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Commit | Line | Data |
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4f22f405 | 1 | /* |
8240d5fa | 2 | * Copyright 1995-2019 The OpenSSL Project Authors. All Rights Reserved. |
4f22f405 | 3 | * |
367ace68 | 4 | * Licensed under the Apache License 2.0 (the "License"). You may not use |
4f22f405 RS |
5 | * this file except in compliance with the License. You can obtain a copy |
6 | * in the file LICENSE in the source distribution or at | |
7 | * https://www.openssl.org/source/license.html | |
bfe30e4d | 8 | */ |
d02b48c6 RE |
9 | |
10 | #include <stdio.h> | |
11 | #include <time.h> | |
b39fc560 | 12 | #include "internal/cryptlib.h" |
d02b48c6 | 13 | #include "bn_lcl.h" |
d02b48c6 | 14 | |
0f113f3e MC |
15 | /* |
16 | * The quick sieve algorithm approach to weeding out primes is Philip | |
17 | * Zimmermann's, as implemented in PGP. I have had a read of his comments | |
18 | * and implemented my own version. | |
d02b48c6 RE |
19 | */ |
20 | #include "bn_prime.h" | |
21 | ||
2934be91 | 22 | static int probable_prime(BIGNUM *rnd, int bits, prime_t *mods, BN_CTX *ctx); |
76aa0ddc | 23 | static int probable_prime_dh_safe(BIGNUM *rnd, int bits, |
0f113f3e MC |
24 | const BIGNUM *add, const BIGNUM *rem, |
25 | BN_CTX *ctx); | |
eb952088 | 26 | |
8240d5fa SL |
27 | #if BN_BITS2 == 64 |
28 | # define BN_DEF(lo, hi) (BN_ULONG)hi<<32|lo | |
29 | #else | |
30 | # define BN_DEF(lo, hi) lo, hi | |
31 | #endif | |
32 | ||
33 | /* | |
34 | * See SP800 89 5.3.3 (Step f) | |
35 | * The product of the set of primes ranging from 3 to 751 | |
36 | * Generated using process in test/bn_internal_test.c test_bn_small_factors(). | |
37 | * This includes 751 (which is not currently included in SP 800-89). | |
38 | */ | |
39 | static const BN_ULONG small_prime_factors[] = { | |
40 | BN_DEF(0x3ef4e3e1, 0xc4309333), BN_DEF(0xcd2d655f, 0x71161eb6), | |
41 | BN_DEF(0x0bf94862, 0x95e2238c), BN_DEF(0x24f7912b, 0x3eb233d3), | |
42 | BN_DEF(0xbf26c483, 0x6b55514b), BN_DEF(0x5a144871, 0x0a84d817), | |
43 | BN_DEF(0x9b82210a, 0x77d12fee), BN_DEF(0x97f050b3, 0xdb5b93c2), | |
44 | BN_DEF(0x4d6c026b, 0x4acad6b9), BN_DEF(0x54aec893, 0xeb7751f3), | |
45 | BN_DEF(0x36bc85c4, 0xdba53368), BN_DEF(0x7f5ec78e, 0xd85a1b28), | |
46 | BN_DEF(0x6b322244, 0x2eb072d8), BN_DEF(0x5e2b3aea, 0xbba51112), | |
47 | BN_DEF(0x0e2486bf, 0x36ed1a6c), BN_DEF(0xec0c5727, 0x5f270460), | |
48 | (BN_ULONG)0x000017b1 | |
49 | }; | |
50 | ||
51 | #define BN_SMALL_PRIME_FACTORS_TOP OSSL_NELEM(small_prime_factors) | |
52 | static const BIGNUM _bignum_small_prime_factors = { | |
53 | (BN_ULONG *)small_prime_factors, | |
54 | BN_SMALL_PRIME_FACTORS_TOP, | |
55 | BN_SMALL_PRIME_FACTORS_TOP, | |
56 | 0, | |
57 | BN_FLG_STATIC_DATA | |
58 | }; | |
59 | ||
60 | const BIGNUM *bn_get0_small_factors(void) | |
61 | { | |
62 | return &_bignum_small_prime_factors; | |
63 | } | |
64 | ||
e9224c71 | 65 | int BN_GENCB_call(BN_GENCB *cb, int a, int b) |
