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boringssl/crypto/fipsmodule/bn/prime.c
David Benjamin 97ac45e2f7 Change the order of GCD and trial division. 
RSA key generation currently does the GCD check before the primality
test, in hopes of discarding things invalid by other means before
running the expensive primality check.

However, GCD is about to get a bit more expensive to clear the timing
leak, and the trial division part of primality testing is quite fast.
Thus, split that portion out via a new bn_is_obviously_composite and
call it before GCD.

Median of 29 RSA keygens: 0m0.252s -> 0m0.207s
(Accuracy beyond 0.1s is questionable.)

Bug: 238
Change-Id: I3999771fb73cca16797cab9332d14c4ebeb02046
Reviewed-on: https://boringssl-review.googlesource.com/26366
Reviewed-by: Adam Langley <alangley@gmail.com>
2018-03-30 19:53:06 +00:00

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/* Copyright (C) 1995-1998 Eric Young (eay@cryptsoft.com)
* All rights reserved.
*
* This package is an SSL implementation written
* by Eric Young (eay@cryptsoft.com).
* The implementation was written so as to conform with Netscapes SSL.
*
* This library is free for commercial and non-commercial use as long as
* the following conditions are aheared to. The following conditions
* apply to all code found in this distribution, be it the RC4, RSA,
* lhash, DES, etc., code; not just the SSL code. The SSL documentation
* included with this distribution is covered by the same copyright terms
* except that the holder is Tim Hudson (tjh@cryptsoft.com).
*
* Copyright remains Eric Young's, and as such any Copyright notices in
* the code are not to be removed.
* If this package is used in a product, Eric Young should be given attribution
* as the author of the parts of the library used.
* This can be in the form of a textual message at program startup or
* in documentation (online or textual) provided with the package.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* "This product includes cryptographic software written by
* Eric Young (eay@cryptsoft.com)"
* The word 'cryptographic' can be left out if the rouines from the library
* being used are not cryptographic related :-).
* 4. If you include any Windows specific code (or a derivative thereof) from
* the apps directory (application code) you must include an acknowledgement:
* "This product includes software written by Tim Hudson (tjh@cryptsoft.com)"
*
* THIS SOFTWARE IS PROVIDED BY ERIC YOUNG ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* The licence and distribution terms for any publically available version or
* derivative of this code cannot be changed. i.e. this code cannot simply be
* copied and put under another distribution licence
* [including the GNU Public Licence.]
*/
/* ====================================================================
* Copyright (c) 1998-2001 The OpenSSL Project. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
*
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* 3. All advertising materials mentioning features or use of this
* software must display the following acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit. (http://www.openssl.org/)"
*
* 4. The names "OpenSSL Toolkit" and "OpenSSL Project" must not be used to
* endorse or promote products derived from this software without
* prior written permission. For written permission, please contact
* openssl-core@openssl.org.
*
* 5. Products derived from this software may not be called "OpenSSL"
* nor may "OpenSSL" appear in their names without prior written
* permission of the OpenSSL Project.
*
* 6. Redistributions of any form whatsoever must retain the following
* acknowledgment:
* "This product includes software developed by the OpenSSL Project
* for use in the OpenSSL Toolkit (http://www.openssl.org/)"
*
* THIS SOFTWARE IS PROVIDED BY THE OpenSSL PROJECT ``AS IS'' AND ANY
* EXPRESSED OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE OpenSSL PROJECT OR
* ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
* SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
* NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
* LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
* OF THE POSSIBILITY OF SUCH DAMAGE.
* ====================================================================
*
* This product includes cryptographic software written by Eric Young
* (eay@cryptsoft.com). This product includes software written by Tim
* Hudson (tjh@cryptsoft.com). */
#include <openssl/bn.h>
#include <openssl/err.h>
#include <openssl/mem.h>
#include "internal.h"
#include "../../internal.h"
// The quick sieve algorithm approach to weeding out primes is Philip
// Zimmermann's, as implemented in PGP. I have had a read of his comments and
