1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
2 * All rights reserved.
3 *
4 * This package is an SSL implementation written
5 * by Eric Young (eay@cryptsoft.com).
6 * The implementation was written so as to conform with Netscapes SSL.
7 *
8 * This library is free for commercial and non-commercial use as long as
9 * the following conditions are aheared to. The following conditions
10 * apply to all code found in this distribution, be it the RC4, RSA,
11 * lhash, DES, etc., code; not just the SSL code. The SSL documentation
12 * included with this distribution is covered by the same copyright terms
13 * except that the holder is Tim Hudson (tjh@cryptsoft.com).
14 *
15 * Copyright remains Eric Young's, and as such any Copyright notices in
16 * the code are not to be removed.
17 * If this package is used in a product, Eric Young should be given attribution
18 * as the author of the parts of the library used.
19 * This can be in the form of a textual message at program startup or
20 * in documentation (online or textual) provided with the package.
21 *
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
24 * are met:
25 * 1. Redistributions of source code must retain the copyright
26 * notice, this list of conditions and the following disclaimer.
27 * 2. Redistributions in binary form must reproduce the above copyright
28 * notice, this list of conditions and the following disclaimer in the
29 * documentation and/or other materials provided with the distribution.
30 * 3. All advertising materials mentioning features or use of this software
31 * must display the following acknowledgement:
32 * "This product includes cryptographic software written by
33 * Eric Young (eay@cryptsoft.com)"
34 * The word 'cryptographic' can be left out if the rouines from the library
35 * being used are not cryptographic related :-).
36 * 4. If you include any Windows specific code (or a derivative thereof) from
37 * the apps directory (application code) you must include an acknowledgement:
38 * "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
39 *
40 * THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
43 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
50 * SUCH DAMAGE.
51 *
52 * The licence and distribution terms for any publically available version or
53 * derivative of this code cannot be changed. i.e. this code cannot simply be
54 * copied and put under another distribution licence
55 * [including the GNU Public Licence.]
56 */
57 /* ====================================================================
58 * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved.
59 *
60 * Redistribution and use in source and binary forms, with or without
61 * modification, are permitted provided that the following conditions
62 * are met:
63 *
64 * 1. Redistributions of source code must retain the above copyright
65 * notice, this list of conditions and the following disclaimer.
66 *
67 * 2. Redistributions in binary form must reproduce the above copyright
68 * notice, this list of conditions and the following disclaimer in
69 * the documentation and/or other materials provided with the
70 * distribution.
71 *
72 * 3. All advertising materials mentioning features or use of this
73 * software must display the following acknowledgment:
74 * "This product includes software developed by the OpenSSL Project
75 * for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
76 *
77 * 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
78 * endorse or promote products derived from this software without
79 * prior written permission. For written permission, please contact
80 * openssl-core@openssl.org.
81 *
82 * 5. Products derived from this software may not be called "OpenSSL"
83 * nor may "OpenSSL" appear in their names without prior written
84 * permission of the OpenSSL Project.
85 *
86 * 6. Redistributions of any form whatsoever must retain the following
87 * acknowledgment:
88 * "This product includes software developed by the OpenSSL Project
89 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
90 *
91 * THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
92 * EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
93 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
94 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
95 * ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
96 * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
97 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
98 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
99 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
100 * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
101 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
102 * OF THE POSSIBILITY OF SUCH DAMAGE.
103 * ====================================================================
104 *
105 * This product includes cryptographic software written by Eric Young
106 * (eay@cryptsoft.com). This product includes software written by Tim
107 * Hudson (tjh@cryptsoft.com). */
108
109 #include <openssl/bn.h>
110
111 #include <string.h>
112
113 #include <openssl/err.h>
114 #include <openssl/mem.h>
115 #include <openssl/rand.h>
116 #include <openssl/type_check.h>
117
118 #include "internal.h"
119 #include "../../internal.h"
120 #include "../rand/internal.h"
121
122
123 static const uint8_t kDefaultAdditionalData[32] = {0};
124
BN_rand(BIGNUM * rnd,int bits,int top,int bottom)125 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom) {
126 uint8_t *buf = NULL;
127 int ret = 0, bit, bytes, mask;
128
129 if (rnd == NULL) {
130 return 0;
131 }
132
133 if (top != BN_RAND_TOP_ANY && top != BN_RAND_TOP_ONE &&
134 top != BN_RAND_TOP_TWO) {
135 OPENSSL_PUT_ERROR(BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
136 return 0;
137 }
138
139 if (bottom != BN_RAND_BOTTOM_ANY && bottom != BN_RAND_BOTTOM_ODD) {
140 OPENSSL_PUT_ERROR(BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
141 return 0;
142 }
143
144 if (bits == 0) {
145 BN_zero(rnd);
146 return 1;
147 }
148
149 bytes = (bits + 7) / 8;
150 bit = (bits - 1) % 8;
151 mask = 0xff << (bit + 1);
152
153 buf = OPENSSL_malloc(bytes);
154 if (buf == NULL) {
155 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
156 goto err;
157 }
158
159 // Make a random number and set the top and bottom bits.
