1 /* crypto/bn/bn_prime.c */
2 /* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
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.
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).
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.
23 * Redistribution and use in source and binary forms, with or without
24 * modification, are permitted provided that the following conditions
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)"
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
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.]
58 /* ====================================================================
59 * Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved.
61 * Redistribution and use in source and binary forms, with or without
62 * modification, are permitted provided that the following conditions
65 * 1. Redistributions of source code must retain the above copyright
66 * notice, this list of conditions and the following disclaimer.
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
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/)"
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.
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.
87 * 6. Redistributions of any form whatsoever must retain the following
89 * "This product includes software developed by the OpenSSL Project
90 * for use in the OpenSSL Toolkit (http://www.openssl.org/)"
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 * ====================================================================
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).
114 #include "cryptlib.h"
116 #include <openssl/rand.h>
118 /* NB: these functions have been "upgraded", the deprecated versions (which are
119 * compatibility wrappers using these functions) are in bn_depr.c.
123 /* The quick sieve algorithm approach to weeding out primes is
124 * Philip Zimmermann's, as implemented in PGP. I have had a read of
125 * his comments and implemented my own version.
127 #include "bn_prime.h"
129 static int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1,
130 const BIGNUM *a1_odd, int k, BN_CTX *ctx, BN_MONT_CTX *mont);
131 static int probable_prime(BIGNUM *rnd, int bits);
132 static int probable_prime_dh_safe(BIGNUM *rnd, int bits,
133 const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx);
135 static const int prime_offsets[480] = {
136 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89,
137 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167,
138 169, 173, 179, 181, 191, 193, 197, 199, 211, 221, 223, 227, 229, 233, 239,
139 241, 247, 251, 257, 263, 269, 271, 277, 281, 283, 289, 293, 299, 307, 311,
140 313, 317, 323, 331, 337, 347, 349, 353, 359, 361, 367, 373, 377, 379, 383,
141 389, 391, 397, 401, 403, 409, 419, 421, 431, 433, 437, 439, 443, 449, 457,
142 461, 463, 467, 479, 481, 487, 491, 493, 499, 503, 509, 521, 523, 527, 529,
143 533, 541, 547, 551, 557, 559, 563, 569, 571, 577, 587, 589, 593, 599, 601,
144 607, 611, 613, 617, 619, 629, 631, 641, 643, 647, 653, 659, 661, 667, 673,
145 677, 683, 689, 691, 697, 701, 703, 709, 713, 719, 727, 731, 733, 739, 743,
146 751, 757, 761, 767, 769, 773, 779, 787, 793, 797, 799, 809, 811, 817, 821,
147 823, 827, 829, 839, 841, 851, 853, 857, 859, 863, 871, 877, 881, 883, 887,