0f113f3e MC |
66 | { |
67 | /* No callback means continue */ | |
68 | if (!cb) | |
69 | return 1; | |
70 | switch (cb->ver) { | |
71 | case 1: | |
72 | /* Deprecated-style callbacks */ | |
73 | if (!cb->cb.cb_1) | |
74 | return 1; | |
75 | cb->cb.cb_1(a, b, cb->arg); | |
76 | return 1; | |
77 | case 2: | |
78 | /* New-style callbacks */ | |
79 | return cb->cb.cb_2(a, b, cb); | |
80 | default: | |
81 | break; | |
82 | } | |
83 | /* Unrecognised callback type */ | |
84 | return 0; | |
85 | } | |
e9224c71 | 86 | |
2934be91 MC |
87 | int BN_generate_prime_ex2(BIGNUM *ret, int bits, int safe, |
88 | const BIGNUM *add, const BIGNUM *rem, BN_GENCB *cb, | |
89 | BN_CTX *ctx) | |
0f113f3e MC |
90 | { |
91 | BIGNUM *t; | |
92 | int found = 0; | |
93 | int i, j, c1 = 0; | |
8e704858 | 94 | prime_t *mods = NULL; |
0f113f3e MC |
95 | int checks = BN_prime_checks_for_size(bits); |
96 | ||
97 | if (bits < 2) { | |
98 | /* There are no prime numbers this small. */ | |
2934be91 | 99 | BNerr(BN_F_BN_GENERATE_PRIME_EX2, BN_R_BITS_TOO_SMALL); |
0f113f3e | 100 | return 0; |
291f616c BE |
101 | } else if (add == NULL && safe && bits < 6 && bits != 3) { |
102 | /* | |
103 | * The smallest safe prime (7) is three bits. | |
104 | * But the following two safe primes with less than 6 bits (11, 23) | |
105 | * are unreachable for BN_rand with BN_RAND_TOP_TWO. | |
106 | */ | |
2934be91 | 107 | BNerr(BN_F_BN_GENERATE_PRIME_EX2, BN_R_BITS_TOO_SMALL); |
0f113f3e MC |
108 | return 0; |
109 | } | |
110 | ||
d71eb667 MC |
111 | mods = OPENSSL_zalloc(sizeof(*mods) * NUMPRIMES); |
112 | if (mods == NULL) | |
113 | goto err; | |
114 | ||
0f113f3e MC |
115 | BN_CTX_start(ctx); |
116 | t = BN_CTX_get(ctx); | |
e8e55976 | 117 | if (t == NULL) |
0f113f3e MC |
118 | goto err; |
119 | loop: | |
120 | /* make a random number and set the top and bottom bits */ | |
121 | if (add == NULL) { | |
2934be91 | 122 | if (!probable_prime(ret, bits, mods, ctx)) |
0f113f3e MC |
123 | goto err; |
124 | } else { | |
125 | if (safe) { | |
126 | if (!probable_prime_dh_safe(ret, bits, add, rem, ctx)) | |
127 | goto err; | |
128 | } else { | |
129 | if (!bn_probable_prime_dh(ret, bits, add, rem, ctx)) | |
130 | goto err; | |
131 | } | |
132 | } | |
d70a5627 | 133 | |
0f113f3e MC |
134 | if (!BN_GENCB_call(cb, 0, c1++)) |
135 | /* aborted */ | |
136 | goto err; | |
137 | ||
138 | if (!safe) { | |
139 | i = BN_is_prime_fasttest_ex(ret, checks, ctx, 0, cb); | |
140 | if (i == -1) | |
141 | goto err; | |
142 | if (i == 0) | |
143 | goto loop; | |
144 | } else { | |
145 | /* | |
146 | * for "safe prime" generation, check that (p-1)/2 is prime. Since a | |
147 | * prime is odd, We just need to divide by 2 | |
148 | */ | |
149 | if (!BN_rshift1(t, ret)) | |
150 | goto err; | |
151 | ||
152 | for (i = 0; i < checks; i++) { | |
153 | j = BN_is_prime_fasttest_ex(ret, 1, ctx, 0, cb); | |
154 | if (j == -1) | |
155 | goto err; | |
156 | if (j == 0) | |
