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bn_rand.c
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1 /* crypto/bn/bn_rand.c */
2 /* Copyright (C) 1995-1998 Eric Young ([email protected])
3  * All rights reserved.
4  *
5  * This package is an SSL implementation written
6  * by Eric Young ([email protected]).
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 ([email protected]).
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 ([email protected])"
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 ([email protected])"
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  * [email protected].
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  * ([email protected]). This product includes software written by Tim
108  * Hudson ([email protected]).
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 
118 static int bnrand(int pseudorand, BIGNUM *rnd, int bits, int top, int bottom)
119  {
120  unsigned char *buf=NULL;
121  int ret=0,bit,bytes,mask;
122  time_t tim;
123 
124  if (bits == 0)
125  {
126  BN_zero(rnd);
127  return 1;
128  }
129 
130  bytes=(bits+7)/8;
131  bit=(bits-1)%8;
132  mask=0xff<<(bit+1);
133 
134  buf=(unsigned char *)OPENSSL_malloc(bytes);
135  if (buf == NULL)
136  {
137  BNerr(BN_F_BNRAND,ERR_R_MALLOC_FAILURE);
138  goto err;
139  }
140 
141  /* make a random number and set the top and bottom bits */
142  time(&tim);
143  RAND_add(&tim,sizeof(tim),0.0);
144 
145  if (pseudorand)
146  {
147  if (RAND_pseudo_bytes(buf, bytes) == -1)
148  goto err;
149  }
150  else
151  {
152  if (RAND_bytes(buf, bytes) <= 0)
153  goto err;
154  }
155 
156 #if 1
157  if (pseudorand == 2)
158  {
159  /* generate patterns that are more likely to trigger BN
160  library bugs */
161  int i;
162  unsigned char c;
163 
164  for (i = 0; i < bytes; i++)
165  {
166  RAND_pseudo_bytes(&c, 1);
167  if (c >= 128 && i > 0)
168  buf[i] = buf[i-1];
169  else if (c < 42)
170  buf[i] = 0;
171  else if (c < 84)
172  buf[i] = 255;
173  }
174  }
175 #endif
176 
177  if (top != -1)
178  {
179  if (top)
180  {
181  if (bit == 0)
182  {
183  buf[0]=1;
184  buf[1]|=0x80;
185  }
186  else
187  {
188  buf[0]|=(3<<(bit-1));
189  }
190  }
191  else
192  {
193  buf[0]|=(1<<bit);
194  }
195  }
196  buf[0] &= ~mask;
197  if (bottom) /* set bottom bit if requested */
198  buf[bytes-1]|=1;
199  if (!BN_bin2bn(buf,bytes,rnd)) goto err;
200  ret=1;
201 err:
202  if (buf != NULL)
203  {
204  OPENSSL_cleanse(buf,bytes);
205  OPENSSL_free(buf);
206  }
207  bn_check_top(rnd);
208  return(ret);
209  }
210 
211 int BN_rand(BIGNUM *rnd, int bits, int top, int bottom)
212  {
213  return bnrand(0, rnd, bits, top, bottom);
214  }
215 
216 int BN_pseudo_rand(BIGNUM *rnd, int bits, int top, int bottom)
217  {
218  return bnrand(1, rnd, bits, top, bottom);
219  }
220 
221 #if 1
222 int BN_bntest_rand(BIGNUM *rnd, int bits, int top, int bottom)
223  {
224  return bnrand(2, rnd, bits, top, bottom);
225  }
226 #endif
227 
228 
229 /* random number r: 0 <= r < range */
230 static int bn_rand_range(int pseudo, BIGNUM *r, const BIGNUM *range)
231  {
232  int (*bn_rand)(BIGNUM *, int, int, int) = pseudo ? BN_pseudo_rand : BN_rand;
233  int n;
234  int count = 100;
235 
236  if (range->neg || BN_is_zero(range))
237  {
238  BNerr(BN_F_BN_RAND_RANGE, BN_R_INVALID_RANGE);
239  return 0;
240  }
241 
242  n = BN_num_bits(range); /* n > 0 */
243 
244  /* BN_is_bit_set(range, n - 1) always holds */
245 
246  if (n == 1)
247  BN_zero(r);
248  else if (!BN_is_bit_set(range, n - 2) && !BN_is_bit_set(range, n - 3))
249  {
250  /* range = 100..._2,
251  * so 3*range (= 11..._2) is exactly one bit longer than range */
252  do
253  {
254  if (!bn_rand(r, n + 1, -1, 0)) return 0;
255  /* If r < 3*range, use r := r MOD range
256  * (which is either r, r - range, or r - 2*range).
257  * Otherwise, iterate once more.
258  * Since 3*range = 11..._2, each iteration succeeds with
259  * probability >= .75. */
260  if (BN_cmp(r ,range) >= 0)
261  {
262  if (!BN_sub(r, r, range)) return 0;
263  if (BN_cmp(r, range) >= 0)
264  if (!BN_sub(r, r, range)) return 0;
265  }
266 
267  if (!--count)
268  {
269  BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
270  return 0;
271  }
272 
273  }
274  while (BN_cmp(r, range) >= 0);
275  }
276  else
277  {
278  do
279  {
280  /* range = 11..._2 or range = 101..._2 */
281  if (!bn_rand(r, n, -1, 0)) return 0;
282 
283  if (!--count)
284  {
285  BNerr(BN_F_BN_RAND_RANGE, BN_R_TOO_MANY_ITERATIONS);
286  return 0;
287  }
288  }
289  while (BN_cmp(r, range) >= 0);
290  }
291 
292  bn_check_top(r);
293  return 1;
294  }
295 
296 
297 int BN_rand_range(BIGNUM *r, const BIGNUM *range)
298  {
299  return bn_rand_range(0, r, range);
300  }
301 
302 int BN_pseudo_rand_range(BIGNUM *r, const BIGNUM *range)
303  {
304  return bn_rand_range(1, r, range);
305  }
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