blob: f6f15a2a40c24cf8c42c062f9f2ee78759c6dcbe [file] [log] [blame]
Damien Miller07d86be2006-03-26 14:19:21 +11001/* $OpenBSD: moduli.c,v 1.13 2006/03/25 00:05:41 djm Exp $ */
Darren Tuckerb2f9d412003-08-02 23:51:38 +10002/*
3 * Copyright 1994 Phil Karn <karn@qualcomm.com>
4 * Copyright 1996-1998, 2003 William Allen Simpson <wsimpson@greendragon.com>
5 * Copyright 2000 Niels Provos <provos@citi.umich.edu>
6 * All rights reserved.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 * notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 * notice, this list of conditions and the following disclaimer in the
15 * documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
18 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
19 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
20 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
21 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
22 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
23 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
24 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
25 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
26 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
27 */
28
29/*
30 * Two-step process to generate safe primes for DHGEX
31 *
32 * Sieve candidates for "safe" primes,
33 * suitable for use as Diffie-Hellman moduli;
34 * that is, where q = (p-1)/2 is also prime.
35 *
36 * First step: generate candidate primes (memory intensive)
37 * Second step: test primes' safety (processor intensive)
38 */
39
40#include "includes.h"
Darren Tuckerb2f9d412003-08-02 23:51:38 +100041#include "xmalloc.h"
42#include "log.h"
43
44#include <openssl/bn.h>
45
Darren Tuckerb2f9d412003-08-02 23:51:38 +100046/*
47 * File output defines
48 */
49
50/* need line long enough for largest moduli plus headers */
Darren Tuckerfc959702004-07-17 16:12:08 +100051#define QLINESIZE (100+8192)
Darren Tuckerb2f9d412003-08-02 23:51:38 +100052
53/* Type: decimal.
54 * Specifies the internal structure of the prime modulus.
55 */
Darren Tuckerfc959702004-07-17 16:12:08 +100056#define QTYPE_UNKNOWN (0)
57#define QTYPE_UNSTRUCTURED (1)
58#define QTYPE_SAFE (2)
Darren Tuckerf0e792e2005-01-20 11:02:26 +110059#define QTYPE_SCHNORR (3)
Darren Tuckerfc959702004-07-17 16:12:08 +100060#define QTYPE_SOPHIE_GERMAIN (4)
61#define QTYPE_STRONG (5)
Darren Tuckerb2f9d412003-08-02 23:51:38 +100062
63/* Tests: decimal (bit field).
64 * Specifies the methods used in checking for primality.
65 * Usually, more than one test is used.
66 */
Darren Tuckerfc959702004-07-17 16:12:08 +100067#define QTEST_UNTESTED (0x00)
68#define QTEST_COMPOSITE (0x01)
69#define QTEST_SIEVE (0x02)
70#define QTEST_MILLER_RABIN (0x04)
71#define QTEST_JACOBI (0x08)
72#define QTEST_ELLIPTIC (0x10)
Darren Tuckerb2f9d412003-08-02 23:51:38 +100073
Darren Tucker06930c72003-12-31 11:34:51 +110074/*
75 * Size: decimal.
Darren Tuckerb2f9d412003-08-02 23:51:38 +100076 * Specifies the number of the most significant bit (0 to M).
Darren Tucker06930c72003-12-31 11:34:51 +110077 * WARNING: internally, usually 1 to N.
Darren Tuckerb2f9d412003-08-02 23:51:38 +100078 */
Darren Tuckerfc959702004-07-17 16:12:08 +100079#define QSIZE_MINIMUM (511)
Darren Tuckerb2f9d412003-08-02 23:51:38 +100080
81/*
82 * Prime sieving defines
83 */
84
85/* Constant: assuming 8 bit bytes and 32 bit words */
Darren Tuckerfc959702004-07-17 16:12:08 +100086#define SHIFT_BIT (3)
87#define SHIFT_BYTE (2)
88#define SHIFT_WORD (SHIFT_BIT+SHIFT_BYTE)
89#define SHIFT_MEGABYTE (20)
90#define SHIFT_MEGAWORD (SHIFT_MEGABYTE-SHIFT_BYTE)
Darren Tuckerb2f9d412003-08-02 23:51:38 +100091
92/*
Darren Tucker770fc012004-05-13 16:24:32 +100093 * Using virtual memory can cause thrashing. This should be the largest
94 * number that is supported without a large amount of disk activity --
95 * that would increase the run time from hours to days or weeks!