// implemented my own version.
#define NUMPRIMES 2048
// primes contains all the primes that fit into a uint16_t.
static const uint16_t primes[NUMPRIMES] = {
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31,
37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79,
83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137,
139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193,
197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257,
263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317,
331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389,
397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457,
461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523,
541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601,
607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661,
673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743,
751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823,
827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887,
907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977,
983, 991, 997, 1009, 1013, 1019, 1021, 1031, 1033, 1039, 1049,
1051, 1061, 1063, 1069, 1087, 1091, 1093, 1097, 1103, 1109, 1117,
1123, 1129, 1151, 1153, 1163, 1171, 1181, 1187, 1193, 1201, 1213,
1217, 1223, 1229, 1231, 1237, 1249, 1259, 1277, 1279, 1283, 1289,
1291, 1297, 1301, 1303, 1307, 1319, 1321, 1327, 1361, 1367, 1373,
1381, 1399, 1409, 1423, 1427, 1429, 1433, 1439, 1447, 1451, 1453,
1459, 1471, 1481, 1483, 1487, 1489, 1493, 1499, 1511, 1523, 1531,
1543, 1549, 1553, 1559, 1567, 1571, 1579, 1583, 1597, 1601, 1607,
1609, 1613, 1619, 1621, 1627, 1637, 1657, 1663, 1667, 1669, 1693,
1697, 1699, 1709, 1721, 1723, 1733, 1741, 1747, 1753, 1759, 1777,
1783, 1787, 1789, 1801, 1811, 1823, 1831, 1847, 1861, 1867, 1871,
1873, 1877, 1879, 1889, 1901, 1907, 1913, 1931, 1933, 1949, 1951,
1973, 1979, 1987, 1993, 1997, 1999, 2003, 2011, 2017, 2027, 2029,
2039, 2053, 2063, 2069, 2081, 2083, 2087, 2089, 2099, 2111, 2113,
2129, 2131, 2137, 2141, 2143, 2153, 2161, 2179, 2203, 2207, 2213,
2221, 2237, 2239, 2243, 2251, 2267, 2269, 2273, 2281, 2287, 2293,
2297, 2309, 2311, 2333, 2339, 2341, 2347, 2351, 2357, 2371, 2377,
2381, 2383, 2389, 2393, 2399, 2411, 2417, 2423, 2437, 2441, 2447,
2459, 2467, 2473, 2477, 2503, 2521, 2531, 2539, 2543, 2549, 2551,
2557, 2579, 2591, 2593, 2609, 2617, 2621, 2633, 2647, 2657, 2659,
2663, 2671, 2677, 2683, 2687, 2689, 2693, 2699, 2707, 2711, 2713,
2719, 2729, 2731, 2741, 2749, 2753, 2767, 2777, 2789, 2791, 2797,
2801, 2803, 2819, 2833, 2837, 2843, 2851, 2857, 2861, 2879, 2887,
2897, 2903, 2909, 2917, 2927, 2939, 2953, 2957, 2963, 2969, 2971,
2999, 3001, 3011, 3019, 3023, 3037, 3041, 3049, 3061, 3067, 3079,
3083, 3089, 3109, 3119, 3121, 3137, 3163, 3167, 3169, 3181, 3187,
3191, 3203, 3209, 3217, 3221, 3229, 3251, 3253, 3257, 3259, 3271,
3299, 3301, 3307, 3313, 3319, 3323, 3329, 3331, 3343, 3347, 3359,
3361, 3371, 3373, 3389, 3391, 3407, 3413, 3433, 3449, 3457, 3461,
3463, 3467, 3469, 3491, 3499, 3511, 3517, 3527, 3529, 3533, 3539,
3541, 3547, 3557, 3559, 3571, 3581, 3583, 3593, 3607, 3613, 3617,
3623, 3631, 3637, 3643, 3659, 3671, 3673, 3677, 3691, 3697, 3701,
3709, 3719, 3727, 3733, 3739, 3761, 3767, 3769, 3779, 3793, 3797,
3803, 3821, 3823, 3833, 3847, 3851, 3853, 3863, 3877, 3881, 3889,
3907, 3911, 3917, 3919, 3923, 3929, 3931, 3943, 3947, 3967, 3989,
4001, 4003, 4007, 4013, 4019, 4021, 4027, 4049, 4051, 4057, 4073,
4079, 4091, 4093, 4099, 4111, 4127, 4129, 4133, 4139, 4153, 4157,
4159, 4177, 4201, 4211, 4217, 4219, 4229, 4231, 4241, 4243, 4253,
4259, 4261, 4271, 4273, 4283, 4289, 4297, 4327, 4337, 4339, 4349,
4357, 4363, 4373, 4391, 4397, 4409, 4421, 4423, 4441, 4447, 4451,
4457, 4463, 4481, 4483, 4493, 4507, 4513, 4517, 4519, 4523, 4547,
4549, 4561, 4567, 4583, 4591, 4597, 4603, 4621, 4637, 4639, 4643,
4649, 4651, 4657, 4663, 4673, 4679, 4691, 4703, 4721, 4723, 4729,
4733, 4751, 4759, 4783, 4787, 4789, 4793, 4799, 4801, 4813, 4817,
4831, 4861, 4871, 4877, 4889, 4903, 4909, 4919, 4931, 4933, 4937,
4943, 4951, 4957, 4967, 4969, 4973, 4987, 4993, 4999, 5003, 5009,
5011, 5021, 5023, 5039, 5051, 5059, 5077, 5081, 5087, 5099, 5101,
5107, 5113, 5119, 5147, 5153, 5167, 5171, 5179, 5189, 5197, 5209,
5227, 5231, 5233, 5237, 5261, 5273, 5279, 5281, 5297, 5303, 5309,
5323, 5333, 5347, 5351, 5381, 5387, 5393, 5399, 5407, 5413, 5417,
5419, 5431, 5437, 5441, 5443, 5449, 5471, 5477, 5479, 5483, 5501,
5503, 5507, 5519, 5521, 5527, 5531, 5557, 5563, 5569, 5573, 5581,
5591, 5623, 5639, 5641, 5647, 5651, 5653, 5657, 5659, 5669, 5683,
5689, 5693, 5701, 5711, 5717, 5737, 5741, 5743, 5749, 5779, 5783,
5791, 5801, 5807, 5813, 5821, 5827, 5839, 5843, 5849, 5851, 5857,
5861, 5867, 5869, 5879, 5881, 5897, 5903, 5923, 5927, 5939, 5953,
