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535b9b57 | 1 | /* crypto/bn/bn_mod.c */ |
40720ce3 MC |
2 | /* |
3 | * Includes code written by Lenka Fibikova <fibikova@exp-math.uni-essen.de> | |
4 | * for the OpenSSL project. | |
5 | */ | |
535b9b57 BM |
6 | /* ==================================================================== |
7 | * Copyright (c) 1998-2000 The OpenSSL Project. All rights reserved. | |
8 | * | |
9 | * Redistribution and use in source and binary forms, with or without | |
10 | * modification, are permitted provided that the following conditions | |
11 | * are met: | |
12 | * | |
13 | * 1. Redistributions of source code must retain the above copyright | |
40720ce3 | 14 | * notice, this list of conditions and the following disclaimer. |
535b9b57 BM |
15 | * |
16 | * 2. Redistributions in binary form must reproduce the above copyright | |
17 | * notice, this list of conditions and the following disclaimer in | |
18 | * the documentation and/or other materials provided with the | |
19 | * distribution. | |
20 | * | |
21 | * 3. All advertising materials mentioning features or use of this | |
22 | * software must display the following acknowledgment: | |
23 | * "This product includes software developed by the OpenSSL Project | |
24 | * for use in the OpenSSL Toolkit. (http://www.openssl.org/)" | |
25 | * | |
26 | * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to | |
27 | * endorse or promote products derived from this software without | |
28 | * prior written permission. For written permission, please contact | |
29 | * openssl-core@openssl.org. | |
30 | * | |
31 | * 5. Products derived from this software may not be called "OpenSSL" | |
32 | * nor may "OpenSSL" appear in their names without prior written | |
33 | * permission of the OpenSSL Project. | |
34 | * | |
35 | * 6. Redistributions of any form whatsoever must retain the following | |
36 | * acknowledgment: | |
37 | * "This product includes software developed by the OpenSSL Project | |
38 | * for use in the OpenSSL Toolkit (http://www.openssl.org/)" | |
39 | * | |
40 | * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY | |
41 | * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
42 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR | |
43 | * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR | |
44 | * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, | |
45 | * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT | |
46 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; | |
47 | * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
48 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, | |
49 | * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) | |
50 | * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED | |
51 | * OF THE POSSIBILITY OF SUCH DAMAGE. | |
52 | * ==================================================================== | |
53 | * | |
54 | * This product includes cryptographic software written by Eric Young | |
55 | * (eay@cryptsoft.com). This product includes software written by Tim | |
56 | * Hudson (tjh@cryptsoft.com). | |
57 | * | |
58 | */ | |
59 | /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com) | |
60 | * All rights reserved. | |
61 | * | |
62 | * This package is an SSL implementation written | |
63 | * by Eric Young (eay@cryptsoft.com). | |
64 | * The implementation was written so as to conform with Netscapes SSL. | |
40720ce3 | 65 | * |
535b9b57 BM |
66 | * This library is free for commercial and non-commercial use as long as |
67 | * the following conditions are aheared to. The following conditions | |
68 | * apply to all code found in this distribution, be it the RC4, RSA, | |
69 | * lhash, DES, etc., code; not just the SSL code. The SSL documentation | |
70 | * included with this distribution is covered by the same copyright terms | |
71 | * except that the holder is Tim Hudson (tjh@cryptsoft.com). | |
40720ce3 | 72 | * |
535b9b57 BM |
73 | * Copyright remains Eric Young's, and as such any Copyright notices in |
74 | * the code are not to be removed. | |
75 | * If this package is used in a product, Eric Young should be given attribution | |
76 | * as the author of the parts of the library used. | |