157 | goto loop; | |
158 | ||
159 | j = BN_is_prime_fasttest_ex(t, 1, ctx, 0, cb); | |
160 | if (j == -1) | |
161 | goto err; | |
162 | if (j == 0) | |
163 | goto loop; | |
164 | ||
165 | if (!BN_GENCB_call(cb, 2, c1 - 1)) | |
166 | goto err; | |
167 | /* We have a safe prime test pass */ | |
168 | } | |
169 | } | |
170 | /* we have a prime :-) */ | |
171 | found = 1; | |
172 | err: | |
8e704858 | 173 | OPENSSL_free(mods); |
ce1415ed | 174 | BN_CTX_end(ctx); |
0f113f3e MC |
175 | bn_check_top(ret); |
176 | return found; | |
177 | } | |
178 | ||
2934be91 MC |
179 | #ifndef FIPS_MODE |
180 | int BN_generate_prime_ex(BIGNUM *ret, int bits, int safe, | |
181 | const BIGNUM *add, const BIGNUM *rem, BN_GENCB *cb) | |
182 | { | |
183 | BN_CTX *ctx = BN_CTX_new(); | |
184 | int retval; | |
185 | ||
186 | if (ctx == NULL) | |
187 | return 0; | |
188 | ||
189 | retval = BN_generate_prime_ex2(ret, bits, safe, add, rem, cb, ctx); | |
190 | ||
191 | BN_CTX_free(ctx); | |
192 | return retval; | |
193 | } | |
194 | #endif | |
195 | ||
0f113f3e MC |
196 | int BN_is_prime_ex(const BIGNUM *a, int checks, BN_CTX *ctx_passed, |
197 | BN_GENCB *cb) | |
198 | { | |
199 | return BN_is_prime_fasttest_ex(a, checks, ctx_passed, 0, cb); | |
200 | } | |
e74231ed | 201 | |
8240d5fa | 202 | /* See FIPS 186-4 C.3.1 Miller Rabin Probabilistic Primality Test. */ |
2934be91 | 203 | int BN_is_prime_fasttest_ex(const BIGNUM *w, int checks, BN_CTX *ctx, |
0f113f3e MC |
204 | int do_trial_division, BN_GENCB *cb) |
205 | { | |
8240d5fa | 206 | int i, status, ret = -1; |
2934be91 MC |
207 | #ifndef FIPS_MODE |
208 | BN_CTX *ctxlocal = NULL; | |
209 | #else | |
210 | ||
211 | if (ctx == NULL) | |
212 | return -1; | |
213 | #endif | |
7d79d13a | 214 | |
8240d5fa SL |
215 | /* w must be bigger than 1 */ |
216 | if (BN_cmp(w, BN_value_one()) <= 0) | |
0f113f3e MC |
217 | return 0; |
218 | ||
8240d5fa SL |
219 | /* w must be odd */ |
220 | if (BN_is_odd(w)) { | |
221 | /* Take care of the really small prime 3 */ | |
222 | if (BN_is_word(w, 3)) | |
223 | return 1; | |
224 | } else { | |
225 | /* 2 is the only even prime */ | |
226 | return BN_is_word(w, 2); | |
227 | } | |
0f113f3e MC |
228 | |
229 | /* first look for small factors */ | |
0f113f3e | 230 | if (do_trial_division) { |
d70a5627 | 231 | for (i = 1; i < NUMPRIMES; i++) { |
8240d5fa | 232 | BN_ULONG mod = BN_mod_word(w, primes[i]); |
d70a5627 | 233 | if (mod == (BN_ULONG)-1) |
8240d5fa | 234 | return -1; |
d70a5627 | 235 | if (mod == 0) |
8240d5fa | 236 | return BN_is_word(w, primes[i]); |
d70a5627 | 237 | } |
0f113f3e | 238 | if (!BN_GENCB_call(cb, 1, -1)) |
8240d5fa | 239 | return -1; |
0f113f3e | 240 | } |
2934be91 MC |
241 | #ifndef FIPS_MODE |
242 | if (ctx == NULL && (ctxlocal = ctx = BN_CTX_new()) == NULL) | |
0f113f3e | 243 | goto err; |
2934be91 | 244 | #endif |
0f113f3e | 245 | |
8240d5fa SL |
246 | ret = bn_miller_rabin_is_prime(w, checks, ctx, cb, 0, &status); |
247 | if (!ret) | |
