1 /* crypto/bn/bn_rand.c */
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 <stdio.h>
113 #include <time.h>
114 #include "cryptlib.h"
115 #include "bn_lcl.h"
116 #include <openssl/rand.h>
117 #include <openssl/sha.h>
118
bnrand(int pseudorand,BIGNUM * rnd,int bits,int top,int bottom)119 static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
120 {
121 unsigned char *buf=NULL;
122 int ret=0,bit,bytes,mask;
123 time_t tim;
124
125 if (bits == 0)
126 {
127 BN_zero(rnd);
128 return 1;
129 }
130
131 bytes=(bits+7)/8;
132 bit=(bits-1)%8;
133 mask=0xff<<(bit+1);
134
135 buf=(unsigned char *)OPENSSL_malloc(bytes);
136 if (buf == NULL)
137 {
138 BNerr(BN_F_BNRAND,ERR_R_MALLOC_FAILURE);
139 goto err;
140 }
141
142 /* make a random number and set the top and bottom bits */
143 time(&tim);
144 RAND_add(&tim,sizeof(tim),0.0);
145
146 if (pseudorand)
147 {
148 if (RAND_pseudo_bytes(buf, bytes) == -1)
149 goto err;
150 }
151 else
152 {
153 if (RAND_bytes(buf, bytes) <= 0)
154 goto err;
155 }
156
157 #if 1
158 if (pseudorand == 2)
159 {
160 /* generate patterns that are more likely to trigger BN
161 library bugs */
162 int i;
163 unsigned char c;
164
165 for (i = 0; i < bytes; i++)
166 {
167 RAND_pseudo_bytes(&c, 1);
168 if (c >= 128 && i > 0)
169 buf[i] = buf[i-1];
170 else if (c < 42)
171 buf[i] = 0;
172 else if (c < 84)
173 buf[i] = 255;
174 }
175 }
176 #endif
177
178 if (top != -1)
179 {
180 if (top)
181 {
182 if (bit == 0)
183 {
184 buf[0]=1;
185 buf[1]|=0x80;
186 }
187 else
188 {
189 buf[0]|=(3<<(bit-1));
190 }
191 }
192 else
193 {
194 buf[0]|=(1<<bit);
195 }
196 }
197 buf[0] &= ~mask;
198 if (bottom) /* set bottom bit if requested */
199 buf[bytes-1]|=1;
200 if (!BN_bin2bn(buf,bytes,rnd)) goto err;
201 ret=1;
202 err:
203 if (buf != NULL)
204 {
205 OPENSSL_cleanse(buf,bytes);
206 OPENSSL_free(buf);
207 }
208 bn_check_top(rnd);
209 return(ret);
210 }
211
BN_rand(BIGNUM * rnd,int bits,int top,int bottom)212 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
213 {
214 return bnrand(0, rnd, bits, top, bottom);
215 }
216
BN_pseudo_rand(BIGNUM * rnd,int bits,int top,int bottom)217 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
218 {
219 return bnrand(1, rnd, bits, top, bottom);
220 }
221
222 #if 1
BN_bntest_rand(BIGNUM * rnd,int bits,int top,int bottom)223 int BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom)
224 {
225 return bnrand(2, rnd, bits, top, bottom);
226 }
227 #endif
228
229
230 /* random number r: 0 <= r < range */
bn_rand_range(int pseudo,BIGNUM * r,const BIGNUM * range)231 static int bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range)
232 {
233 int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand;
234 int n;
235 int count = 100;
236
237 if (range->neg || BN_is_zero(range))
238 {
239 BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE);
240 return 0;
241 }
242
243 n = BN_num_bits(range); /* n > 0 */
244
245 /* BN_is_bit_set(range, n - 1) always holds */
246
247 if (n == 1)
248 BN_zero(r);
249 else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3))
250 {
251 /* range = 100..._2,
252 * so 3*range (= 11..._2) is exactly one bit longer than range */
253 do
254 {
255 if (!bn_rand(r, n + 1, -1, 0)) return 0;
256 /* If r < 3*range, use r := r MOD range
257 * (which is either r, r - range, or r - 2*range).
258 * Otherwise, iterate once more.