148 893, 899, 901, 907, 911, 919, 923, 929, 937, 941, 943, 947, 949, 953, 961,
149 967, 971, 977, 983, 989, 991, 997, 1003, 1007, 1009, 1013, 1019, 1021, 1027,
150 1031, 1033, 1037, 1039, 1049, 1051, 1061, 1063, 1069, 1073, 1079, 1081,
151 1087, 1091, 1093, 1097, 1103, 1109, 1117, 1121, 1123, 1129, 1139, 1147,
152 1151, 1153, 1157, 1159, 1163, 1171, 1181, 1187, 1189, 1193, 1201, 1207,
153 1213, 1217, 1219, 1223, 1229, 1231, 1237, 1241, 1247, 1249, 1259, 1261,
154 1271, 1273, 1277, 1279, 1283, 1289, 1291, 1297, 1301, 1303, 1307, 1313,
155 1319, 1321, 1327, 1333, 1339, 1343, 1349, 1357, 1361, 1363, 1367, 1369,
156 1373, 1381, 1387, 1391, 1399, 1403, 1409, 1411, 1417, 1423, 1427, 1429,
157 1433, 1439, 1447, 1451, 1453, 1457, 1459, 1469, 1471, 1481, 1483, 1487,
158 1489, 1493, 1499, 1501, 1511, 1513, 1517, 1523, 1531, 1537, 1541, 1543,
159 1549, 1553, 1559, 1567, 1571, 1577, 1579, 1583, 1591, 1597, 1601, 1607,
160 1609, 1613, 1619, 1621, 1627, 1633, 1637, 1643, 1649, 1651, 1657, 1663,
161 1667, 1669, 1679, 1681, 1691, 1693, 1697, 1699, 1703, 1709, 1711, 1717,
162 1721, 1723, 1733, 1739, 1741, 1747, 1751, 1753, 1759, 1763, 1769, 1777,
163 1781, 1783, 1787, 1789, 1801, 1807, 1811, 1817, 1819, 1823, 1829, 1831,
164 1843, 1847, 1849, 1853, 1861, 1867, 1871, 1873, 1877, 1879, 1889, 1891,
165 1901, 1907, 1909, 1913, 1919, 1921, 1927, 1931, 1933, 1937, 1943, 1949,
166 1951, 1957, 1961, 1963, 1973, 1979, 1987, 1993, 1997, 1999, 2003, 2011,
167 2017, 2021, 2027, 2029, 2033, 2039, 2041, 2047, 2053, 2059, 2063, 2069,
168 2071, 2077, 2081, 2083, 2087, 2089, 2099, 2111, 2113, 2117, 2119, 2129,
169 2131, 2137, 2141, 2143, 2147, 2153, 2159, 2161, 2171, 2173, 2179, 2183,
170 2197, 2201, 2203, 2207, 2209, 2213, 2221, 2227, 2231, 2237, 2239, 2243,
171 2249, 2251, 2257, 2263, 2267, 2269, 2273, 2279, 2281, 2287, 2291, 2293,
173 static const int prime_offset_count = 480;
174 static const int prime_multiplier = 2310;
175 static const int prime_multiplier_bits = 11;
176 static const int first_prime_index = 5;
178 int BN_GENCB_call(BN_GENCB *cb, int a, int b)
180 /* No callback means continue */
185 /* Deprecated-style callbacks */
188 cb->cb.cb_1(a, b, cb->arg);
191 /* New-style callbacks */
192 return cb->cb.cb_2(a, b, cb);
196 /* Unrecognised callback type */
200 int BN_generate_prime_ex(BIGNUM *ret, int bits, int safe,
201 const BIGNUM *add, const BIGNUM *rem, BN_GENCB *cb)
207 int checks = BN_prime_checks_for_size(bits);
211 /* There are no prime numbers this small. */
212 BNerr(BN_F_BN_GENERATE_PRIME_EX, BN_R_BITS_TOO_SMALL);
215 else if (bits == 2 && safe)
217 /* The smallest safe prime (7) is three bits. */
218 BNerr(BN_F_BN_GENERATE_PRIME_EX, BN_R_BITS_TOO_SMALL);
223 if (ctx == NULL) goto err;
228 /* make a random number and set the top and bottom bits */
231 if (!probable_prime(ret,bits)) goto err;
237 if (!probable_prime_dh_safe(ret,bits,add,rem,ctx))
242 if (!bn_probable_prime_dh(ret,bits,add,rem,ctx))
246 /* if (BN_mod_word(ret,(BN_ULONG)3) == 1) goto loop; */
247 if(!BN_GENCB_call(cb, 0, c1++))
253 i=BN_is_prime_fasttest_ex(ret,checks,ctx,0,cb);
254 if (i == -1) goto err;
255 if (i == 0) goto loop;
259 /* for "safe prime" generation,
260 * check that (p-1)/2 is prime.