0f113f3e | 248 | goto err; |
8240d5fa SL |
249 | ret = (status == BN_PRIMETEST_PROBABLY_PRIME); |
250 | err: | |
2934be91 MC |
251 | #ifndef FIPS_MODE |
252 | BN_CTX_free(ctxlocal); | |
253 | #endif | |
8240d5fa SL |
254 | return ret; |
255 | } | |
256 | ||
257 | /* | |
258 | * Refer to FIPS 186-4 C.3.2 Enhanced Miller-Rabin Probabilistic Primality Test. | |
259 | * OR C.3.1 Miller-Rabin Probabilistic Primality Test (if enhanced is zero). | |
260 | * The Step numbers listed in the code refer to the enhanced case. | |
261 | * | |
262 | * if enhanced is set, then status returns one of the following: | |
263 | * BN_PRIMETEST_PROBABLY_PRIME | |
264 | * BN_PRIMETEST_COMPOSITE_WITH_FACTOR | |
265 | * BN_PRIMETEST_COMPOSITE_NOT_POWER_OF_PRIME | |
266 | * if enhanced is zero, then status returns either | |
267 | * BN_PRIMETEST_PROBABLY_PRIME or | |
268 | * BN_PRIMETEST_COMPOSITE | |
269 | * | |
270 | * returns 0 if there was an error, otherwise it returns 1. | |
271 | */ | |
272 | int bn_miller_rabin_is_prime(const BIGNUM *w, int iterations, BN_CTX *ctx, | |
273 | BN_GENCB *cb, int enhanced, int *status) | |
274 | { | |
275 | int i, j, a, ret = 0; | |
276 | BIGNUM *g, *w1, *w3, *x, *m, *z, *b; | |
277 | BN_MONT_CTX *mont = NULL; | |
0f113f3e | 278 | |
8240d5fa SL |
279 | /* w must be odd */ |
280 | if (!BN_is_odd(w)) | |
281 | return 0; | |
282 | ||
283 | BN_CTX_start(ctx); | |
284 | g = BN_CTX_get(ctx); | |
285 | w1 = BN_CTX_get(ctx); | |
286 | w3 = BN_CTX_get(ctx); | |
287 | x = BN_CTX_get(ctx); | |
288 | m = BN_CTX_get(ctx); | |
289 | z = BN_CTX_get(ctx); | |
290 | b = BN_CTX_get(ctx); | |
291 | ||
292 | if (!(b != NULL | |
293 | /* w1 := w - 1 */ | |
294 | && BN_copy(w1, w) | |
295 | && BN_sub_word(w1, 1) | |
296 | /* w3 := w - 3 */ | |
297 | && BN_copy(w3, w) | |
298 | && BN_sub_word(w3, 3))) | |
0f113f3e | 299 | goto err; |
8240d5fa SL |
300 | |
301 | /* check w is larger than 3, otherwise the random b will be too small */ | |
302 | if (BN_is_zero(w3) || BN_is_negative(w3)) | |
0f113f3e | 303 | goto err; |
0f113f3e | 304 | |
8240d5fa SL |
305 | /* (Step 1) Calculate largest integer 'a' such that 2^a divides w-1 */ |
306 | a = 1; | |
307 | while (!BN_is_bit_set(w1, a)) | |
308 | a++; | |
309 | /* (Step 2) m = (w-1) / 2^a */ | |
310 | if (!BN_rshift(m, w1, a)) | |
0f113f3e MC |
311 | goto err; |
312 | ||
8b24f942 | 313 | /* Montgomery setup for computations mod a */ |
0f113f3e | 314 | mont = BN_MONT_CTX_new(); |
8240d5fa | 315 | if (mont == NULL || !BN_MONT_CTX_set(mont, w, ctx)) |
0f113f3e MC |
316 | goto err; |
317 | ||
8240d5fa SL |
318 | if (iterations == BN_prime_checks) |
319 | iterations = BN_prime_checks_for_size(BN_num_bits(w)); | |
0f113f3e | 320 | |
8240d5fa SL |
321 | /* (Step 4) */ |
322 | for (i = 0; i < iterations; ++i) { | |
323 | /* (Step 4.1) obtain a Random string of bits b where 1 < b < w-1 */ | |
2934be91 MC |
324 | if (!BN_priv_rand_range_ex(b, w3, ctx) |
325 | || !BN_add_word(b, 2)) /* 1 < b < w-1 */ | |