96 */
Darren Tuckerfc959702004-07-17 16:12:08 +100097#define LARGE_MINIMUM (8UL) /* megabytes */
Darren Tucker770fc012004-05-13 16:24:32 +100098
99/*
100 * Do not increase this number beyond the unsigned integer bit size.
101 * Due to a multiple of 4, it must be LESS than 128 (yielding 2**30 bits).
102 */
Darren Tuckerfc959702004-07-17 16:12:08 +1000103#define LARGE_MAXIMUM (127UL) /* megabytes */
Darren Tucker770fc012004-05-13 16:24:32 +1000104
105/*
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000106 * Constant: when used with 32-bit integers, the largest sieve prime
107 * has to be less than 2**32.
108 */
Darren Tuckerfc959702004-07-17 16:12:08 +1000109#define SMALL_MAXIMUM (0xffffffffUL)
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000110
111/* Constant: can sieve all primes less than 2**32, as 65537**2 > 2**32-1. */
Darren Tuckerfc959702004-07-17 16:12:08 +1000112#define TINY_NUMBER (1UL<<16)
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000113
114/* Ensure enough bit space for testing 2*q. */
Damien Miller0dc1bef2005-07-17 17:22:45 +1000115#define TEST_MAXIMUM (1UL<<16)
116#define TEST_MINIMUM (QSIZE_MINIMUM + 1)
117/* real TEST_MINIMUM (1UL << (SHIFT_WORD - TEST_POWER)) */
118#define TEST_POWER (3) /* 2**n, n < SHIFT_WORD */
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000119
120/* bit operations on 32-bit words */
Damien Miller0dc1bef2005-07-17 17:22:45 +1000121#define BIT_CLEAR(a,n) ((a)[(n)>>SHIFT_WORD] &= ~(1L << ((n) & 31)))
122#define BIT_SET(a,n) ((a)[(n)>>SHIFT_WORD] |= (1L << ((n) & 31)))
123#define BIT_TEST(a,n) ((a)[(n)>>SHIFT_WORD] & (1L << ((n) & 31)))
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000124
125/*
126 * Prime testing defines
127 */
128
Darren Tucker770fc012004-05-13 16:24:32 +1000129/* Minimum number of primality tests to perform */
Damien Miller0dc1bef2005-07-17 17:22:45 +1000130#define TRIAL_MINIMUM (4)
Darren Tucker770fc012004-05-13 16:24:32 +1000131
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000132/*
133 * Sieving data (XXX - move to struct)
134 */
135
136/* sieve 2**16 */
137static u_int32_t *TinySieve, tinybits;
138
139/* sieve 2**30 in 2**16 parts */
140static u_int32_t *SmallSieve, smallbits, smallbase;
141
142/* sieve relative to the initial value */
143static u_int32_t *LargeSieve, largewords, largetries, largenumbers;
144static u_int32_t largebits, largememory; /* megabytes */
145static BIGNUM *largebase;
146
Damien Millerb089fb52005-05-26 12:16:18 +1000147int gen_candidates(FILE *, u_int32_t, u_int32_t, BIGNUM *);
Darren Tuckere4ab1152004-05-24 10:14:24 +1000148int prime_test(FILE *, FILE *, u_int32_t, u_int32_t);
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000149
150/*
151 * print moduli out in consistent form,
152 */
153static int
154qfileout(FILE * ofile, u_int32_t otype, u_int32_t otests, u_int32_t otries,
155 u_int32_t osize, u_int32_t ogenerator, BIGNUM * omodulus)
156{
157 struct tm *gtm;
158 time_t time_now;
159 int res;
160
161 time(&time_now);
162 gtm = gmtime(&time_now);
Damien Miller787b2ec2003-11-21 23:56:47 +1100163
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000164 res = fprintf(ofile, "%04d%02d%02d%02d%02d%02d %u %u %u %u %x ",
165 gtm->tm_year + 1900, gtm->tm_mon + 1, gtm->tm_mday,
166 gtm->tm_hour, gtm->tm_min, gtm->tm_sec,
167 otype, otests, otries, osize, ogenerator);
168
169 if (res < 0)
170 return (-1);
171
172 if (BN_print_fp(ofile, omodulus) < 1)
173 return (-1);
174
175 res = fprintf(ofile, "\n");
176 fflush(ofile);