5981, 5987, 6007, 6011, 6029, 6037, 6043, 6047, 6053, 6067, 6073,
6079, 6089, 6091, 6101, 6113, 6121, 6131, 6133, 6143, 6151, 6163,
6173, 6197, 6199, 6203, 6211, 6217, 6221, 6229, 6247, 6257, 6263,
6269, 6271, 6277, 6287, 6299, 6301, 6311, 6317, 6323, 6329, 6337,
6343, 6353, 6359, 6361, 6367, 6373, 6379, 6389, 6397, 6421, 6427,
6449, 6451, 6469, 6473, 6481, 6491, 6521, 6529, 6547, 6551, 6553,
6563, 6569, 6571, 6577, 6581, 6599, 6607, 6619, 6637, 6653, 6659,
6661, 6673, 6679, 6689, 6691, 6701, 6703, 6709, 6719, 6733, 6737,
6761, 6763, 6779, 6781, 6791, 6793, 6803, 6823, 6827, 6829, 6833,
6841, 6857, 6863, 6869, 6871, 6883, 6899, 6907, 6911, 6917, 6947,
6949, 6959, 6961, 6967, 6971, 6977, 6983, 6991, 6997, 7001, 7013,
7019, 7027, 7039, 7043, 7057, 7069, 7079, 7103, 7109, 7121, 7127,
7129, 7151, 7159, 7177, 7187, 7193, 7207, 7211, 7213, 7219, 7229,
7237, 7243, 7247, 7253, 7283, 7297, 7307, 7309, 7321, 7331, 7333,
7349, 7351, 7369, 7393, 7411, 7417, 7433, 7451, 7457, 7459, 7477,
7481, 7487, 7489, 7499, 7507, 7517, 7523, 7529, 7537, 7541, 7547,
7549, 7559, 7561, 7573, 7577, 7583, 7589, 7591, 7603, 7607, 7621,
7639, 7643, 7649, 7669, 7673, 7681, 7687, 7691, 7699, 7703, 7717,
7723, 7727, 7741, 7753, 7757, 7759, 7789, 7793, 7817, 7823, 7829,
7841, 7853, 7867, 7873, 7877, 7879, 7883, 7901, 7907, 7919, 7927,
7933, 7937, 7949, 7951, 7963, 7993, 8009, 8011, 8017, 8039, 8053,
8059, 8069, 8081, 8087, 8089, 8093, 8101, 8111, 8117, 8123, 8147,
8161, 8167, 8171, 8179, 8191, 8209, 8219, 8221, 8231, 8233, 8237,
8243, 8263, 8269, 8273, 8287, 8291, 8293, 8297, 8311, 8317, 8329,
8353, 8363, 8369, 8377, 8387, 8389, 8419, 8423, 8429, 8431, 8443,
8447, 8461, 8467, 8501, 8513, 8521, 8527, 8537, 8539, 8543, 8563,
8573, 8581, 8597, 8599, 8609, 8623, 8627, 8629, 8641, 8647, 8663,
8669, 8677, 8681, 8689, 8693, 8699, 8707, 8713, 8719, 8731, 8737,
8741, 8747, 8753, 8761, 8779, 8783, 8803, 8807, 8819, 8821, 8831,
8837, 8839, 8849, 8861, 8863, 8867, 8887, 8893, 8923, 8929, 8933,
8941, 8951, 8963, 8969, 8971, 8999, 9001, 9007, 9011, 9013, 9029,
9041, 9043, 9049, 9059, 9067, 9091, 9103, 9109, 9127, 9133, 9137,
9151, 9157, 9161, 9173, 9181, 9187, 9199, 9203, 9209, 9221, 9227,
9239, 9241, 9257, 9277, 9281, 9283, 9293, 9311, 9319, 9323, 9337,
9341, 9343, 9349, 9371, 9377, 9391, 9397, 9403, 9413, 9419, 9421,
9431, 9433, 9437, 9439, 9461, 9463, 9467, 9473, 9479, 9491, 9497,
9511, 9521, 9533, 9539, 9547, 9551, 9587, 9601, 9613, 9619, 9623,
9629, 9631, 9643, 9649, 9661, 9677, 9679, 9689, 9697, 9719, 9721,
9733, 9739, 9743, 9749, 9767, 9769, 9781, 9787, 9791, 9803, 9811,
9817, 9829, 9833, 9839, 9851, 9857, 9859, 9871, 9883, 9887, 9901,
9907, 9923, 9929, 9931, 9941, 9949, 9967, 9973, 10007, 10009, 10037,
10039, 10061, 10067, 10069, 10079, 10091, 10093, 10099, 10103, 10111, 10133,
10139, 10141, 10151, 10159, 10163, 10169, 10177, 10181, 10193, 10211, 10223,
10243, 10247, 10253, 10259, 10267, 10271, 10273, 10289, 10301, 10303, 10313,
10321, 10331, 10333, 10337, 10343, 10357, 10369, 10391, 10399, 10427, 10429,
10433, 10453, 10457, 10459, 10463, 10477, 10487, 10499, 10501, 10513, 10529,
10531, 10559, 10567, 10589, 10597, 10601, 10607, 10613, 10627, 10631, 10639,
10651, 10657, 10663, 10667, 10687, 10691, 10709, 10711, 10723, 10729, 10733,
10739, 10753, 10771, 10781, 10789, 10799, 10831, 10837, 10847, 10853, 10859,
10861, 10867, 10883, 10889, 10891, 10903, 10909, 10937, 10939, 10949, 10957,
10973, 10979, 10987, 10993, 11003, 11027, 11047, 11057, 11059, 11069, 11071,
11083, 11087, 11093, 11113, 11117, 11119, 11131, 11149, 11159, 11161, 11171,
11173, 11177, 11197, 11213, 11239, 11243, 11251, 11257, 11261, 11273, 11279,
11287, 11299, 11311, 11317, 11321, 11329, 11351, 11353, 11369, 11383, 11393,
11399, 11411, 11423, 11437, 11443, 11447, 11467, 11471, 11483, 11489, 11491,
11497, 11503, 11519, 11527, 11549, 11551, 11579, 11587, 11593, 11597, 11617,
11621, 11633, 11657, 11677, 11681, 11689, 11699, 11701, 11717, 11719, 11731,
11743, 11777, 11779, 11783, 11789, 11801, 11807, 11813, 11821, 11827, 11831,
11833, 11839, 11863, 11867, 11887, 11897, 11903, 11909, 11923, 11927, 11933,
11939, 11941, 11953, 11959, 11969, 11971, 11981, 11987, 12007, 12011, 12037,
12041, 12043, 12049, 12071, 12073, 12097, 12101, 12107, 12109, 12113, 12119,
12143, 12149, 12157, 12161, 12163, 12197, 12203, 12211, 12227, 12239, 12241,
12251, 12253, 12263, 12269, 12277, 12281, 12289, 12301, 12323, 12329, 12343,
12347, 12373, 12377, 12379, 12391, 12401, 12409, 12413, 12421, 12433, 12437,
12451, 12457, 12473, 12479, 12487, 12491, 12497, 12503, 12511, 12517, 12527,
12539, 12541, 12547, 12553, 12569, 12577, 12583, 12589, 12601, 12611, 12613,
12619, 12637, 12641, 12647, 12653, 12659, 12671, 12689, 12697, 12703, 12713,
12721, 12739, 12743, 12757, 12763, 12781, 12791, 12799, 12809, 12821, 12823,
