > 0) && (num > bn_limit_num_low)) | |
92 | { | |
93 | n=BN_num_bits_word(num*2)-bn_limit_bits_low; | |
94 | n*=2; | |
95 | sk=(BIGNUM *)Malloc(sizeof(BIGNUM)*n); | |
96 | memset(sk,0,sizeof(BIGNUM)*n); | |
97 | memset(&ctx,0,sizeof(ctx)); | |
98 | ||
99 | ret=bn_mm_low(r,a,b,num,&(sk[0]),&ctx); | |
100 | for (i=0; i<n; i+=2) | |
101 | { | |
102 | BN_clear_free(&sk[i]); | |
103 | BN_clear_free(&sk[i+1]); | |
104 | } | |
105 | Free(sk); | |
106 | return(ret); | |
107 | } | |
108 | ||
109 | max=(al+bl); | |
110 | if (bn_wexpand(r,max) == NULL) return(0); | |
111 | r->neg=a->neg^b->neg; | |
112 | ap=a->d; | |
113 | bp=b->d; | |
114 | rp=r->d; | |
115 | r->top=(max > num)?num:max; | |
116 | ||
117 | rp[al]=bn_mul_words(rp,ap,al,*(bp++)); | |
118 | rp++; | |
119 | j=bl; | |
120 | for (i=1; i<j; i++) | |
121 | { | |
122 | if (al >= num--) | |
123 | { | |
124 | al--; | |
125 | if (al <= 0) break; | |
126 | } | |
127 | rp[al]=bn_mul_add_words(rp,ap,al,*(bp++)); | |
128 | rp++; | |
129 | } | |
130 | ||
131 | while ((r->top > 0) && (r->d[r->top-1] == 0)) | |
132 | r->top--; | |
133 | return(1); | |
134 | } | |
135 | ||
136 | ||
137 | #define t1 (sk[0]) | |
138 | #define t2 (sk[1]) | |
139 | ||
140 | /* r must be different to a and b */ | |
6b691a5c UM |
141 | int bn_mm_low(BIGNUM *m, BIGNUM *A, BIGNUM *B, int num, BIGNUM *sk, |
142 | BN_CTX *ctx) | |
dfeab068 RE |
143 | { |
144 | int n; /* ,sqr=0; */ | |
145 | int an,bn; | |
146 | BIGNUM ah,al,bh,bl; | |
147 | ||
148 | bn_wexpand(m,num+3); | |
149 | an=A->top; | |
150 | bn=B->top; | |
151 | ||
152 | #ifdef BN_MUL_DEBUG | |
153 | printf("bn_mm_low(%d,%d,%d)\n",A->top,B->top,num); | |
154 | #endif | |
155 | ||
156 | n=(num+1)/2; | |
157 | ||
158 | BN_init(&ah); BN_init(&al); BN_init(&bh); BN_init(&bl); | |
159 | ||
160 | bn_set_low( &al,A,n); | |
161 | bn_set_high(&ah,A,n); | |
162 | bn_set_low( &bl,B,n); | |
163 | bn_set_high(&bh,B,n); | |
164 | ||
165 | if (num <= (bn_limit_num_low+bn_limit_num_low)) | |
166 | { | |
167 | BN_mul(m,&al,&bl); | |
168 | BN_mul_low(&t1,&al,&bh,n); | |
169 | BN_mul_low(&t2,&ah,&bl,n); | |
170 | } | |
171 | else | |
172 | { | |
173 | bn_mm(m ,&al,&bl,&(sk[2]),ctx); | |
174 | bn_mm_low(&t1,&al,&bh,n,&(sk[2]),ctx); | |
175 | bn_mm_low(&t2,&ah,&bl,n,&(sk[2]),ctx); | |
176 | } | |
177 | ||
178 | BN_add(&t1,&t1,&t2); | |
179 | ||
180 | /* We will now do an evil hack instead of | |
181 | * BN_lshift(&t1,&t1,n*BN_BITS2); | |
182 | * BN_add(m,m,&t1); | |
183 | * BN_mask_bits(m,num*BN_BITS2); | |
184 | */ | |
185 | bn_set_high(&ah,m,n); ah.max=num+2; | |
186 | BN_add(&ah,&ah,&t1); | |
187 | m->top=num; | |
188 | ||
189 | m->neg=A->neg^B->neg; | |
190 | return(1); | |
191 | } | |
192 | ||
193 | #undef t1 (sk[0]) | |
194 | #undef t2 (sk[1]) |