177
178 return (res > 0 ? 0 : -1);
179}
180
181
182/*
183 ** Sieve p's and q's with small factors
184 */
185static void
186sieve_large(u_int32_t s)
187{
188 u_int32_t r, u;
189
Darren Tucker06930c72003-12-31 11:34:51 +1100190 debug3("sieve_large %u", s);
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000191 largetries++;
192 /* r = largebase mod s */
193 r = BN_mod_word(largebase, s);
194 if (r == 0)
195 u = 0; /* s divides into largebase exactly */
196 else
197 u = s - r; /* largebase+u is first entry divisible by s */
198
199 if (u < largebits * 2) {
200 /*
201 * The sieve omits p's and q's divisible by 2, so ensure that
202 * largebase+u is odd. Then, step through the sieve in
203 * increments of 2*s
204 */
205 if (u & 0x1)
206 u += s; /* Make largebase+u odd, and u even */
207
208 /* Mark all multiples of 2*s */
209 for (u /= 2; u < largebits; u += s)
210 BIT_SET(LargeSieve, u);
211 }
212
213 /* r = p mod s */
214 r = (2 * r + 1) % s;
215 if (r == 0)
216 u = 0; /* s divides p exactly */
217 else
218 u = s - r; /* p+u is first entry divisible by s */
219
220 if (u < largebits * 4) {
221 /*
222 * The sieve omits p's divisible by 4, so ensure that
223 * largebase+u is not. Then, step through the sieve in
224 * increments of 4*s
225 */
226 while (u & 0x3) {
227 if (SMALL_MAXIMUM - u < s)
228 return;
229 u += s;
230 }
231
232 /* Mark all multiples of 4*s */
233 for (u /= 4; u < largebits; u += s)
234 BIT_SET(LargeSieve, u);
235 }
236}
237
238/*
Darren Tucker47abce42004-05-02 22:09:00 +1000239 * list candidates for Sophie-Germain primes (where q = (p-1)/2)
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000240 * to standard output.
241 * The list is checked against small known primes (less than 2**30).
242 */
243int
Damien Millerb089fb52005-05-26 12:16:18 +1000244gen_candidates(FILE *out, u_int32_t memory, u_int32_t power, BIGNUM *start)
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000245{
246 BIGNUM *q;
247 u_int32_t j, r, s, t;
248 u_int32_t smallwords = TINY_NUMBER >> 6;
249 u_int32_t tinywords = TINY_NUMBER >> 6;
250 time_t time_start, time_stop;
Damien Millerb089fb52005-05-26 12:16:18 +1000251 u_int32_t i;
252 int ret = 0;
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000253
254 largememory = memory;
255
Darren Tucker770fc012004-05-13 16:24:32 +1000256 if (memory != 0 &&
Damien Miller0dc1bef2005-07-17 17:22:45 +1000257 (memory < LARGE_MINIMUM || memory > LARGE_MAXIMUM)) {
Darren Tucker770fc012004-05-13 16:24:32 +1000258 error("Invalid memory amount (min %ld, max %ld)",
259 LARGE_MINIMUM, LARGE_MAXIMUM);
260 return (-1);
261 }
262
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000263 /*
Damien Millera8e06ce2003-11-21 23:48:55 +1100264 * Set power to the length in bits of the prime to be generated.
265 * This is changed to 1 less than the desired safe prime moduli p.
266 */
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000267 if (power > TEST_MAXIMUM) {
268 error("Too many bits: %u > %lu", power, TEST_MAXIMUM);
269 return (-1);
270 } else if (power < TEST_MINIMUM) {
271 error("Too few bits: %u < %u", power, TEST_MINIMUM);
272 return (-1);
273 }
274 power--; /* decrement before squaring */
275
276 /*
Damien Millera8e06ce2003-11-21 23:48:55 +1100277 * The density of ordinary primes is on the order of 1/bits, so the
278 * density of safe primes should be about (1/bits)**2. Set test range
279 * to something well above bits**2 to be reasonably sure (but not
280 * guaranteed) of catching at least one safe prime.
