1 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
22 * Redistribution and use in source and binary forms, with or without
23 * modification, are permitted provided that the following conditions
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)"
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
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.]
57 /* ====================================================================
58 * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved.
60 * Redistribution and use in source and binary forms, with or without
61 * modification, are permitted provided that the following conditions
64 * 1. Redistributions of source code must retain the above copyright
65 * notice, this list of conditions and the following disclaimer.
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
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/)"
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.
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.
86 * 6. Redistributions of any form whatsoever must retain the following
88 * "This product includes software developed by the OpenSSL Project
89 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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 * ====================================================================
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). */
109 #include <openssl/bn.h>
113 #include <openssl/err.h>
114 #include <openssl/mem.h>
115 #include <openssl/rand.h>
116 #include <openssl/type_check.h>
118 #include "internal.h"
119 #include "../../internal.h"
120 #include "../rand/internal.h"
123 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom) {
125 int ret = 0, bit, bytes, mask;
131 if (top != BN_RAND_TOP_ANY && top != BN_RAND_TOP_ONE &&
132 top != BN_RAND_TOP_TWO) {
133 OPENSSL_PUT_ERROR(BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
137 if (bottom != BN_RAND_BOTTOM_ANY && bottom != BN_RAND_BOTTOM_ODD) {
138 OPENSSL_PUT_ERROR(BN, ERR_R_SHOULD_NOT_HAVE_BEEN_CALLED);
147 bytes = (bits + 7) / 8;
148 bit = (bits - 1) % 8;
149 mask = 0xff << (bit + 1);
151 buf = OPENSSL_malloc(bytes);
153 OPENSSL_PUT_ERROR(BN, ERR_R_MALLOC_FAILURE);
157 // Make a random number and set the top and bottom bits.
158 RAND_bytes(buf, bytes);
160 if (top != BN_RAND_TOP_ANY) {
161 if (top == BN_RAND_TOP_TWO && bits > 1) {
166 buf[0] |= (3 << (bit - 1));
169 buf[0] |= (1 << bit);
175 // Set the bottom bit if requested,
176 if (bottom == BN_RAND_BOTTOM_ODD) {
180 if (!BN_bin2bn(buf, bytes, rnd)) {
191 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom) {
192 return BN_rand(rnd, bits, top, bottom);
195 // bn_less_than_word_mask returns a mask of all ones if the number represented
196 // by |len| words at |a| is less than |b| and zero otherwise. It performs this
197 // computation in time independent of the value of |a|. |b| is assumed public.
198 static crypto_word_t bn_less_than_word_mask(const BN_ULONG *a, size_t len,
201 return CONSTTIME_FALSE_W;
204 return CONSTTIME_TRUE_W;
207 // |a| < |b| iff a[1..len-1] are all zero and a[0] < b.
208 OPENSSL_COMPILE_ASSERT(sizeof(BN_ULONG) <= sizeof(crypto_word_t),
209 crypto_word_t_too_small);
210 crypto_word_t mask = 0;
211 for (size_t i = 1; i < len; i++) {
214 // |mask| is now zero iff a[1..len-1] are all zero.
215 mask = constant_time_is_zero_w(mask);
216 mask &= constant_time_lt_w(a[0], b);
220 int bn_in_range_words(const BN_ULONG *a, BN_ULONG min_inclusive,
221 const BN_ULONG *max_exclusive, size_t len) {
222 crypto_word_t mask = ~bn_less_than_word_mask(a, len, min_inclusive);
223 return mask & bn_less_than_words(a, max_exclusive, len);
226 static int bn_range_to_mask(size_t *out_words, BN_ULONG *out_mask,
227 size_t min_inclusive, const BN_ULONG *max_exclusive,
229 // The magnitude of |max_exclusive| is assumed public.
231 while (words > 0 && max_exclusive[words - 1] == 0) {
235 (words == 1 && max_exclusive[0] <= min_inclusive)) {
236 OPENSSL_PUT_ERROR(BN, BN_R_INVALID_RANGE);
239 BN_ULONG mask = max_exclusive[words - 1];
240 // This sets all bits in |mask| below the most significant bit.
246 #if defined(OPENSSL_64_BIT)
255 int bn_rand_range_words(BN_ULONG *out, BN_ULONG min_inclusive,
256 const BN_ULONG *max_exclusive, size_t len,
257 const uint8_t additional_data[32]) {
258 // This function implements the equivalent of steps 4 through 7 of FIPS 186-4
259 // appendices B.4.2 and B.5.2. When called in those contexts, |max_exclusive|
260 // is n and |min_inclusive| is one.
262 // Compute the bit length of |max_exclusive| (step 1), in terms of a number of
263 // |words| worth of entropy to fill and a mask of bits to clear in the top
267 if (!bn_range_to_mask(&words, &mask, min_inclusive, max_exclusive, len)) {
271 // Fill any unused words with zero.
272 OPENSSL_memset(out + words, 0, (len - words) * sizeof(BN_ULONG));
274 unsigned count = 100;
277 OPENSSL_PUT_ERROR(BN, BN_R_TOO_MANY_ITERATIONS);
281 // Steps 4 and 5. Use |words| and |mask| together to obtain a string of N
282 // bits, where N is the bit length of |max_exclusive|.
283 RAND_bytes_with_additional_data((uint8_t *)out, words * sizeof(BN_ULONG),
285 out[words - 1] &= mask;
287 // If out >= max_exclusive or out < min_inclusive, retry. This implements
288 // the equivalent of steps 6 and 7 without leaking the value of |out|.
289 } while (!bn_in_range_words(out, min_inclusive, max_exclusive, words));
293 int BN_rand_range_ex(BIGNUM *r, BN_ULONG min_inclusive,
294 const BIGNUM *max_exclusive) {
295 static const uint8_t kDefaultAdditionalData[32] = {0};
296 if (!bn_wexpand(r, max_exclusive->width) ||
297 !bn_rand_range_words(r->d, min_inclusive, max_exclusive->d,
298 max_exclusive->width, kDefaultAdditionalData)) {
303 r->width = max_exclusive->width;
307 int bn_rand_secret_range(BIGNUM *r, int *out_is_uniform, BN_ULONG min_inclusive,
308 const BIGNUM *max_exclusive) {
311 if (!bn_range_to_mask(&words, &mask, min_inclusive, max_exclusive->d,
312 max_exclusive->width) ||
313 !bn_wexpand(r, words)) {
319 // The range must be large enough for bit tricks to fix invalid values.
320 if (words == 1 && min_inclusive > mask >> 1) {
321 OPENSSL_PUT_ERROR(BN, BN_R_INVALID_RANGE);
325 // Select a uniform random number with num_bits(max_exclusive) bits.
326 RAND_bytes((uint8_t *)r->d, words * sizeof(BN_ULONG));
327 r->d[words - 1] &= mask;
329 // Check, in constant-time, if the value is in range.
331 bn_in_range_words(r->d, min_inclusive, max_exclusive->d, words);
332 crypto_word_t in_range = *out_is_uniform;
333 in_range = 0 - in_range;
335 // If the value is not in range, force it to be in range.
336 r->d[0] |= constant_time_select_w(in_range, 0, min_inclusive);
337 r->d[words - 1] &= constant_time_select_w(in_range, BN_MASK2, mask >> 1);
338 assert(bn_in_range_words(r->d, min_inclusive, max_exclusive->d, words));
345 int BN_rand_range(BIGNUM *r, const BIGNUM *range) {
346 return BN_rand_range_ex(r, 0, range);
349 int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range) {
350 return BN_rand_range(r, range);