77 | * This can be in the form of a textual message at program startup or | |
78 | * in documentation (online or textual) provided with the package. | |
40720ce3 | 79 | * |
535b9b57 BM |
80 | * Redistribution and use in source and binary forms, with or without |
81 | * modification, are permitted provided that the following conditions | |
82 | * are met: | |
83 | * 1. Redistributions of source code must retain the copyright | |
84 | * notice, this list of conditions and the following disclaimer. | |
85 | * 2. Redistributions in binary form must reproduce the above copyright | |
86 | * notice, this list of conditions and the following disclaimer in the | |
87 | * documentation and/or other materials provided with the distribution. | |
88 | * 3. All advertising materials mentioning features or use of this software | |
89 | * must display the following acknowledgement: | |
90 | * "This product includes cryptographic software written by | |
91 | * Eric Young (eay@cryptsoft.com)" | |
92 | * The word 'cryptographic' can be left out if the rouines from the library | |
93 | * being used are not cryptographic related :-). | |
40720ce3 | 94 | * 4. If you include any Windows specific code (or a derivative thereof) from |
535b9b57 BM |
95 | * the apps directory (application code) you must include an acknowledgement: |
96 | * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)" | |
40720ce3 | 97 | * |
535b9b57 BM |
98 | * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND |
99 | * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE | |
100 | * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE | |
101 | * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE | |
102 | * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL | |
103 | * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS | |
104 | * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) | |
105 | * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT | |
106 | * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY | |
107 | * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF | |
108 | * SUCH DAMAGE. | |
40720ce3 | 109 | * |
535b9b57 BM |
110 | * The licence and distribution terms for any publically available version or |
111 | * derivative of this code cannot be changed. i.e. this code cannot simply be | |
112 | * copied and put under another distribution licence | |
113 | * [including the GNU Public Licence.] | |
114 | */ | |
115 | ||
116 | #include "cryptlib.h" | |
117 | #include "bn_lcl.h" | |
118 | ||
40720ce3 | 119 | #if 0 /* now just a #define */ |
535b9b57 | 120 | int BN_mod(BIGNUM *rem, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx) |
40720ce3 MC |
121 | { |
122 | return (BN_div(NULL, rem, m, d, ctx)); | |
123 | /* note that rem->neg == m->neg (unless the remainder is zero) */ | |
124 | } | |
535b9b57 BM |
125 | #endif |
126 | ||
5acaa495 | 127 | int BN_nnmod(BIGNUM *r, const BIGNUM *m, const BIGNUM *d, BN_CTX *ctx) |
40720ce3 MC |
128 | { |
129 | /* | |
130 | * like BN_mod, but returns non-negative remainder (i.e., 0 <= r < |d| | |
131 | * always holds) | |
132 | */ | |
133 | ||
134 | if (!(BN_mod(r, m, d, ctx))) | |
135 | return 0; | |
136 | if (!r->neg) | |
137 | return 1; | |
138 | /* now -|d| < r < 0, so we have to set r := r + |d| */ | |
139 | return (d->neg ? BN_sub : BN_add) (r, r, d); | |
535b9b57 BM |
140 | } |
141 | ||
40720ce3 MC |
142 | int BN_mod_add(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, |
143 | BN_CTX *ctx) | |
144 | { | |
145 | if (!BN_add(r, a, b)) | |
146 | return 0; | |
147 | return BN_nnmod(r, r, m, ctx); | |
148 | } | |
535b9b57 | 149 | |
40720ce3 MC |
150 | /* |
151 | * BN_mod_add variant that may be used if both a and b are non-negative and | |
152 | * less than m | |
153 | */ | |
154 | int BN_mod_add_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, | |
155 | const BIGNUM *m) | |
156 | { | |
157 | if (!BN_uadd(r, a, b)) | |
158 | return 0; | |
159 | if (BN_ucmp(r, m) >= 0) | |
160 | return BN_usub(r, r, m); | |
161 | return 1; | |
162 | } | |
5acaa495 | 163 | |
40720ce3 MC |
164 | int BN_mod_sub(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, |
165 | BN_CTX *ctx) | |
166 | { | |
167 | if (!BN_sub(r, a, b)) | |