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000281 */
282 largewords = ((power * power) >> (SHIFT_WORD - TEST_POWER));
283
284 /*
Damien Millera8e06ce2003-11-21 23:48:55 +1100285 * Need idea of how much memory is available. We don't have to use all
286 * of it.
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000287 */
288 if (largememory > LARGE_MAXIMUM) {
289 logit("Limited memory: %u MB; limit %lu MB",
290 largememory, LARGE_MAXIMUM);
291 largememory = LARGE_MAXIMUM;
292 }
293
294 if (largewords <= (largememory << SHIFT_MEGAWORD)) {
295 logit("Increased memory: %u MB; need %u bytes",
296 largememory, (largewords << SHIFT_BYTE));
297 largewords = (largememory << SHIFT_MEGAWORD);
298 } else if (largememory > 0) {
299 logit("Decreased memory: %u MB; want %u bytes",
300 largememory, (largewords << SHIFT_BYTE));
301 largewords = (largememory << SHIFT_MEGAWORD);
302 }
303
Damien Miller07d86be2006-03-26 14:19:21 +1100304 TinySieve = xcalloc(tinywords, sizeof(u_int32_t));
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000305 tinybits = tinywords << SHIFT_WORD;
306
Damien Miller07d86be2006-03-26 14:19:21 +1100307 SmallSieve = xcalloc(smallwords, sizeof(u_int32_t));
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000308 smallbits = smallwords << SHIFT_WORD;
309
310 /*
311 * dynamically determine available memory
312 */
313 while ((LargeSieve = calloc(largewords, sizeof(u_int32_t))) == NULL)
314 largewords -= (1L << (SHIFT_MEGAWORD - 2)); /* 1/4 MB chunks */
315
316 largebits = largewords << SHIFT_WORD;
317 largenumbers = largebits * 2; /* even numbers excluded */
318
319 /* validation check: count the number of primes tried */
320 largetries = 0;
321 q = BN_new();
322
323 /*
Damien Millera8e06ce2003-11-21 23:48:55 +1100324 * Generate random starting point for subprime search, or use
325 * specified parameter.
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000326 */
327 largebase = BN_new();
328 if (start == NULL)
329 BN_rand(largebase, power, 1, 1);
330 else
331 BN_copy(largebase, start);
332
333 /* ensure odd */
334 BN_set_bit(largebase, 0);
335
336 time(&time_start);
337
Damien Millera8e06ce2003-11-21 23:48:55 +1100338 logit("%.24s Sieve next %u plus %u-bit", ctime(&time_start),
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000339 largenumbers, power);
340 debug2("start point: 0x%s", BN_bn2hex(largebase));
341
342 /*
Damien Millera8e06ce2003-11-21 23:48:55 +1100343 * TinySieve
344 */
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000345 for (i = 0; i < tinybits; i++) {
346 if (BIT_TEST(TinySieve, i))
347 continue; /* 2*i+3 is composite */
348
349 /* The next tiny prime */
350 t = 2 * i + 3;
351
352 /* Mark all multiples of t */
353 for (j = i + t; j < tinybits; j += t)
354 BIT_SET(TinySieve, j);
355
356 sieve_large(t);
357 }
358
359 /*
Damien Millera8e06ce2003-11-21 23:48:55 +1100360 * Start the small block search at the next possible prime. To avoid
361 * fencepost errors, the last pass is skipped.