12829, 12841, 12853, 12889, 12893, 12899, 12907, 12911, 12917, 12919, 12923,
12941, 12953, 12959, 12967, 12973, 12979, 12983, 13001, 13003, 13007, 13009,
13033, 13037, 13043, 13049, 13063, 13093, 13099, 13103, 13109, 13121, 13127,
13147, 13151, 13159, 13163, 13171, 13177, 13183, 13187, 13217, 13219, 13229,
13241, 13249, 13259, 13267, 13291, 13297, 13309, 13313, 13327, 13331, 13337,
13339, 13367, 13381, 13397, 13399, 13411, 13417, 13421, 13441, 13451, 13457,
13463, 13469, 13477, 13487, 13499, 13513, 13523, 13537, 13553, 13567, 13577,
13591, 13597, 13613, 13619, 13627, 13633, 13649, 13669, 13679, 13681, 13687,
13691, 13693, 13697, 13709, 13711, 13721, 13723, 13729, 13751, 13757, 13759,
13763, 13781, 13789, 13799, 13807, 13829, 13831, 13841, 13859, 13873, 13877,
13879, 13883, 13901, 13903, 13907, 13913, 13921, 13931, 13933, 13963, 13967,
13997, 13999, 14009, 14011, 14029, 14033, 14051, 14057, 14071, 14081, 14083,
14087, 14107, 14143, 14149, 14153, 14159, 14173, 14177, 14197, 14207, 14221,
14243, 14249, 14251, 14281, 14293, 14303, 14321, 14323, 14327, 14341, 14347,
14369, 14387, 14389, 14401, 14407, 14411, 14419, 14423, 14431, 14437, 14447,
14449, 14461, 14479, 14489, 14503, 14519, 14533, 14537, 14543, 14549, 14551,
14557, 14561, 14563, 14591, 14593, 14621, 14627, 14629, 14633, 14639, 14653,
14657, 14669, 14683, 14699, 14713, 14717, 14723, 14731, 14737, 14741, 14747,
14753, 14759, 14767, 14771, 14779, 14783, 14797, 14813, 14821, 14827, 14831,
14843, 14851, 14867, 14869, 14879, 14887, 14891, 14897, 14923, 14929, 14939,
14947, 14951, 14957, 14969, 14983, 15013, 15017, 15031, 15053, 15061, 15073,
15077, 15083, 15091, 15101, 15107, 15121, 15131, 15137, 15139, 15149, 15161,
15173, 15187, 15193, 15199, 15217, 15227, 15233, 15241, 15259, 15263, 15269,
15271, 15277, 15287, 15289, 15299, 15307, 15313, 15319, 15329, 15331, 15349,
15359, 15361, 15373, 15377, 15383, 15391, 15401, 15413, 15427, 15439, 15443,
15451, 15461, 15467, 15473, 15493, 15497, 15511, 15527, 15541, 15551, 15559,
15569, 15581, 15583, 15601, 15607, 15619, 15629, 15641, 15643, 15647, 15649,
15661, 15667, 15671, 15679, 15683, 15727, 15731, 15733, 15737, 15739, 15749,
15761, 15767, 15773, 15787, 15791, 15797, 15803, 15809, 15817, 15823, 15859,
15877, 15881, 15887, 15889, 15901, 15907, 15913, 15919, 15923, 15937, 15959,
15971, 15973, 15991, 16001, 16007, 16033, 16057, 16061, 16063, 16067, 16069,
16073, 16087, 16091, 16097, 16103, 16111, 16127, 16139, 16141, 16183, 16187,
16189, 16193, 16217, 16223, 16229, 16231, 16249, 16253, 16267, 16273, 16301,
16319, 16333, 16339, 16349, 16361, 16363, 16369, 16381, 16411, 16417, 16421,
16427, 16433, 16447, 16451, 16453, 16477, 16481, 16487, 16493, 16519, 16529,
16547, 16553, 16561, 16567, 16573, 16603, 16607, 16619, 16631, 16633, 16649,
16651, 16657, 16661, 16673, 16691, 16693, 16699, 16703, 16729, 16741, 16747,
16759, 16763, 16787, 16811, 16823, 16829, 16831, 16843, 16871, 16879, 16883,
16889, 16901, 16903, 16921, 16927, 16931, 16937, 16943, 16963, 16979, 16981,
16987, 16993, 17011, 17021, 17027, 17029, 17033, 17041, 17047, 17053, 17077,
17093, 17099, 17107, 17117, 17123, 17137, 17159, 17167, 17183, 17189, 17191,
17203, 17207, 17209, 17231, 17239, 17257, 17291, 17293, 17299, 17317, 17321,
17327, 17333, 17341, 17351, 17359, 17377, 17383, 17387, 17389, 17393, 17401,
17417, 17419, 17431, 17443, 17449, 17467, 17471, 17477, 17483, 17489, 17491,
17497, 17509, 17519, 17539, 17551, 17569, 17573, 17579, 17581, 17597, 17599,
17609, 17623, 17627, 17657, 17659, 17669, 17681, 17683, 17707, 17713, 17729,
17737, 17747, 17749, 17761, 17783, 17789, 17791, 17807, 17827, 17837, 17839,
17851, 17863,
};
// BN_prime_checks_for_size returns the number of Miller-Rabin iterations
// necessary for a 'bits'-bit prime, in order to maintain an error rate greater
// than the security level for an RSA prime of that many bits (calculated using
// the FIPS SP 800-57 security level and 186-4 Section F.1; original paper:
// Damgaard, Landrock, Pomerance: Average case error estimates for the strong
// probable prime test. -- Math. Comp. 61 (1993) 177-194)
static int BN_prime_checks_for_size(int bits) {
if (bits >= 3747) {
return 3;
}
if (bits >= 1345) {
return 4;
}
if (bits >= 476) {
return 5;
}
if (bits >= 400) {
return 6;
}
if (bits >= 308) {
return 8;
}
if (bits >= 205) {
return 13;
}
if (bits >= 155) {
return 19;
}
return 28;
}
// BN_PRIME_CHECKS_BLINDED is the iteration count for blinding the constant-time
// primality test. See |BN_primality_test| for details. This number is selected
// so that, for a candidate N-bit RSA prime, picking |BN_PRIME_CHECKS_BLINDED|
// random N-bit numbers will have at least |BN_prime_checks_for_size(N)| values
// in range with high probability.