259 * Since 3*range = 11..._2, each iteration succeeds with
260 * probability >= .75. */
261 if (BN_cmp(r ,range) >= 0)
262 {
263 if (!BN_sub(r, r, range)) return 0;
264 if (BN_cmp(r, range) >= 0)
265 if (!BN_sub(r, r, range)) return 0;
266 }
267
268 if (!--count)
269 {
270 BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
271 return 0;
272 }
273
274 }
275 while (BN_cmp(r, range) >= 0);
276 }
277 else
278 {
279 do
280 {
281 /* range = 11..._2 or range = 101..._2 */
282 if (!bn_rand(r, n, -1, 0)) return 0;
283
284 if (!--count)
285 {
286 BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
287 return 0;
288 }
289 }
290 while (BN_cmp(r, range) >= 0);
291 }
292
293 bn_check_top(r);
294 return 1;
295 }
296
297
BN_rand_range(BIGNUM * r,const BIGNUM * range)298 int BN_rand_range(BIGNUM *r, const BIGNUM *range)
299 {
300 return bn_rand_range(0, r, range);
301 }
302
BN_pseudo_rand_range(BIGNUM * r,const BIGNUM * range)303 int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range)
304 {
305 return bn_rand_range(1, r, range);
306 }
307
308 #ifndef OPENSSL_NO_SHA512
309 /* BN_generate_dsa_nonce generates a random number 0 <= out < range. Unlike
310 * BN_rand_range, it also includes the contents of |priv| and |message| in the
311 * generation so that an RNG failure isn't fatal as long as |priv| remains
312 * secret. This is intended for use in DSA and ECDSA where an RNG weakness
313 * leads directly to private key exposure unless this function is used. */
BN_generate_dsa_nonce(BIGNUM * out,const BIGNUM * range,const BIGNUM * priv,const unsigned char * message,size_t message_len,BN_CTX * ctx)314 int BN_generate_dsa_nonce(BIGNUM *out, const BIGNUM *range, const BIGNUM* priv,
315 const unsigned char *message, size_t message_len,
316 BN_CTX *ctx)
317 {
318 SHA512_CTX sha;
319 /* We use 512 bits of random data per iteration to
320 * ensure that we have at least |range| bits of randomness. */
321 unsigned char random_bytes[64];
322 unsigned char digest[SHA512_DIGEST_LENGTH];
323 unsigned done, todo;
324 /* We generate |range|+8 bytes of random output. */
325 const unsigned num_k_bytes = BN_num_bytes(range) + 8;
326 unsigned char private_bytes[96];
327 unsigned char *k_bytes;
328 int ret = 0;
329
330 k_bytes = OPENSSL_malloc(num_k_bytes);
331 if (!k_bytes)
332 goto err;
333
334 /* We copy |priv| into a local buffer to avoid exposing its length. */
335 todo = sizeof(priv->d[0])*priv->top;
336 if (todo > sizeof(private_bytes))
337 {
338 /* No reasonable DSA or ECDSA key should have a private key
339 * this large and we don't handle this case in order to avoid
340 * leaking the length of the private key. */
341 BNerr(BN_F_BN_GENERATE_DSA_NONCE, BN_R_PRIVATE_KEY_TOO_LARGE);
342 goto err;
343 }
344 memcpy(private_bytes, priv->d, todo);
345 memset(private_bytes + todo, 0, sizeof(private_bytes) - todo);
346
347 for (done = 0; done < num_k_bytes;) {
348 if (RAND_bytes(random_bytes, sizeof(random_bytes)) != 1)
349 goto err;
350 SHA512_Init(&sha);
351 SHA512_Update(&sha, &done, sizeof(done));
352 SHA512_Update(&sha, private_bytes, sizeof(private_bytes));
353 SHA512_Update(&sha, message, message_len);
354 SHA512_Update(&sha, random_bytes, sizeof(random_bytes));
355 SHA512_Final(digest, &sha);
356
357 todo = num_k_bytes - done;
358 if (todo > SHA512_DIGEST_LENGTH)
359 todo = SHA512_DIGEST_LENGTH;
360 memcpy(k_bytes + done, digest, todo);
361 done += todo;
362 }
363
364 if (!BN_bin2bn(k_bytes, num_k_bytes, out))
365 goto err;
366 if (BN_mod(out, out, range, ctx) != 1)
367 goto err;
368 ret = 1;
369
370 err:
371 if (k_bytes)
372 OPENSSL_free(k_bytes);
373 return ret;
374 }
375 #endif /* OPENSSL_NO_SHA512 */
376