Line data Source code
1 : /* crypto/bn/bn_exp2.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 : * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved.
60 : *
61 : * Redistribution and use in source and binary forms, with or without
62 : * modification, are permitted provided that the following conditions
63 : * are met:
64 : *
65 : * 1. Redistributions of source code must retain the above copyright
66 : * notice, this list of conditions and the following disclaimer.
67 : *
68 : * 2. Redistributions in binary form must reproduce the above copyright
69 : * notice, this list of conditions and the following disclaimer in
70 : * the documentation and/or other materials provided with the
71 : * distribution.
72 : *
73 : * 3. All advertising materials mentioning features or use of this
74 : * software must display the following acknowledgment:
75 : * "This product includes software developed by the OpenSSL Project
76 : * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
77 : *
78 : * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
79 : * endorse or promote products derived from this software without
80 : * prior written permission. For written permission, please contact
81 : * openssl-core@openssl.org.
82 : *
83 : * 5. Products derived from this software may not be called "OpenSSL"
84 : * nor may "OpenSSL" appear in their names without prior written
85 : * permission of the OpenSSL Project.
86 : *
87 : * 6. Redistributions of any form whatsoever must retain the following
88 : * acknowledgment:
89 : * "This product includes software developed by the OpenSSL Project
90 : * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
91 : *
92 : * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
93 : * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
94 : * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
95 : * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
96 : * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
97 : * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
98 : * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
99 : * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
100 : * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
101 : * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
102 : * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
103 : * OF THE POSSIBILITY OF SUCH DAMAGE.
104 : * ====================================================================
105 : *
106 : * This product includes cryptographic software written by Eric Young
107 : * (eay@cryptsoft.com). This product includes software written by Tim
108 : * Hudson (tjh@cryptsoft.com).
109 : *
110 : */
111 :
112 : #include <stdio.h>
113 : #include "cryptlib.h"
114 : #include "bn_lcl.h"
115 :
116 : #define TABLE_SIZE 32
117 :
118 0 : int BN_mod_exp2_mont(BIGNUM *rr, const BIGNUM *a1, const BIGNUM *p1,
119 : const BIGNUM *a2, const BIGNUM *p2, const BIGNUM *m,
120 : BN_CTX *ctx, BN_MONT_CTX *in_mont)
121 : {
122 : int i, j, bits, b, bits1, bits2, ret =
123 : 0, wpos1, wpos2, window1, window2, wvalue1, wvalue2;
124 : int r_is_one = 1;
125 : BIGNUM *d, *r;
126 : const BIGNUM *a_mod_m;
127 : /* Tables of variables obtained from 'ctx' */
128 : BIGNUM *val1[TABLE_SIZE], *val2[TABLE_SIZE];
129 : BN_MONT_CTX *mont = NULL;
130 :
131 : bn_check_top(a1);
132 : bn_check_top(p1);
133 : bn_check_top(a2);
134 : bn_check_top(p2);
135 : bn_check_top(m);
136 :
137 0 : if (!(m->d[0] & 1)) {
138 0 : BNerr(BN_F_BN_MOD_EXP2_MONT, BN_R_CALLED_WITH_EVEN_MODULUS);
139 0 : return (0);
140 : }
141 0 : bits1 = BN_num_bits(p1);
142 0 : bits2 = BN_num_bits(p2);
143 0 : if ((bits1 == 0) && (bits2 == 0)) {
144 0 : ret = BN_one(rr);
145 0 : return ret;
146 : }
147 :
148 0 : bits = (bits1 > bits2) ? bits1 : bits2;
149 :
150 0 : BN_CTX_start(ctx);
151 0 : d = BN_CTX_get(ctx);
152 0 : r = BN_CTX_get(ctx);
153 0 : val1[0] = BN_CTX_get(ctx);
154 0 : val2[0] = BN_CTX_get(ctx);
155 0 : if (!d || !r || !val1[0] || !val2[0])
156 : goto err;
157 :
158 0 : if (in_mont != NULL)