0f113f3e | 326 | goto err; |
8240d5fa SL |
327 | |
328 | if (enhanced) { | |
329 | /* (Step 4.3) */ | |
330 | if (!BN_gcd(g, b, w, ctx)) | |
331 | goto err; | |
332 | /* (Step 4.4) */ | |
333 | if (!BN_is_one(g)) { | |
334 | *status = BN_PRIMETEST_COMPOSITE_WITH_FACTOR; | |
335 | ret = 1; | |
336 | goto err; | |
337 | } | |
338 | } | |
339 | /* (Step 4.5) z = b^m mod w */ | |
340 | if (!BN_mod_exp_mont(z, b, m, w, ctx, mont)) | |
0f113f3e | 341 | goto err; |
8240d5fa SL |
342 | /* (Step 4.6) if (z = 1 or z = w-1) */ |
343 | if (BN_is_one(z) || BN_cmp(z, w1) == 0) | |
344 | goto outer_loop; | |
345 | /* (Step 4.7) for j = 1 to a-1 */ | |
346 | for (j = 1; j < a ; ++j) { | |
347 | /* (Step 4.7.1 - 4.7.2) x = z. z = x^2 mod w */ | |
348 | if (!BN_copy(x, z) || !BN_mod_mul(z, x, x, w, ctx)) | |
349 | goto err; | |
350 | /* (Step 4.7.3) */ | |
351 | if (BN_cmp(z, w1) == 0) | |
352 | goto outer_loop; | |
353 | /* (Step 4.7.4) */ | |
354 | if (BN_is_one(z)) | |
355 | goto composite; | |
0f113f3e | 356 | } |
8240d5fa SL |
357 | /* At this point z = b^((w-1)/2) mod w */ |
358 | /* (Steps 4.8 - 4.9) x = z, z = x^2 mod w */ | |
359 | if (!BN_copy(x, z) || !BN_mod_mul(z, x, x, w, ctx)) | |
360 | goto err; | |
361 | /* (Step 4.10) */ | |
362 | if (BN_is_one(z)) | |
363 | goto composite; | |
364 | /* (Step 4.11) x = b^(w-1) mod w */ | |
365 | if (!BN_copy(x, z)) | |
366 | goto err; | |
367 | composite: | |
368 | if (enhanced) { | |
369 | /* (Step 4.1.2) g = GCD(x-1, w) */ | |
370 | if (!BN_sub_word(x, 1) || !BN_gcd(g, x, w, ctx)) | |
371 | goto err; | |
372 | /* (Steps 4.1.3 - 4.1.4) */ | |
373 | if (BN_is_one(g)) | |
374 | *status = BN_PRIMETEST_COMPOSITE_NOT_POWER_OF_PRIME; | |
375 | else | |
376 | *status = BN_PRIMETEST_COMPOSITE_WITH_FACTOR; | |
377 | } else { | |
378 | *status = BN_PRIMETEST_COMPOSITE; | |
379 | } | |
380 | ret = 1; | |
381 | goto err; | |
382 | outer_loop: ; | |
383 | /* (Step 4.1.5) */ | |
3e3dcf9a KR |
384 | if (!BN_GENCB_call(cb, 1, i)) |
385 | goto err; | |
0f113f3e | 386 | } |
8240d5fa SL |
387 | /* (Step 5) */ |
388 | *status = BN_PRIMETEST_PROBABLY_PRIME; | |
0f113f3e | 389 | ret = 1; |
8240d5fa SL |
390 | err: |
391 | BN_clear(g); | |
392 | BN_clear(w1); | |
393 | BN_clear(w3); | |
394 | BN_clear(x); | |
395 | BN_clear(m); | |
396 | BN_clear(z); | |
397 | BN_clear(b); | |
398 | BN_CTX_end(ctx); | |
23a1d5e9 | 399 | BN_MONT_CTX_free(mont); |
26a7d938 | 400 | return ret; |
0f113f3e | 401 | } |
a87030a1 | 402 | |
2934be91 | 403 | static int probable_prime(BIGNUM *rnd, int bits, prime_t *mods, BN_CTX *ctx) |
0f113f3e MC |
404 | { |
405 | int i; | |
0f113f3e MC |
406 | BN_ULONG delta; |
407 | BN_ULONG maxdelta = BN_MASK2 - primes[NUMPRIMES - 1]; | |
408 | char is_single_word = bits <= BN_BITS2; | |
409 | ||
410 | again: | |
4cffafe9 | 411 | /* TODO: Not all primes are private */ |
2934be91 | 412 | if (!BN_priv_rand_ex(rnd, bits, BN_RAND_TOP_TWO, BN_RAND_BOTTOM_ODD, ctx)) |