261 * Since a prime is odd, We just
262 * need to divide by 2 */
263 if (!BN_rshift1(t,ret)) goto err;
265 for (i=0; i<checks; i++)
267 j=BN_is_prime_fasttest_ex(ret,1,ctx,0,cb);
268 if (j == -1) goto err;
269 if (j == 0) goto loop;
271 j=BN_is_prime_fasttest_ex(t,1,ctx,0,cb);
272 if (j == -1) goto err;
273 if (j == 0) goto loop;
275 if(!BN_GENCB_call(cb, 2, c1-1))
277 /* We have a safe prime test pass */
280 /* we have a prime :-) */
292 int BN_is_prime_ex(const BIGNUM *a, int checks, BN_CTX *ctx_passed, BN_GENCB *cb)
294 return BN_is_prime_fasttest_ex(a, checks, ctx_passed, 0, cb);
297 int BN_is_prime_fasttest_ex(const BIGNUM *a, int checks, BN_CTX *ctx_passed,
298 int do_trial_division, BN_GENCB *cb)
303 BIGNUM *A1, *A1_odd, *check; /* taken from ctx */
304 BN_MONT_CTX *mont = NULL;
305 const BIGNUM *A = NULL;
307 if (BN_cmp(a, BN_value_one()) <= 0)
310 if (checks == BN_prime_checks)
311 checks = BN_prime_checks_for_size(BN_num_bits(a));
313 /* first look for small factors */
315 /* a is even => a is prime if and only if a == 2 */
316 return BN_is_word(a, 2);
317 if (do_trial_division)
319 for (i = 1; i < NUMPRIMES; i++)
320 if (BN_mod_word(a, primes[i]) == 0)
322 if(!BN_GENCB_call(cb, 1, -1))
326 if (ctx_passed != NULL)
329 if ((ctx=BN_CTX_new()) == NULL)
337 if ((t = BN_CTX_get(ctx)) == NULL) goto err;
344 A1 = BN_CTX_get(ctx);
345 A1_odd = BN_CTX_get(ctx);
346 check = BN_CTX_get(ctx);
347 if (check == NULL) goto err;
349 /* compute A1 := A - 1 */
352 if (!BN_sub_word(A1, 1))
360 /* write A1 as A1_odd * 2^k */
362 while (!BN_is_bit_set(A1, k))
364 if (!BN_rshift(A1_odd, A1, k))
367 /* Montgomery setup for computations mod A */
368 mont = BN_MONT_CTX_new();
371 if (!BN_MONT_CTX_set(mont, A, ctx))
374 for (i = 0; i < checks; i++)
376 if (!BN_pseudo_rand_range(check, A1))
378 if (!BN_add_word(check, 1))
380 /* now 1 <= check < A */
382 j = witness(check, A, A1, A1_odd, k, ctx, mont);
383 if (j == -1) goto err;
389 if(!BN_GENCB_call(cb, 1, i))
397 if (ctx_passed == NULL)
401 BN_MONT_CTX_free(mont);
406 int bn_probable_prime_dh_retry(BIGNUM *rnd, int bits, BN_CTX *ctx)
412 if (!BN_rand(rnd, bits, 0, 1)) goto err;
414 /* we now have a random number 'rand' to test. */
416 for (i = 1; i < NUMPRIMES; i++)
418 /* check that rnd is a prime */
419 if (BN_mod_word(rnd, (BN_ULONG)primes[i]) <= 1)
431 int bn_probable_prime_dh_coprime(BIGNUM *rnd, int bits, BN_CTX *ctx)
434 BIGNUM *offset_index;
435 BIGNUM *offset_count;
438 OPENSSL_assert(bits > prime_multiplier_bits);
441 if ((offset_index = BN_CTX_get(ctx)) == NULL) goto err;
442 if ((offset_count = BN_CTX_get(ctx)) == NULL) goto err;
444 BN_add_word(offset_count, prime_offset_count);
447 if (!BN_rand(rnd, bits - prime_multiplier_bits, 0, 1)) goto err;
448 if (!BN_rand_range(offset_index, offset_count)) goto err;
450 BN_mul_word(rnd, prime_multiplier);
451 BN_add_word(rnd, prime_offsets[BN_get_word(offset_index)]);
453 /* we now have a random number 'rand' to test. */
456 for (i = first_prime_index; i < NUMPRIMES; i++)
458 /* check that rnd is a prime */
459 if (BN_mod_word(rnd, (BN_ULONG)primes[i]) <= 1)
472 static int witness(BIGNUM *w, const BIGNUM *a, const BIGNUM *a1,
473 const BIGNUM *a1_odd, int k, BN_CTX *ctx, BN_MONT_CTX *mont)
475 if (!BN_mod_exp_mont(w, w, a1_odd, a, ctx, mont)) /* w := w^a1_odd mod a */
478 return 0; /* probably prime */
479 if (BN_cmp(w, a1) == 0)
480 return 0; /* w == -1 (mod a), 'a' is probably prime */