//
// The following Python script computes the blinding factor needed for the
// corresponding iteration count.
/*
import math
# We choose candidate RSA primes between sqrt(2)/2 * 2^N and 2^N and select
# witnesses by generating random N-bit numbers. Thus the probability of
# selecting one in range is at least sqrt(2)/2.
p = math.sqrt(2) / 2
# Target a 2^-80 probability of the blinding being insufficient.
epsilon = 2**-80
def choose(a, b):
r = 1
for i in xrange(b):
r *= a - i
r /= (i + 1)
return r
def failure_rate(min_uniform, iterations):
""" Returns the probability that, for |iterations| candidate witnesses, fewer
than |min_uniform| of them will be uniform. """
prob = 0.0
for i in xrange(min_uniform):
prob += (choose(iterations, i) *
p**i * (1-p)**(iterations - i))
return prob
for min_uniform in (3, 4, 5, 6, 8, 13, 19, 28):
# Find the smallest number of iterations under the target failure rate.
iterations = min_uniform
while True:
prob = failure_rate(min_uniform, iterations)
if prob < epsilon:
print min_uniform, iterations, prob
break
iterations += 1
Output:
3 53 4.43927387758e-25
4 56 5.4559565573e-25
5 59 5.47044804496e-25
6 62 4.74781795233e-25
8 67 8.11486028886e-25
13 80 5.52341867763e-25
19 94 5.74309668718e-25
28 114 4.39583733951e-25
64 iterations suffices for 400-bit primes and larger (6 uniform samples needed),
which is already well below the minimum acceptable key size for RSA.
*/
#define BN_PRIME_CHECKS_BLINDED 64
static int probable_prime(BIGNUM *rnd, int bits);
static int probable_prime_dh(BIGNUM *rnd, int bits, const BIGNUM *add,
const BIGNUM *rem, BN_CTX *ctx);
static int probable_prime_dh_safe(BIGNUM *rnd, int bits, const BIGNUM *add,
const BIGNUM *rem, BN_CTX *ctx);
void BN_GENCB_set(BN_GENCB *callback,
int (*f)(int event, int n, struct bn_gencb_st *),
void *arg) {
callback->callback = f;
callback->arg = arg;
}
int BN_GENCB_call(BN_GENCB *callback, int event, int n) {
if (!callback) {
return 1;
}
return callback->callback(event, n, callback);
}
int BN_generate_prime_ex(BIGNUM *ret, int bits, int safe, const BIGNUM *add,
const BIGNUM *rem, BN_GENCB *cb) {
BIGNUM *t;
int found = 0;
int i, j, c1 = 0;
BN_CTX *ctx;
int checks = BN_prime_checks_for_size(bits);
if (bits < 2) {
// There are no prime numbers this small.
OPENSSL_PUT_ERROR(BN, BN_R_BITS_TOO_SMALL);
return 0;
} else if (bits == 2 && safe) {
// The smallest safe prime (7) is three bits.
OPENSSL_PUT_ERROR(BN, BN_R_BITS_TOO_SMALL);
return 0;
}
ctx = BN_CTX_new();
if (ctx == NULL) {
goto err;
}
BN_CTX_start(ctx);
t = BN_CTX_get(ctx);
if (!t) {
goto err;
}
loop:
// make a random number and set the top and bottom bits
if (add == NULL) {
if (!probable_prime(ret, bits)) {
goto err;
}
} else {
if (safe) {
if (!probable_prime_dh_safe(ret, bits, add, rem, ctx)) {
goto err;
}
} else {
if (!probable_prime_dh(ret, bits, add, rem, ctx)) {
goto err;
}
}
}
if (!BN_GENCB_call(cb, BN_GENCB_GENERATED, c1++)) {
// aborted
goto err;
}
if (!safe) {
i = BN_is_prime_fasttest_ex(ret, checks, ctx, 0, cb);
if (i == -1) {
goto err;
} else if (i == 0) {
goto loop;
}
} else {
// for "safe prime" generation, check that (p-1)/2 is prime. Since a prime
// is odd, We just need to divide by 2
if (!BN_rshift1(t, ret)) {
goto err;
}
for (i = 0; i < checks; i++) {
j = BN_is_prime_fasttest_ex(ret, 1, ctx, 0, NULL);
if (j == -1) {
goto err;
} else if (j == 0) {
goto loop;
}
j = BN_is_prime_fasttest_ex(t, 1, ctx, 0, NULL);
if (j == -1) {
goto err;
} else if (j == 0) {
goto loop;
}
if (!BN_GENCB_call(cb, i, c1 - 1)) {
goto err;
}
// We have a safe prime test pass
}
}
// we have a prime :-)
found = 1;
err:
if (ctx != NULL) {
BN_CTX_end(ctx);
BN_CTX_free(ctx);
}
return found;
}
// The following functions use a Barrett reduction variant to avoid leaking the
// numerator. See http://ridiculousfish.com/blog/posts/labor-of-division-episode-i.html
//
// We use 32-bit numerator and 16-bit divisor for simplicity. This allows
// computing |m| and |q| without architecture-specific code.
// mod_u16 returns |n| mod |d|. |p| and |m| are the "magic numbers" for |d| (see
// reference). For proof of correctness in Coq, see
// https://github.com/davidben/fiat-crypto/blob/barrett/src/Arithmetic/BarrettReduction/RidiculousFish.v
// Note the Coq version of |mod_u16| additionally includes the computation of
// |p| and |m| from |bn_mod_u16_consttime| below.
static uint16_t mod_u16(uint32_t n, uint16_t d, uint32_t p, uint32_t m) {
// Compute floor(n/d) per steps 3 through 5.
uint32_t q = ((uint64_t)m * n) >> 32;
// Note there is a typo in the reference. We right-shift by one, not two.
uint32_t t = ((n - q) >> 1) + q;
t = t >> (p - 1);
// Multiply and subtract to get the remainder.
n -= d * t;
assert(n < d);
return n;
}
// shift_and_add_mod_u16 returns |r| * 2^32 + |a| mod |d|. |p| and |m| are the
// "magic numbers" for |d| (see reference).
static uint16_t shift_and_add_mod_u16(uint16_t r, uint32_t a, uint16_t d,
uint32_t p, uint32_t m) {
// Incorporate |a| in two 16-bit chunks.
uint32_t t = r;
t <<= 16;
t |= a >> 16;
t = mod_u16(t, d, p, m);
t <<= 16;
t |= a & 0xffff;
t = mod_u16(t, d, p, m);
return t;
}
uint16_t bn_mod_u16_consttime(const BIGNUM *bn, uint16_t d) {
if (d <= 1) {
return 0;
}
// Compute the "magic numbers" for |d|. See steps 1 and 2.