160 RAND_bytes(buf, bytes);
161
162 if (top != BN_RAND_TOP_ANY) {
163 if (top == BN_RAND_TOP_TWO && bits > 1) {
164 if (bit == 0) {
165 buf[0] = 1;
166 buf[1] |= 0x80;
167 } else {
168 buf[0] |= (3 << (bit - 1));
169 }
170 } else {
171 buf[0] |= (1 << bit);
172 }
173 }
174
175 buf[0] &= ~mask;
176
177 // Set the bottom bit if requested,
178 if (bottom == BN_RAND_BOTTOM_ODD) {
179 buf[bytes - 1] |= 1;
180 }
181
182 if (!BN_bin2bn(buf, bytes, rnd)) {
183 goto err;
184 }
185
186 ret = 1;
187
188 err:
189 OPENSSL_free(buf);
190 return ret;
191 }
192
BN_pseudo_rand(BIGNUM * rnd,int bits,int top,int bottom)193 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) {
194 return BN_rand(rnd, bits, top, bottom);
195 }
196
197 // bn_less_than_word returns one if the number represented by |len| words at |a|
198 // is less than |b| and zero otherwise. It performs this computation in time
199 // independent of the value of |a|. |b| is assumed public.
bn_less_than_word(const BN_ULONG * a,size_t len,BN_ULONG b)200 static int bn_less_than_word(const BN_ULONG *a, size_t len, BN_ULONG b) {
201 if (b == 0) {
202 return 0;
203 }
204 if (len == 0) {
205 return 1;
206 }
207
208 // |a| < |b| iff a[1..len-1] are all zero and a[0] < b.
209 OPENSSL_COMPILE_ASSERT(sizeof(BN_ULONG) <= sizeof(crypto_word_t),
210 crypto_word_t_too_small);
211 crypto_word_t mask = 0;
212 for (size_t i = 1; i < len; i++) {
213 mask |= a[i];
214 }
215 // |mask| is now zero iff a[1..len-1] are all zero.
216 mask = constant_time_is_zero_w(mask);
217 mask &= constant_time_lt_w(a[0], b);
218 return constant_time_select_int(mask, 1, 0);
219 }
220
bn_in_range_words(const BN_ULONG * a,BN_ULONG min_inclusive,const BN_ULONG * max_exclusive,size_t len)221 int bn_in_range_words(const BN_ULONG *a, BN_ULONG min_inclusive,
222 const BN_ULONG *max_exclusive, size_t len) {
223 return bn_less_than_words(a, max_exclusive, len) &&
224 !bn_less_than_word(a, len, min_inclusive);
225 }
226
bn_rand_range_words(BN_ULONG * out,BN_ULONG min_inclusive,const BN_ULONG * max_exclusive,size_t len,const uint8_t additional_data[32])227 int bn_rand_range_words(BN_ULONG *out, BN_ULONG min_inclusive,
228 const BN_ULONG *max_exclusive, size_t len,
229 const uint8_t additional_data[32]) {
230 // This function implements the equivalent of steps 4 through 7 of FIPS 186-4
231 // appendices B.4.2 and B.5.2. When called in those contexts, |max_exclusive|
232 // is n and |min_inclusive| is one.
233
234 // Compute the bit length of |max_exclusive| (step 1), in terms of a number of
235 // |words| worth of entropy to fill and a mask of bits to clear in the top
236 // word.
237 size_t words = len;
238 while (words > 0 && max_exclusive[words - 1] == 0) {
239 words--;
240 }
241 if (words == 0 ||
242 (words == 1 && max_exclusive[0] <= min_inclusive)) {
243 OPENSSL_PUT_ERROR(BN, BN_R_INVALID_RANGE);
244 return 0;
245 }
246 BN_ULONG mask = max_exclusive[words - 1];
247 // This sets all bits in |mask| below the most significant bit.
248 mask |= mask >> 1;
249 mask |= mask >> 2;
250 mask |= mask >> 4;
251 mask |= mask >> 8;
252 mask |= mask >> 16;
253 #if defined(OPENSSL_64_BIT)
254 mask |= mask >> 32;
255 #endif
256
257 // Fill any unused words with zero.
258 OPENSSL_memset(out + words, 0, (len - words) * sizeof(BN_ULONG));
259
260 unsigned count = 100;
261 do {
262 if (!--count) {
263 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_ITERATIONS);
264 return 0;
265 }
266
267 // Steps 4 and 5. Use |words| and |mask| together to obtain a string of N
268 // bits, where N is the bit length of |max_exclusive|.
269 RAND_bytes_with_additional_data((uint8_t *)out, words * sizeof(BN_ULONG),
270 additional_data);
271 out[words - 1] &= mask;
272
273 // If out >= max_exclusive or out < min_inclusive, retry. This implements
274 // the equivalent of steps 6 and 7 without leaking the value of |out|.
275 } while (!bn_in_range_words(out, min_inclusive, max_exclusive, words));
276 return 1;
277 }
278
BN_rand_range_ex(BIGNUM * r,BN_ULONG min_inclusive,const BIGNUM * max_exclusive)279 int BN_rand_range_ex(BIGNUM *r, BN_ULONG min_inclusive,
280 const BIGNUM *max_exclusive) {
281 if (!bn_wexpand(r, max_exclusive->top) ||
282 !bn_rand_range_words(r->d, min_inclusive, max_exclusive->d,
283 max_exclusive->top, kDefaultAdditionalData)) {
284 return 0;
285 }
286
287 r->neg = 0;
288 r->top = max_exclusive->top;
289 bn_correct_top(r);
290 return 1;
291 }
292
BN_rand_range(BIGNUM * r,const BIGNUM * range)293 int BN_rand_range(BIGNUM *r, const BIGNUM *range) {
294 return BN_rand_range_ex(r, 0, range);
295 }
296
BN_pseudo_rand_range(BIGNUM * r,const BIGNUM * range)297 int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) {
298 return BN_rand_range(r, range);
299 }
300