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 <assert.h>
112 #include <limits.h>
113 #include <string.h>
114
115 #include <openssl/err.h>
116 #include <openssl/rand.h>
117
118 #include "../../internal.h"
119 #include "../rand/internal.h"
120 #include "../service_indicator/internal.h"
121 #include "internal.h"
122
123
BN_rand(BIGNUM * rnd,int bits,int top,int bottom)124 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom) {
125 if (rnd == NULL) {
126 return 0;
127 }
128
129 if (top != BN_RAND_TOP_ANY && top != BN_RAND_TOP_ONE &&
130 top != BN_RAND_TOP_TWO) {
131 OPENSSL_PUT_ERROR(BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
132 return 0;
133 }
134
135 if (bottom != BN_RAND_BOTTOM_ANY && bottom != BN_RAND_BOTTOM_ODD) {
136 OPENSSL_PUT_ERROR(BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
137 return 0;
138 }
139
140 if (bits == 0) {
141 BN_zero(rnd);
142 return 1;
143 }
144
145 if (bits > INT_MAX - (BN_BITS2 - 1)) {
146 OPENSSL_PUT_ERROR(BN, BN_R_BIGNUM_TOO_LONG);
147 return 0;
148 }
149
150 int words = (bits + BN_BITS2 - 1) / BN_BITS2;
151 int bit = (bits - 1) % BN_BITS2;
152 const BN_ULONG kOne = 1;
153 const BN_ULONG kThree = 3;
154 BN_ULONG mask = bit < BN_BITS2 - 1 ? (kOne << (bit + 1)) - 1 : BN_MASK2;
155 if (!bn_wexpand(rnd, words)) {
156 return 0;
157 }
158
159 FIPS_service_indicator_lock_state();
160 RAND_bytes((uint8_t *)rnd->d, words * sizeof(BN_ULONG));
161 FIPS_service_indicator_unlock_state();
162
163 rnd->d[words - 1] &= mask;
164 if (top != BN_RAND_TOP_ANY) {
165 if (top == BN_RAND_TOP_TWO && bits > 1) {
166 if (bit == 0) {
167 rnd->d[words - 1] |= 1;
168 rnd->d[words - 2] |= kOne << (BN_BITS2 - 1);
169 } else {
170 rnd->d[words - 1] |= kThree << (bit - 1);
171 }
172 } else {
173 rnd->d[words - 1] |= kOne << bit;
174 }
175 }
176 if (bottom == BN_RAND_BOTTOM_ODD) {
177 rnd->d[0] |= 1;
178 }
179
180 rnd->neg = 0;
181 rnd->width = words;
182 return 1;
183 }
184
BN_pseudo_rand(BIGNUM * rnd,int bits,int top,int bottom)185 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) {
186 return BN_rand(rnd, bits, top, bottom);
187 }
188
189 // bn_less_than_word_mask returns a mask of all ones if the number represented
190 // by |len| words at |a| is less than |b| and zero otherwise. It performs this
191 // computation in time independent of the value of |a|. |b| is assumed public.
bn_less_than_word_mask(const BN_ULONG * a,size_t len,BN_ULONG b)192 static crypto_word_t bn_less_than_word_mask(const BN_ULONG *a, size_t len,
193 BN_ULONG b) {
194 if (b == 0) {
195 return CONSTTIME_FALSE_W;
196 }
197 if (len == 0) {
198 return CONSTTIME_TRUE_W;
199 }
200
201 // |a| < |b| iff a[1..len-1] are all zero and a[0] < b.
202 static_assert(sizeof(BN_ULONG) <= sizeof(crypto_word_t),
203 "crypto_word_t is too small");
204 crypto_word_t mask = 0;
205 for (size_t i = 1; i < len; i++) {
206 mask |= a[i];
207 }
208 // |mask| is now zero iff a[1..len-1] are all zero.
209 mask = constant_time_is_zero_w(mask);
210 mask &= constant_time_lt_w(a[0], b);
211 return mask;
212 }
213
bn_in_range_words(const BN_ULONG * a,BN_ULONG min_inclusive,const BN_ULONG * max_exclusive,size_t len)214 int bn_in_range_words(const BN_ULONG *a, BN_ULONG min_inclusive,
215 const BN_ULONG *max_exclusive, size_t len) {
216 crypto_word_t mask = ~bn_less_than_word_mask(a, len, min_inclusive);
217 return mask & bn_less_than_words(a, max_exclusive, len);
218 }
219
bn_range_to_mask(size_t * out_words,BN_ULONG * out_mask,size_t min_inclusive,const BN_ULONG * max_exclusive,size_t len)220 static int bn_range_to_mask(size_t *out_words, BN_ULONG *out_mask,
221 size_t min_inclusive, const BN_ULONG *max_exclusive,
222 size_t len) {
223 // The magnitude of |max_exclusive| is assumed public.
224 size_t words = len;
225 while (words > 0 && max_exclusive[words - 1] == 0) {
226 words--;
227 }
228 if (words == 0 ||
229 (words == 1 && max_exclusive[0] <= min_inclusive)) {
230 OPENSSL_PUT_ERROR(BN, BN_R_INVALID_RANGE);
231 return 0;
232 }
233 BN_ULONG mask = max_exclusive[words - 1];
234 // This sets all bits in |mask| below the most significant bit.