168 | return 0; | |
169 | return BN_nnmod(r, r, m, ctx); | |
170 | } | |
535b9b57 | 171 | |
40720ce3 MC |
172 | /* |
173 | * BN_mod_sub variant that may be used if both a and b are non-negative and | |
174 | * less than m | |
175 | */ | |
176 | int BN_mod_sub_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, | |
177 | const BIGNUM *m) | |
178 | { | |
179 | if (!BN_sub(r, a, b)) | |
180 | return 0; | |
181 | if (r->neg) | |
182 | return BN_add(r, r, m); | |
183 | return 1; | |
184 | } | |
535b9b57 BM |
185 | |
186 | /* slow but works */ | |
5acaa495 | 187 | int BN_mod_mul(BIGNUM *r, const BIGNUM *a, const BIGNUM *b, const BIGNUM *m, |
40720ce3 MC |
188 | BN_CTX *ctx) |
189 | { | |
190 | BIGNUM *t; | |
191 | int ret = 0; | |
192 | ||
193 | bn_check_top(a); | |
194 | bn_check_top(b); | |
195 | bn_check_top(m); | |
196 | ||
197 | BN_CTX_start(ctx); | |
198 | if ((t = BN_CTX_get(ctx)) == NULL) | |
199 | goto err; | |
200 | if (a == b) { | |
201 | if (!BN_sqr(t, a, ctx)) | |
202 | goto err; | |
203 | } else { | |
204 | if (!BN_mul(t, a, b, ctx)) | |
205 | goto err; | |
206 | } | |
207 | if (!BN_nnmod(r, t, m, ctx)) | |
208 | goto err; | |
209 | bn_check_top(r); | |
210 | ret = 1; | |
211 | err: | |
212 | BN_CTX_end(ctx); | |
213 | return (ret); | |
214 | } | |
535b9b57 | 215 | |
5acaa495 | 216 | int BN_mod_sqr(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx) |
40720ce3 MC |
217 | { |
218 | if (!BN_sqr(r, a, ctx)) | |
219 | return 0; | |
220 | /* r->neg == 0, thus we don't need BN_nnmod */ | |
221 | return BN_mod(r, r, m, ctx); | |
222 | } | |
5acaa495 BM |
223 | |
224 | int BN_mod_lshift1(BIGNUM *r, const BIGNUM *a, const BIGNUM *m, BN_CTX *ctx) | |
40720ce3 MC |
225 | { |
226 | if (!BN_lshift1(r, a)) | |
227 | return 0; | |
228 | bn_check_top(r); | |
229 | return BN_nnmod(r, r, m, ctx); | |
230 | } | |
5acaa495 | 231 | |
40720ce3 MC |
232 | /* |
233 | * BN_mod_lshift1 variant that may be used if a is non-negative and less than | |
234 | * m | |
235 | */ | |
5acaa495 | 236 | int BN_mod_lshift1_quick(BIGNUM *r, const BIGNUM *a, const BIGNUM *m) |
40720ce3 MC |
237 | { |
238 | if (!BN_lshift1(r, a)) | |
239 | return 0; | |
240 | bn_check_top(r); | |
241 | if (BN_cmp(r, m) >= 0) | |
242 | return BN_sub(r, r, m); | |
243 | return 1; | |
244 | } | |
5acaa495 | 245 | |
40720ce3 MC |
246 | int BN_mod_lshift(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m, |
247 | BN_CTX *ctx) | |
248 | { | |
249 | BIGNUM *abs_m = NULL; | |
250 | int ret; | |
5acaa495 | 251 | |
40720ce3 MC |
252 | if (!BN_nnmod(r, a, m, ctx)) |
253 | return 0; | |
5acaa495 | 254 | |
40720ce3 MC |
255 | if (m->neg) { |
256 | abs_m = BN_dup(m); | |
257 | if (abs_m == NULL) | |
258 | return 0; | |
259 | abs_m->neg = 0; | |
260 | } | |
5acaa495 | 261 | |
40720ce3 MC |
262 | ret = BN_mod_lshift_quick(r, r, n, (abs_m ? abs_m : m)); |
263 | bn_check_top(r); | |
5acaa495 | 264 | |
40720ce3 MC |
265 | if (abs_m) |
266 | BN_free(abs_m); | |
267 | return ret; | |
268 | } | |
5acaa495 | 269 | |
40720ce3 MC |
270 | /* |
271 | * BN_mod_lshift variant that may be used if a is non-negative and less than | |
272 | * m | |
273 | */ | |
5acaa495 | 274 | int BN_mod_lshift_quick(BIGNUM *r, const BIGNUM *a, int n, const BIGNUM *m) |
40720ce3 MC |
275 | { |
276 | if (r != a) { | |
277 | if (BN_copy(r, a) == NULL) | |
278 | return 0; | |
279 | } | |
280 | ||
281 | while (n > 0) { | |
282 | int max_shift; | |
283 | ||
284 | /* 0 < r < m */ | |
285 | max_shift = BN_num_bits(m) - BN_num_bits(r); | |
286 | /* max_shift >= 0 */ | |
287 | ||
288 | if (max_shift < 0) { | |
289 | BNerr(BN_F_BN_MOD_LSHIFT_QUICK, BN_R_INPUT_NOT_REDUCED); | |
290 | return 0; | |
291 | } | |
292 | ||
293 | if (max_shift > n) | |
294 | max_shift = n; | |
295 | ||
296 | if (max_shift) { | |
297 | if (!BN_lshift(r, r, max_shift)) | |
298 | return 0; | |
299 | n -= max_shift; | |
300 | } else { | |
301 | if (!BN_lshift1(r, r)) | |
302 | return 0; | |
303 | --n; | |
304 | } | |
305 | ||
306 | /* BN_num_bits(r) <= BN_num_bits(m) */ | |
307 | ||
308 | if (BN_cmp(r, m) >= 0) { | |
309 | if (!BN_sub(r, r, m)) | |
310 | return 0; | |
311 | } | |
312 | } | |
313 | bn_check_top(r); | |
314 | ||
315 | return 1; | |
316 | } |