1 /* $OpenBSD: bn_rand.c,v 1.30 2024/03/16 20:42:33 tb Exp $ */
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) 1998-2001 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 <limits.h>
113 #include <stdio.h>
114 #include <stdlib.h>
115 #include <string.h>
116 #include <time.h>
117
118 #include <openssl/err.h>
119
120 #include "bn_local.h"
121
122 static int
bnrand(int pseudorand,BIGNUM * rnd,int bits,int top,int bottom)123 bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
124 {
125 unsigned char *buf = NULL;
126 int ret = 0, bit, bytes, mask;
127
128 if (rnd == NULL) {
129 BNerror(ERR_R_PASSED_NULL_PARAMETER);
130 return (0);
131 }
132
133 if (bits < 0 || (bits == 1 && top > 0)) {
134 BNerror(BN_R_BITS_TOO_SMALL);
135 return (0);
136 }
137 if (bits > INT_MAX - 7) {
138 BNerror(BN_R_BIGNUM_TOO_LONG);
139 return (0);
140 }
141
142 if (bits == 0) {
143 BN_zero(rnd);
144 return (1);
145 }
146
147 bytes = (bits + 7) / 8;
148 bit = (bits - 1) % 8;
149 mask = 0xff << (bit + 1);
150
151 buf = malloc(bytes);
152 if (buf == NULL) {
153 BNerror(ERR_R_MALLOC_FAILURE);
154 goto err;
155 }
156
157 /* make a random number and set the top and bottom bits */
158 arc4random_buf(buf, bytes);
159
160 #if 1
161 if (pseudorand == 2) {
162 /* generate patterns that are more likely to trigger BN
163 library bugs */
164 int i;
165 unsigned char c;
166
167 for (i = 0; i < bytes; i++) {
168 arc4random_buf(&c, 1);
169 if (c >= 128 && i > 0)
170 buf[i] = buf[i - 1];
171 else if (c < 42)
172 buf[i] = 0;
173 else if (c < 84)
174 buf[i] = 255;
175 }
176 }
177 #endif
178
179 if (top > 0) {
180 if (bit == 0) {
181 buf[0] = 1;
182 buf[1] |= 0x80;
183 } else {
184 buf[0] |= (3 << (bit - 1));
185 }
186 }
187 if (top == 0)
188 buf[0] |= (1 << bit);
189 buf[0] &= ~mask;
190 if (bottom) /* set bottom bit if requested */
191 buf[bytes - 1] |= 1;
192 if (BN_bin2bn(buf, bytes, rnd) == NULL)
193 goto err;
194 ret = 1;
195
196 err:
197 freezero(buf, bytes);
198 return (ret);
199 }
200
201 int
BN_rand(BIGNUM * rnd,int bits,int top,int bottom)202 BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
203 {
204 return bnrand(0, rnd, bits, top, bottom);
205 }
206 LCRYPTO_ALIAS(BN_rand);
207
208 int
BN_pseudo_rand(BIGNUM * rnd,int bits,int top,int bottom)209 BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
210 {
211 return bnrand(1, rnd, bits, top, bottom);
212 }
213 LCRYPTO_ALIAS(BN_pseudo_rand);
214
215 #if 1
216 int
BN_bntest_rand(BIGNUM * rnd,int bits,int top,int bottom)217 BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom)
218 {
219 return bnrand(2, rnd, bits, top, bottom);
220 }
221 #endif
222
223
224 /* random number r: 0 <= r < range */
225 static int
bn_rand_range(int pseudo,BIGNUM * r,const BIGNUM * range)226 bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range)
227 {
228 int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand;
229 int n;
230 int count = 100;
231
232 if (range->neg || BN_is_zero(range)) {
233 BNerror(BN_R_INVALID_RANGE);
234 return 0;
235 }
236
237 n = BN_num_bits(range); /* n > 0 */
238
239 /* BN_is_bit_set(range, n - 1) always holds */
240
241 if (n == 1)
242 BN_zero(r);
243 else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3)) {
244 /* range = 100..._2,
245 * so 3*range (= 11..._2) is exactly one bit longer than range */
246 do {
247 if (!bn_rand(r, n + 1, -1, 0))
248 return 0;
249 /* If r < 3*range, use r := r MOD range
250 * (which is either r, r - range, or r - 2*range).
251 * Otherwise, iterate once more.
252 * Since 3*range = 11..._2, each iteration succeeds with
253 * probability >= .75. */
254 if (BN_cmp(r, range) >= 0) {
255 if (!BN_sub(r, r, range))
256 return 0;
257 if (BN_cmp(r, range) >= 0)
258 if (!BN_sub(r, r, range))
259 return 0;
260 }
261
262 if (!--count) {
263 BNerror(BN_R_TOO_MANY_ITERATIONS);
264 return 0;
265 }
266
267 } while (BN_cmp(r, range) >= 0);
268 } else {
269 do {
270 /* range = 11..._2 or range = 101..._2 */
271 if (!bn_rand(r, n, -1, 0))
272 return 0;
273
274 if (!--count) {
275 BNerror(BN_R_TOO_MANY_ITERATIONS);
276 return 0;
277 }
278 } while (BN_cmp(r, range) >= 0);
279 }
280
281 return 1;
282 }
283
284 int
BN_rand_range(BIGNUM * r,const BIGNUM * range)285 BN_rand_range(BIGNUM *r, const BIGNUM *range)
286 {
287 return bn_rand_range(0, r, range);
288 }
289 LCRYPTO_ALIAS(BN_rand_range);
290
291 int
bn_rand_in_range(BIGNUM * rnd,const BIGNUM * lower_inc,const BIGNUM * upper_exc)292 bn_rand_in_range(BIGNUM *rnd, const BIGNUM *lower_inc, const BIGNUM *upper_exc)
293 {
294 BIGNUM *len;
295 int ret = 0;
296
297 if ((len = BN_new()) == NULL)
298 goto err;
299 if (!BN_sub(len, upper_exc, lower_inc))
300 goto err;
301 if (!BN_rand_range(rnd, len))
302 goto err;
303 if (!BN_add(rnd, rnd, lower_inc))
304 goto err;
305
306 ret = 1;
307
308 err:
309 BN_free(len);
310
311 return ret;
312 }
313
314 int
bn_rand_interval(BIGNUM * rnd,BN_ULONG lower_word,const BIGNUM * upper_exc)315 bn_rand_interval(BIGNUM *rnd, BN_ULONG lower_word, const BIGNUM *upper_exc)
316 {
317 BIGNUM *lower_inc = NULL;
318 int ret = 0;
319
320 if ((lower_inc = BN_new()) == NULL)
321 goto err;
322 if (!BN_set_word(lower_inc, lower_word))
323 goto err;
324 if (!bn_rand_in_range(rnd, lower_inc, upper_exc))
325 goto err;
326
327 ret = 1;
328
329 err:
330 BN_free(lower_inc);
331
332 return ret;
333 }
334
335 int
BN_pseudo_rand_range(BIGNUM * r,const BIGNUM * range)336 BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range)
337 {
338 return bn_rand_range(1, r, range);
339 }
340 LCRYPTO_ALIAS(BN_pseudo_rand_range);
341