235 mask |= mask >> 1;
236 mask |= mask >> 2;
237 mask |= mask >> 4;
238 mask |= mask >> 8;
239 mask |= mask >> 16;
240 #if defined(OPENSSL_64_BIT)
241 mask |= mask >> 32;
242 #endif
243
244 *out_words = words;
245 *out_mask = mask;
246 return 1;
247 }
248
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])249 int bn_rand_range_words(BN_ULONG *out, BN_ULONG min_inclusive,
250 const BN_ULONG *max_exclusive, size_t len,
251 const uint8_t additional_data[32]) {
252 // This function implements the equivalent of steps 4 through 7 of FIPS 186-4
253 // appendices B.4.2 and B.5.2. When called in those contexts, |max_exclusive|
254 // is n and |min_inclusive| is one.
255
256 // Compute the bit length of |max_exclusive| (step 1), in terms of a number of
257 // |words| worth of entropy to fill and a mask of bits to clear in the top
258 // word.
259 size_t words;
260 BN_ULONG mask;
261 if (!bn_range_to_mask(&words, &mask, min_inclusive, max_exclusive, len)) {
262 return 0;
263 }
264
265 // Fill any unused words with zero.
266 OPENSSL_memset(out + words, 0, (len - words) * sizeof(BN_ULONG));
267
268 unsigned count = 100;
269 do {
270 if (!--count) {
271 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_ITERATIONS);
272 return 0;
273 }
274
275 // Steps 4 and 5. Use |words| and |mask| together to obtain a string of N
276 // bits, where N is the bit length of |max_exclusive|.
277 FIPS_service_indicator_lock_state();
278 RAND_bytes_with_additional_data((uint8_t *)out, words * sizeof(BN_ULONG),
279 additional_data);
280 FIPS_service_indicator_unlock_state();
281 out[words - 1] &= mask;
282
283 // If out >= max_exclusive or out < min_inclusive, retry. This implements
284 // the equivalent of steps 6 and 7 without leaking the value of |out|.
285 } while (!bn_in_range_words(out, min_inclusive, max_exclusive, words));
286 return 1;
287 }
288
BN_rand_range_ex(BIGNUM * r,BN_ULONG min_inclusive,const BIGNUM * max_exclusive)289 int BN_rand_range_ex(BIGNUM *r, BN_ULONG min_inclusive,
290 const BIGNUM *max_exclusive) {
291 static const uint8_t kDefaultAdditionalData[32] = {0};
292 if (!bn_wexpand(r, max_exclusive->width) ||
293 !bn_rand_range_words(r->d, min_inclusive, max_exclusive->d,
294 max_exclusive->width, kDefaultAdditionalData)) {
295 return 0;
296 }
297
298 r->neg = 0;
299 r->width = max_exclusive->width;
300 return 1;
301 }
302
bn_rand_secret_range(BIGNUM * r,int * out_is_uniform,BN_ULONG min_inclusive,const BIGNUM * max_exclusive)303 int bn_rand_secret_range(BIGNUM *r, int *out_is_uniform, BN_ULONG min_inclusive,
304 const BIGNUM *max_exclusive) {
305 size_t words;
306 BN_ULONG mask;
307 if (!bn_range_to_mask(&words, &mask, min_inclusive, max_exclusive->d,
308 max_exclusive->width) ||
309 !bn_wexpand(r, words)) {
310 return 0;
311 }
312
313 assert(words > 0);
314 assert(mask != 0);
315 // The range must be large enough for bit tricks to fix invalid values.
316 if (words == 1 && min_inclusive > mask >> 1) {
317 OPENSSL_PUT_ERROR(BN, BN_R_INVALID_RANGE);
318 return 0;
319 }
320
321 // Select a uniform random number with num_bits(max_exclusive) bits.
322 FIPS_service_indicator_lock_state();
323 RAND_bytes((uint8_t *)r->d, words * sizeof(BN_ULONG));
324 FIPS_service_indicator_unlock_state();
325 r->d[words - 1] &= mask;
326
327 // Check, in constant-time, if the value is in range.
328 *out_is_uniform =
329 bn_in_range_words(r->d, min_inclusive, max_exclusive->d, words);
330 crypto_word_t in_range = *out_is_uniform;
331 in_range = 0 - in_range;
332
333 // If the value is not in range, force it to be in range.
334 r->d[0] |= constant_time_select_w(in_range, 0, min_inclusive);
335 r->d[words - 1] &= constant_time_select_w(in_range, BN_MASK2, mask >> 1);
336 assert(bn_in_range_words(r->d, min_inclusive, max_exclusive->d, words));
337
338 r->neg = 0;
339 r->width = (int)words;
340 return 1;
341 }
342
BN_rand_range(BIGNUM * r,const BIGNUM * range)343 int BN_rand_range(BIGNUM *r, const BIGNUM *range) {
344 return BN_rand_range_ex(r, 0, range);
345 }
346
BN_pseudo_rand_range(BIGNUM * r,const BIGNUM * range)347 int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) {
348 return BN_rand_range(r, range);
349 }
350