// This computes p = ceil(log_2(d)).
uint32_t p = BN_num_bits_word(d - 1);
// This operation is not constant-time, but |p| and |d| are public values.
// Note that |p| is at most 16, so the computation fits in |uint64_t|.
assert(p <= 16);
uint32_t m = ((UINT64_C(1) << (32 + p)) + d - 1) / d;
uint16_t ret = 0;
for (int i = bn->width - 1; i >= 0; i--) {
#if BN_BITS2 == 32
ret = shift_and_add_mod_u16(ret, bn->d[i], d, p, m);
#elif BN_BITS2 == 64
ret = shift_and_add_mod_u16(ret, bn->d[i] >> 32, d, p, m);
ret = shift_and_add_mod_u16(ret, bn->d[i] & 0xffffffff, d, p, m);
#else
#error "Unknown BN_ULONG size"
#endif
}
return ret;
}
static int bn_trial_division(uint16_t *out, const BIGNUM *bn) {
for (int i = 1; i < NUMPRIMES; i++) {
if (bn_mod_u16_consttime(bn, primes[i]) == 0) {
*out = primes[i];
return 1;
}
}
return 0;
}
int bn_odd_number_is_obviously_composite(const BIGNUM *bn) {
uint16_t prime;
return bn_trial_division(&prime, bn) && !BN_is_word(bn, prime);
}
int BN_primality_test(int *is_probably_prime, const BIGNUM *w,
int iterations, BN_CTX *ctx, int do_trial_division,
BN_GENCB *cb) {
*is_probably_prime = 0;
// To support RSA key generation, this function should treat |w| as secret if
// it is a large prime. Composite numbers are discarded, so they may return
// early.
if (BN_cmp(w, BN_value_one()) <= 0) {
return 1;
}
if (!BN_is_odd(w)) {
// The only even prime is two.
*is_probably_prime = BN_is_word(w, 2);
return 1;
}
// Miller-Rabin does not work for three.
if (BN_is_word(w, 3)) {
*is_probably_prime = 1;
return 1;
}
if (do_trial_division) {
// Perform additional trial division checks to discard small primes.
uint16_t prime;
if (bn_trial_division(&prime, w)) {
*is_probably_prime = BN_is_word(w, prime);
return 1;
}
if (!BN_GENCB_call(cb, 1, -1)) {
return 0;
}
}
if (iterations == BN_prime_checks) {
iterations = BN_prime_checks_for_size(BN_num_bits(w));
}
// See C.3.1 from FIPS 186-4.
int ret = 0;
BN_MONT_CTX *mont = NULL;
BN_CTX_start(ctx);
BIGNUM *w1 = BN_CTX_get(ctx);
if (w1 == NULL ||
!bn_usub_consttime(w1, w, BN_value_one())) {
goto err;
}
// Write w1 as m * 2^a (Steps 1 and 2).
int w_len = BN_num_bits(w);
int a = BN_count_low_zero_bits(w1);
BIGNUM *m = BN_CTX_get(ctx);
if (m == NULL ||
!bn_rshift_secret_shift(m, w1, a, ctx)) {
goto err;
}
// Montgomery setup for computations mod w. Additionally, compute 1 and w - 1
// in the Montgomery domain for later comparisons.
BIGNUM *b = BN_CTX_get(ctx);
BIGNUM *z = BN_CTX_get(ctx);
BIGNUM *one_mont = BN_CTX_get(ctx);
BIGNUM *w1_mont = BN_CTX_get(ctx);
mont = BN_MONT_CTX_new_for_modulus(w, ctx);
if (b == NULL || z == NULL || one_mont == NULL || w1_mont == NULL ||
mont == NULL ||
!bn_one_to_montgomery(one_mont, mont, ctx) ||
// w - 1 is -1 mod w, so we can compute it in the Montgomery domain, -R,
// with a subtraction. (|one_mont| cannot be zero.)
!bn_usub_consttime(w1_mont, w, one_mont)) {
goto err;
}
// The following loop performs in inner iteration of the Miller-Rabin
// Primality test (Step 4).
//
// The algorithm as specified in FIPS 186-4 leaks information on |w|, the RSA
// private key. Instead, we run through each iteration unconditionally,
// performing modular multiplications, masking off any effects to behave
// equivalently to the specified algorithm.
//
// We also blind the number of values of |b| we try. Steps 4.1–4.2 say to
// discard out-of-range values. To avoid leaking information on |w|, we use
// |bn_rand_secret_range| which, rather than discarding bad values, adjusts
// them to be in range. Though not uniformly selected, these adjusted values
// are still usable as Rabin-Miller checks.
//
// Rabin-Miller is already probabilistic, so we could reach the desired
// confidence levels by just suitably increasing the iteration count. However,
// to align with FIPS 186-4, we use a more pessimal analysis: we do not count
// the non-uniform values towards the iteration count. As a result, this
// function is more complex and has more timing risk than necessary.
//
// We count both total iterations and uniform ones and iterate until we've
// reached at least |BN_PRIME_CHECKS_BLINDED| and |iterations|, respectively.
// If the latter is large enough, it will be the limiting factor with high
// probability and we won't leak information.