483 if (!BN_mod_mul(w, w, w, a, ctx)) /* w := w^2 mod a */
486 return 1; /* 'a' is composite, otherwise a previous 'w' would
487 * have been == -1 (mod 'a') */
488 if (BN_cmp(w, a1) == 0)
489 return 0; /* w == -1 (mod a), 'a' is probably prime */
491 /* If we get here, 'w' is the (a-1)/2-th power of the original 'w',
492 * and it is neither -1 nor +1 -- so 'a' cannot be prime */
497 static int probable_prime(BIGNUM *rnd, int bits)
500 prime_t mods[NUMPRIMES];
502 BN_ULONG maxdelta = BN_MASK2 - primes[NUMPRIMES-1];
503 char is_single_word = bits <= BN_BITS2;
506 if (!BN_rand(rnd,bits,1,1)) return(0);
507 /* we now have a random number 'rnd' to test. */
508 for (i=1; i<NUMPRIMES; i++)
509 mods[i]=(prime_t)BN_mod_word(rnd,(BN_ULONG)primes[i]);
510 /* If bits is so small that it fits into a single word then we
511 * additionally don't want to exceed that many bits. */
514 BN_ULONG size_limit = (((BN_ULONG) 1) << bits) - BN_get_word(rnd) - 1;
515 if (size_limit < maxdelta)
516 maxdelta = size_limit;
522 BN_ULONG rnd_word = BN_get_word(rnd);
524 /* In the case that the candidate prime is a single word then
526 * 1) It's greater than primes[i] because we shouldn't reject
527 * 3 as being a prime number because it's a multiple of
529 * 2) That it's not a multiple of a known prime. We don't
530 * check that rnd-1 is also coprime to all the known
531 * primes because there aren't many small primes where
533 for (i=1; i<NUMPRIMES && primes[i]<rnd_word; i++)
535 if ((mods[i]+delta)%primes[i] == 0)
538 if (delta > maxdelta) goto again;
545 for (i=1; i<NUMPRIMES; i++)
547 /* check that rnd is not a prime and also
548 * that gcd(rnd-1,primes) == 1 (except for 2) */
549 if (((mods[i]+delta)%primes[i]) <= 1)
552 if (delta > maxdelta) goto again;
557 if (!BN_add_word(rnd,delta)) return(0);
558 if (BN_num_bits(rnd) != bits)
564 int bn_probable_prime_dh(BIGNUM *rnd, int bits,
565 const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx)
571 if ((t1 = BN_CTX_get(ctx)) == NULL) goto err;
573 if (!BN_rand(rnd,bits,0,1)) goto err;
575 /* we need ((rnd-rem) % add) == 0 */
577 if (!BN_mod(t1,rnd,add,ctx)) goto err;
578 if (!BN_sub(rnd,rnd,t1)) goto err;
580 { if (!BN_add_word(rnd,1)) goto err; }
582 { if (!BN_add(rnd,rnd,rem)) goto err; }
584 /* we now have a random number 'rand' to test. */
587 for (i=1; i<NUMPRIMES; i++)
589 /* check that rnd is a prime */
590 if (BN_mod_word(rnd,(BN_ULONG)primes[i]) <= 1)
592 if (!BN_add(rnd,rnd,add)) goto err;
604 static int probable_prime_dh_safe(BIGNUM *p, int bits, const BIGNUM *padd,
605 const BIGNUM *rem, BN_CTX *ctx)
612 t1 = BN_CTX_get(ctx);
614 qadd = BN_CTX_get(ctx);
615 if (qadd == NULL) goto err;
617 if (!BN_rshift1(qadd,padd)) goto err;
619 if (!BN_rand(q,bits,0,1)) goto err;
621 /* we need ((rnd-rem) % add) == 0 */
622 if (!BN_mod(t1,q,qadd,ctx)) goto err;
623 if (!BN_sub(q,q,t1)) goto err;
625 { if (!BN_add_word(q,1)) goto err; }
628 if (!BN_rshift1(t1,rem)) goto err;
629 if (!BN_add(q,q,t1)) goto err;
632 /* we now have a random number 'rand' to test. */
633 if (!BN_lshift1(p,q)) goto err;
634 if (!BN_add_word(p,1)) goto err;
637 for (i=1; i<NUMPRIMES; i++)
639 /* check that p and q are prime */
640 /* check that for p and q
641 * gcd(p-1,primes) == 1 (except for 2) */
642 if ((BN_mod_word(p,(BN_ULONG)primes[i]) == 0) ||
643 (BN_mod_word(q,(BN_ULONG)primes[i]) == 0))
645 if (!BN_add(p,p,padd)) goto err;
646 if (!BN_add(q,q,qadd)) goto err;