26a7d938 | 413 | return 0; |
0f113f3e | 414 | /* we now have a random number 'rnd' to test. */ |
d70a5627 DB |
415 | for (i = 1; i < NUMPRIMES; i++) { |
416 | BN_ULONG mod = BN_mod_word(rnd, (BN_ULONG)primes[i]); | |
417 | if (mod == (BN_ULONG)-1) | |
418 | return 0; | |
419 | mods[i] = (prime_t) mod; | |
420 | } | |
0f113f3e MC |
421 | /* |
422 | * If bits is so small that it fits into a single word then we | |
423 | * additionally don't want to exceed that many bits. | |
424 | */ | |
425 | if (is_single_word) { | |
e4676e90 | 426 | BN_ULONG size_limit; |
02e112a8 | 427 | |
e4676e90 MC |
428 | if (bits == BN_BITS2) { |
429 | /* | |
430 | * Shifting by this much has undefined behaviour so we do it a | |
431 | * different way | |
432 | */ | |
433 | size_limit = ~((BN_ULONG)0) - BN_get_word(rnd); | |
434 | } else { | |
435 | size_limit = (((BN_ULONG)1) << bits) - BN_get_word(rnd) - 1; | |
436 | } | |
0f113f3e MC |
437 | if (size_limit < maxdelta) |
438 | maxdelta = size_limit; | |
439 | } | |
440 | delta = 0; | |
441 | loop: | |
442 | if (is_single_word) { | |
443 | BN_ULONG rnd_word = BN_get_word(rnd); | |
444 | ||
50e735f9 MC |
445 | /*- |
446 | * In the case that the candidate prime is a single word then | |
447 | * we check that: | |
448 | * 1) It's greater than primes[i] because we shouldn't reject | |
449 | * 3 as being a prime number because it's a multiple of | |
450 | * three. | |
451 | * 2) That it's not a multiple of a known prime. We don't | |
452 | * check that rnd-1 is also coprime to all the known | |
453 | * primes because there aren't many small primes where | |
454 | * that's true. | |
455 | */ | |
0f113f3e MC |
456 | for (i = 1; i < NUMPRIMES && primes[i] < rnd_word; i++) { |
457 | if ((mods[i] + delta) % primes[i] == 0) { | |
458 | delta += 2; | |
459 | if (delta > maxdelta) | |
460 | goto again; | |
461 | goto loop; | |
462 | } | |
463 | } | |
464 | } else { | |
465 | for (i = 1; i < NUMPRIMES; i++) { | |
466 | /* | |
467 | * check that rnd is not a prime and also that gcd(rnd-1,primes) | |
468 | * == 1 (except for 2) | |
469 | */ | |
470 | if (((mods[i] + delta) % primes[i]) <= 1) { | |
471 | delta += 2; | |
472 | if (delta > maxdelta) | |
473 | goto again; | |
474 | goto loop; | |
475 | } | |
476 | } | |
477 | } | |
478 | if (!BN_add_word(rnd, delta)) | |
26a7d938 | 479 | return 0; |
0f113f3e MC |
480 | if (BN_num_bits(rnd) != bits) |
481 | goto again; | |
482 | bn_check_top(rnd); | |
208fb891 | 483 | return 1; |
0f113f3e | 484 | } |
d02b48c6 | 485 | |
982c42cb | 486 | int bn_probable_prime_dh(BIGNUM *rnd, int bits, |
0f113f3e MC |
487 | const BIGNUM *add, const BIGNUM *rem, BN_CTX *ctx) |
488 | { | |
489 | int i, ret = 0; | |
490 | BIGNUM *t1; | |
491 | ||
492 | BN_CTX_start(ctx); | |
493 | if ((t1 = BN_CTX_get(ctx)) == NULL) | |
494 | goto err; | |
495 | ||
2934be91 | 496 | if (!BN_rand_ex(rnd, bits, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD, ctx)) |
0f113f3e MC |