159 : mont = in_mont;
160 : else {
161 0 : if ((mont = BN_MONT_CTX_new()) == NULL)
162 : goto err;
163 0 : if (!BN_MONT_CTX_set(mont, m, ctx))
164 : goto err;
165 : }
166 :
167 0 : window1 = BN_window_bits_for_exponent_size(bits1);
168 0 : window2 = BN_window_bits_for_exponent_size(bits2);
169 :
170 : /*
171 : * Build table for a1: val1[i] := a1^(2*i + 1) mod m for i = 0 .. 2^(window1-1)
172 : */
173 0 : if (a1->neg || BN_ucmp(a1, m) >= 0) {
174 0 : if (!BN_mod(val1[0], a1, m, ctx))
175 : goto err;
176 : a_mod_m = val1[0];
177 : } else
178 : a_mod_m = a1;
179 0 : if (BN_is_zero(a_mod_m)) {
180 0 : BN_zero(rr);
181 : ret = 1;
182 0 : goto err;
183 : }
184 :
185 0 : if (!BN_to_montgomery(val1[0], a_mod_m, mont, ctx))
186 : goto err;
187 0 : if (window1 > 1) {
188 0 : if (!BN_mod_mul_montgomery(d, val1[0], val1[0], mont, ctx))
189 : goto err;
190 :
191 0 : j = 1 << (window1 - 1);
192 0 : for (i = 1; i < j; i++) {
193 0 : if (((val1[i] = BN_CTX_get(ctx)) == NULL) ||
194 0 : !BN_mod_mul_montgomery(val1[i], val1[i - 1], d, mont, ctx))
195 : goto err;
196 : }
197 : }
198 :
199 : /*
200 : * Build table for a2: val2[i] := a2^(2*i + 1) mod m for i = 0 .. 2^(window2-1)
201 : */
202 0 : if (a2->neg || BN_ucmp(a2, m) >= 0) {
203 0 : if (!BN_mod(val2[0], a2, m, ctx))
204 : goto err;
205 : a_mod_m = val2[0];
206 : } else
207 : a_mod_m = a2;
208 0 : if (BN_is_zero(a_mod_m)) {
209 0 : BN_zero(rr);
210 : ret = 1;
211 0 : goto err;
212 : }
213 0 : if (!BN_to_montgomery(val2[0], a_mod_m, mont, ctx))
214 : goto err;
215 0 : if (window2 > 1) {
216 0 : if (!BN_mod_mul_montgomery(d, val2[0], val2[0], mont, ctx))
217 : goto err;
218 :
219 0 : j = 1 << (window2 - 1);
220 0 : for (i = 1; i < j; i++) {
221 0 : if (((val2[i] = BN_CTX_get(ctx)) == NULL) ||
222 0 : !BN_mod_mul_montgomery(val2[i], val2[i - 1], d, mont, ctx))
223 : goto err;
224 : }
225 : }
226 :
227 : /* Now compute the power product, using independent windows. */
228 : r_is_one = 1;
229 : wvalue1 = 0; /* The 'value' of the first window */
230 : wvalue2 = 0; /* The 'value' of the second window */
231 : wpos1 = 0; /* If wvalue1 > 0, the bottom bit of the
232 : * first window */
233 : wpos2 = 0; /* If wvalue2 > 0, the bottom bit of the
234 : * second window */
235 :
236 0 : if (!BN_to_montgomery(r, BN_value_one(), mont, ctx))
237 : goto err;
238 0 : for (b = bits - 1; b >= 0; b--) {
239 0 : if (!r_is_one) {
240 0 : if (!BN_mod_mul_montgomery(r, r, r, mont, ctx))
241 : goto err;
242 : }
243 :
244 0 : if (!wvalue1)
245 0 : if (BN_is_bit_set(p1, b)) {
246 : /*
247 : * consider bits b-window1+1 .. b for this window
248 : */
249 0 : i = b - window1 + 1;
250 0 : while (!BN_is_bit_set(p1, i)) /* works for i<0 */
251 0 : i++;
252 : wpos1 = i;
253 : wvalue1 = 1;
254 0 : for (i = b - 1; i >= wpos1; i--) {
255 0 : wvalue1 <<= 1;
256 0 : if (BN_is_bit_set(p1, i))
257 0 : wvalue1++;
258 : }
259 : }
260 :
261 0 : if (!wvalue2)
262 0 : if (BN_is_bit_set(p2, b)) {
263 : /*
264 : * consider bits b-window2+1 .. b for this window
265 : */
266 0 : i = b - window2 + 1;
267 0 : while (!BN_is_bit_set(p2, i))
268 0 : i++;
269 : wpos2 = i;
270 : wvalue2 = 1;
271 0 : for (i = b - 1; i >= wpos2; i--) {
272 0 : wvalue2 <<= 1;
273 0 : if (BN_is_bit_set(p2, i))
274 0 : wvalue2++;
275 : }
276 : }
277 :
278 0 : if (wvalue1 && b == wpos1) {
279 : /* wvalue1 is odd and < 2^window1 */
280 0 : if (!BN_mod_mul_montgomery(r, r, val1[wvalue1 >> 1], mont, ctx))
281 : goto err;
282 : wvalue1 = 0;
283 : r_is_one = 0;
284 : }
285 :
286 0 : if (wvalue2 && b == wpos2) {
287 : /* wvalue2 is odd and < 2^window2 */
288 0 : if (!BN_mod_mul_montgomery(r, r, val2[wvalue2 >> 1], mont, ctx))
289 : goto err;
290 : wvalue2 = 0;
291 : r_is_one = 0;
292 : }
293 : }
294 0 : if (!BN_from_montgomery(rr, r, mont, ctx))
295 : goto err;
296 : ret = 1;
297 : err:
298 0 : if ((in_mont == NULL) && (mont != NULL))
299 0 : BN_MONT_CTX_free(mont);
300 0 : BN_CTX_end(ctx);
301 : bn_check_top(rr);
302 0 : return (ret);
303 : }
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