//
// Note this blinding does not impact most calls when picking primes because
// composites are rejected early. Only the two secret primes see extra work.
crypto_word_t uniform_iterations = 0;
// Using |constant_time_lt_w| seems to prevent the compiler from optimizing
// this into two jumps.
for (int i = 1; (i <= BN_PRIME_CHECKS_BLINDED) |
constant_time_lt_w(uniform_iterations, iterations);
i++) {
int is_uniform;
if (// Step 4.1-4.2
!bn_rand_secret_range(b, &is_uniform, 2, w1) ||
// Step 4.3
!BN_mod_exp_mont_consttime(z, b, m, w, ctx, mont)) {
goto err;
}
uniform_iterations += is_uniform;
// loop_done is all ones if the loop has completed and all zeros otherwise.
crypto_word_t loop_done = 0;
// next_iteration is all ones if we should continue to the next iteration
// (|b| is not a composite witness for |w|). This is equivalent to going to
// step 4.7 in the original algorithm.
crypto_word_t next_iteration = 0;
// Step 4.4. If z = 1 or z = w-1, mask off the loop and continue to the next
// iteration (go to step 4.7).
loop_done = BN_equal_consttime(z, BN_value_one()) |
BN_equal_consttime(z, w1);
loop_done = 0 - loop_done; // Make it all zeros or all ones.
next_iteration = loop_done; // Go to step 4.7 if |loop_done|.
// Step 4.5. We use Montgomery-encoding for better performance and to avoid
// timing leaks.
if (!BN_to_montgomery(z, z, mont, ctx)) {
goto err;
}
// To avoid leaking |a|, we run the loop to |w_len| and mask off all
// iterations once |j| = |a|.
for (int j = 1; j < w_len; j++) {
loop_done |= constant_time_eq_int(j, a);
// Step 4.5.1.
if (!BN_mod_mul_montgomery(z, z, z, mont, ctx)) {
goto err;
}
// Step 4.5.2. If z = w-1 and the loop is not done, run through the next
// iteration.
crypto_word_t z_is_w1_mont = BN_equal_consttime(z, w1_mont) & ~loop_done;
z_is_w1_mont = 0 - z_is_w1_mont; // Make it all zeros or all ones.
loop_done |= z_is_w1_mont;
next_iteration |= z_is_w1_mont; // Go to step 4.7 if |z_is_w1_mont|.
// Step 4.5.3. If z = 1 and the loop is not done, w is composite and we
// may exit in variable time.
if (BN_equal_consttime(z, one_mont) & ~loop_done) {
assert(!next_iteration);
break;
}
}
if (!next_iteration) {
// Step 4.6. We did not see z = w-1 before z = 1, so w must be composite.
// (For any prime, the value of z immediately preceding 1 must be -1.
// There are no non-trivial square roots of 1 modulo a prime.)
*is_probably_prime = 0;
ret = 1;
goto err;
}
// Step 4.7
if (!BN_GENCB_call(cb, 1, i)) {
goto err;
}
}
assert(uniform_iterations >= (crypto_word_t)iterations);
*is_probably_prime = 1;
ret = 1;
err:
BN_MONT_CTX_free(mont);
BN_CTX_end(ctx);
return ret;
}
int BN_is_prime_ex(const BIGNUM *candidate, int checks, BN_CTX *ctx, BN_GENCB *cb) {
return BN_is_prime_fasttest_ex(candidate, checks, ctx, 0, cb);
}
int BN_is_prime_fasttest_ex(const BIGNUM *a, int checks, BN_CTX *ctx,
int do_trial_division, BN_GENCB *cb) {
int is_probably_prime;
if (!BN_primality_test(&is_probably_prime, a, checks, ctx, do_trial_division,
cb)) {
return -1;
}
return is_probably_prime;
}
int BN_enhanced_miller_rabin_primality_test(
enum bn_primality_result_t *out_result, const BIGNUM *w, int iterations,
BN_CTX *ctx, BN_GENCB *cb) {
// Enhanced Miller-Rabin is only valid on odd integers greater than 3.
if (!BN_is_odd(w) || BN_cmp_word(w, 3) <= 0) {
OPENSSL_PUT_ERROR(BN, BN_R_INVALID_INPUT);
return 0;
}
if (iterations == BN_prime_checks) {
iterations = BN_prime_checks_for_size(BN_num_bits(w));
}
int ret = 0;
BN_MONT_CTX *mont = NULL;
BN_CTX_start(ctx);
BIGNUM *w1 = BN_CTX_get(ctx);
if (w1 == NULL ||
!BN_copy(w1, w) ||
!BN_sub_word(w1, 1)) {
goto err;
}
// Write w1 as m*2^a (Steps 1 and 2).
int a = 0;
while (!BN_is_bit_set(w1, a)) {
a++;
}
BIGNUM *m = BN_CTX_get(ctx);
if (m == NULL ||
!BN_rshift(m, w1, a)) {
goto err;
}
BIGNUM *b = BN_CTX_get(ctx);
BIGNUM *g = BN_CTX_get(ctx);
BIGNUM *z = BN_CTX_get(ctx);
BIGNUM *x = BN_CTX_get(ctx);
BIGNUM *x1 = BN_CTX_get(ctx);
if (b == NULL ||
g == NULL ||
z == NULL ||
x == NULL ||
x1 == NULL) {
goto err;
}
// Montgomery setup for computations mod w
mont = BN_MONT_CTX_new_for_modulus(w, ctx);
if (mont == NULL) {
goto err;
}
// The following loop performs in inner iteration of the Enhanced Miller-Rabin
// Primality test (Step 4).