497 | goto err; |
498 | ||
499 | /* we need ((rnd-rem) % add) == 0 */ | |
500 | ||
501 | if (!BN_mod(t1, rnd, add, ctx)) | |
502 | goto err; | |
503 | if (!BN_sub(rnd, rnd, t1)) | |
504 | goto err; | |
505 | if (rem == NULL) { | |
506 | if (!BN_add_word(rnd, 1)) | |
507 | goto err; | |
508 | } else { | |
509 | if (!BN_add(rnd, rnd, rem)) | |
510 | goto err; | |
511 | } | |
512 | ||
513 | /* we now have a random number 'rand' to test. */ | |
514 | ||
515 | loop: | |
516 | for (i = 1; i < NUMPRIMES; i++) { | |
517 | /* check that rnd is a prime */ | |
d70a5627 DB |
518 | BN_ULONG mod = BN_mod_word(rnd, (BN_ULONG)primes[i]); |
519 | if (mod == (BN_ULONG)-1) | |
520 | goto err; | |
521 | if (mod <= 1) { | |
0f113f3e MC |
522 | if (!BN_add(rnd, rnd, add)) |
523 | goto err; | |
524 | goto loop; | |
525 | } | |
526 | } | |
527 | ret = 1; | |
528 | ||
529 | err: | |
530 | BN_CTX_end(ctx); | |
531 | bn_check_top(rnd); | |
26a7d938 | 532 | return ret; |
0f113f3e | 533 | } |
b0513819 | 534 | |
020fc820 | 535 | static int probable_prime_dh_safe(BIGNUM *p, int bits, const BIGNUM *padd, |
0f113f3e MC |
536 | const BIGNUM *rem, BN_CTX *ctx) |
537 | { | |
538 | int i, ret = 0; | |
539 | BIGNUM *t1, *qadd, *q; | |
540 | ||
541 | bits--; | |
542 | BN_CTX_start(ctx); | |
543 | t1 = BN_CTX_get(ctx); | |
544 | q = BN_CTX_get(ctx); | |
545 | qadd = BN_CTX_get(ctx); | |
546 | if (qadd == NULL) | |
547 | goto err; | |
548 | ||
549 | if (!BN_rshift1(qadd, padd)) | |
550 | goto err; | |
551 | ||
2934be91 | 552 | if (!BN_rand_ex(q, bits, BN_RAND_TOP_ONE, BN_RAND_BOTTOM_ODD, ctx)) |
0f113f3e MC |
553 | goto err; |
554 | ||
555 | /* we need ((rnd-rem) % add) == 0 */ | |
556 | if (!BN_mod(t1, q, qadd, ctx)) | |
557 | goto err; | |
558 | if (!BN_sub(q, q, t1)) | |
559 | goto err; | |
560 | if (rem == NULL) { | |
561 | if (!BN_add_word(q, 1)) | |
562 | goto err; | |
563 | } else { | |
564 | if (!BN_rshift1(t1, rem)) | |
565 | goto err; | |
566 | if (!BN_add(q, q, t1)) | |
567 | goto err; | |
568 | } | |
569 | ||
570 | /* we now have a random number 'rand' to test. */ | |
571 | if (!BN_lshift1(p, q)) | |
572 | goto err; | |
573 | if (!BN_add_word(p, 1)) | |
574 | goto err; | |
575 | ||
576 | loop: | |
577 | for (i = 1; i < NUMPRIMES; i++) { | |
578 | /* check that p and q are prime */ | |
579 | /* | |
580 | * check that for p and q gcd(p-1,primes) == 1 (except for 2) | |
581 | */ | |
d70a5627 DB |
582 | BN_ULONG pmod = BN_mod_word(p, (BN_ULONG)primes[i]); |
583 | BN_ULONG qmod = BN_mod_word(q, (BN_ULONG)primes[i]); | |
584 | if (pmod == (BN_ULONG)-1 || qmod == (BN_ULONG)-1) | |
585 | goto err; | |
586 | if (pmod == 0 || qmod == 0) { | |
0f113f3e MC |
587 | if (!BN_add(p, p, padd)) |
588 | goto err; | |
589 | if (!BN_add(q, q, qadd)) | |
590 | goto err; | |
591 | goto loop; | |
592 | } | |
593 | } | |
594 | ret = 1; | |
595 | ||
596 | err: | |
597 | BN_CTX_end(ctx); | |
598 | bn_check_top(p); | |
26a7d938 | 599 | return ret; |
0f113f3e | 600 | } |