for (int i = 1; i <= iterations; i++) {
// Step 4.1-4.2
if (!BN_rand_range_ex(b, 2, w1)) {
goto err;
}
// Step 4.3-4.4
if (!BN_gcd(g, b, w, ctx)) {
goto err;
}
if (BN_cmp_word(g, 1) > 0) {
*out_result = bn_composite;
ret = 1;
goto err;
}
// Step 4.5
if (!BN_mod_exp_mont(z, b, m, w, ctx, mont)) {
goto err;
}
// Step 4.6
if (BN_is_one(z) || BN_cmp(z, w1) == 0) {
goto loop;
}
// Step 4.7
for (int j = 1; j < a; j++) {
if (!BN_copy(x, z) || !BN_mod_mul(z, x, x, w, ctx)) {
goto err;
}
if (BN_cmp(z, w1) == 0) {
goto loop;
}
if (BN_is_one(z)) {
goto composite;
}
}
// Step 4.8-4.9
if (!BN_copy(x, z) || !BN_mod_mul(z, x, x, w, ctx)) {
goto err;
}
// Step 4.10-4.11
if (!BN_is_one(z) && !BN_copy(x, z)) {
goto err;
}
composite:
// Step 4.12-4.14
if (!BN_copy(x1, x) ||
!BN_sub_word(x1, 1) ||
!BN_gcd(g, x1, w, ctx)) {
goto err;
}
if (BN_cmp_word(g, 1) > 0) {
*out_result = bn_composite;
} else {
*out_result = bn_non_prime_power_composite;
}
ret = 1;
goto err;
loop:
// Step 4.15
if (!BN_GENCB_call(cb, 1, i)) {
goto err;
}
}
*out_result = bn_probably_prime;
ret = 1;
err:
BN_MONT_CTX_free(mont);
BN_CTX_end(ctx);
return ret;
}
static int probable_prime(BIGNUM *rnd, int bits) {
int i;
uint16_t mods[NUMPRIMES];
BN_ULONG delta;
BN_ULONG maxdelta = BN_MASK2 - primes[NUMPRIMES - 1];
char is_single_word = bits <= BN_BITS2;
again:
if (!BN_rand(rnd, bits, BN_RAND_TOP_TWO, BN_RAND_BOTTOM_ODD)) {
return 0;
}
// we now have a random number 'rnd' to test.
for (i = 1; i < NUMPRIMES; i++) {
mods[i] = bn_mod_u16_consttime(rnd, primes[i]);
}
// If bits is so small that it fits into a single word then we
// additionally don't want to exceed that many bits.
if (is_single_word) {
BN_ULONG size_limit;
if (bits == BN_BITS2) {
// Avoid undefined behavior.
size_limit = ~((BN_ULONG)0) - BN_get_word(rnd);
} else {
size_limit = (((BN_ULONG)1) << bits) - BN_get_word(rnd) - 1;
}
if (size_limit < maxdelta) {
maxdelta = size_limit;
}
}
delta = 0;
loop:
if (is_single_word) {
BN_ULONG rnd_word = BN_get_word(rnd);
// In the case that the candidate prime is a single word then
// we check that:
// 1) It's greater than primes[i] because we shouldn't reject
// 3 as being a prime number because it's a multiple of
// three.
// 2) That it's not a multiple of a known prime. We don't
// check that rnd-1 is also coprime to all the known
// primes because there aren't many small primes where
// that's true.
for (i = 1; i < NUMPRIMES && primes[i] < rnd_word; i++) {
if ((mods[i] + delta) % primes[i] == 0) {
delta += 2;
if (delta > maxdelta) {
goto again;
}
goto loop;
}
}
} else {
for (i = 1; i < NUMPRIMES; i++) {
// check that rnd is not a prime and also
// that gcd(rnd-1,primes) == 1 (except for 2)
if (((mods[i] + delta) % primes[i]) <= 1) {
delta += 2;
if (delta > maxdelta) {
goto again;
}
goto loop;
}
}
}
if (!BN_add_word(rnd, delta)) {
return 0;
}
if (BN_num_bits(rnd) != (unsigned)bits) {
goto again;
}
return 1;
}
static int probable_prime_dh(BIGNUM *rnd, int bits, const BIGNUM *add,
const BIGNUM *rem, BN_CTX *ctx) {
int i, ret = 0;
BIGNUM *t1;
BN_CTX_start(ctx);
if ((t1 = BN_CTX_get(ctx)) == NULL) {
goto err;
}
if (!BN_rand(rnd, bits, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD)) {
goto err;
}
// we need ((rnd-rem) % add) == 0
if (!BN_mod(t1, rnd, add, ctx)) {
goto err;
}
if (!BN_sub(rnd, rnd, t1)) {
goto err;
}
if (rem == NULL) {
if (!BN_add_word(rnd, 1)) {
goto err;
}
} else {
if (!BN_add(rnd, rnd, rem)) {
goto err;
}
}
// we now have a random number 'rand' to test.
loop:
for (i = 1; i < NUMPRIMES; i++) {
// check that rnd is a prime
if (bn_mod_u16_consttime(rnd, primes[i]) <= 1) {
if (!BN_add(rnd, rnd, add)) {
goto err;
}
goto loop;
}
}
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}
static int probable_prime_dh_safe(BIGNUM *p, int bits, const BIGNUM *padd,
const BIGNUM *rem, BN_CTX *ctx) {
int i, ret = 0;
BIGNUM *t1, *qadd, *q;
bits--;
BN_CTX_start(ctx);
t1 = BN_CTX_get(ctx);
q = BN_CTX_get(ctx);
qadd = BN_CTX_get(ctx);
if (qadd == NULL) {
goto err;
}
if (!BN_rshift1(qadd, padd)) {
goto err;
}
if (!BN_rand(q, bits, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD)) {
goto err;
}
// we need ((rnd-rem) % add) == 0
if (!BN_mod(t1, q, qadd, ctx)) {
goto err;
}
if (!BN_sub(q, q, t1)) {
goto err;
}
if (rem == NULL) {
if (!BN_add_word(q, 1)) {
goto err;
}
} else {
if (!BN_rshift1(t1, rem)) {
goto err;
}
if (!BN_add(q, q, t1)) {
goto err;
}
}
// we now have a random number 'rand' to test.
if (!BN_lshift1(p, q)) {
goto err;
}
if (!BN_add_word(p, 1)) {
goto err;
}
loop:
for (i = 1; i < NUMPRIMES; i++) {
// check that p and q are prime
// check that for p and q
// gcd(p-1,primes) == 1 (except for 2)
if (bn_mod_u16_consttime(p, primes[i]) == 0 ||
bn_mod_u16_consttime(q, primes[i]) == 0) {
if (!BN_add(p, p, padd)) {
goto err;
}
if (!BN_add(q, q, qadd)) {
goto err;
}
goto loop;
}
}
ret = 1;
err:
BN_CTX_end(ctx);
return ret;
}
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