362 */
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000363 for (smallbase = TINY_NUMBER + 3;
Damien Miller0dc1bef2005-07-17 17:22:45 +1000364 smallbase < (SMALL_MAXIMUM - TINY_NUMBER);
365 smallbase += TINY_NUMBER) {
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000366 for (i = 0; i < tinybits; i++) {
367 if (BIT_TEST(TinySieve, i))
368 continue; /* 2*i+3 is composite */
369
370 /* The next tiny prime */
371 t = 2 * i + 3;
372 r = smallbase % t;
373
374 if (r == 0) {
375 s = 0; /* t divides into smallbase exactly */
376 } else {
377 /* smallbase+s is first entry divisible by t */
378 s = t - r;
379 }
380
381 /*
382 * The sieve omits even numbers, so ensure that
383 * smallbase+s is odd. Then, step through the sieve
384 * in increments of 2*t
385 */
386 if (s & 1)
387 s += t; /* Make smallbase+s odd, and s even */
388
389 /* Mark all multiples of 2*t */
390 for (s /= 2; s < smallbits; s += t)
391 BIT_SET(SmallSieve, s);
392 }
393
394 /*
Damien Millera8e06ce2003-11-21 23:48:55 +1100395 * SmallSieve
396 */
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000397 for (i = 0; i < smallbits; i++) {
398 if (BIT_TEST(SmallSieve, i))
399 continue; /* 2*i+smallbase is composite */
400
401 /* The next small prime */
402 sieve_large((2 * i) + smallbase);
403 }
404
405 memset(SmallSieve, 0, smallwords << SHIFT_BYTE);
406 }
407
408 time(&time_stop);
409
410 logit("%.24s Sieved with %u small primes in %ld seconds",
411 ctime(&time_stop), largetries, (long) (time_stop - time_start));
412
413 for (j = r = 0; j < largebits; j++) {
414 if (BIT_TEST(LargeSieve, j))
415 continue; /* Definitely composite, skip */
416
417 debug2("test q = largebase+%u", 2 * j);
418 BN_set_word(q, 2 * j);
419 BN_add(q, q, largebase);
Darren Tucker47abce42004-05-02 22:09:00 +1000420 if (qfileout(out, QTYPE_SOPHIE_GERMAIN, QTEST_SIEVE,
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000421 largetries, (power - 1) /* MSB */, (0), q) == -1) {
422 ret = -1;
423 break;
424 }
425
426 r++; /* count q */
427 }
428
429 time(&time_stop);
430
431 xfree(LargeSieve);
432 xfree(SmallSieve);
433 xfree(TinySieve);
434
435 logit("%.24s Found %u candidates", ctime(&time_stop), r);
436
437 return (ret);
438}
439
440/*
441 * perform a Miller-Rabin primality test
442 * on the list of candidates
443 * (checking both q and p)
444 * The result is a list of so-call "safe" primes
445 */
446int
Darren Tucker770fc012004-05-13 16:24:32 +1000447prime_test(FILE *in, FILE *out, u_int32_t trials, u_int32_t generator_wanted)
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000448{
449 BIGNUM *q, *p, *a;
450 BN_CTX *ctx;
451 char *cp, *lp;
452 u_int32_t count_in = 0, count_out = 0, count_possible = 0;
453 u_int32_t generator_known, in_tests, in_tries, in_type, in_size;
454 time_t time_start, time_stop;
455 int res;
456
Darren Tucker770fc012004-05-13 16:24:32 +1000457 if (trials < TRIAL_MINIMUM) {
458 error("Minimum primality trials is %d", TRIAL_MINIMUM);
459 return (-1);
460 }
461
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000462 time(&time_start);
463
464 p = BN_new();
465 q = BN_new();
466 ctx = BN_CTX_new();
467
468 debug2("%.24s Final %u Miller-Rabin trials (%x generator)",
469 ctime(&time_start), trials, generator_wanted);
470
471 res = 0;
472 lp = xmalloc(QLINESIZE + 1);
473 while (fgets(lp, QLINESIZE, in) != NULL) {
474 int ll = strlen(lp);
475
476 count_in++;
477 if (ll < 14 || *lp == '!' || *lp == '#') {
478 debug2("%10u: comment or short line", count_in);
479 continue;
480 }
481
482 /* XXX - fragile parser */
483 /* time */
484 cp = &lp[14]; /* (skip) */
485
486 /* type */
487 in_type = strtoul(cp, &cp, 10);
488
489 /* tests */
490 in_tests = strtoul(cp, &cp, 10);
491
492 if (in_tests & QTEST_COMPOSITE) {
493 debug2("%10u: known composite", count_in);
494 continue;
495 }
Darren Tucker06930c72003-12-31 11:34:51 +1100496
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000497 /* tries */
498 in_tries = strtoul(cp, &cp, 10);
499
500 /* size (most significant bit) */
501 in_size = strtoul(cp, &cp, 10);
502
503 /* generator (hex) */
504 generator_known = strtoul(cp, &cp, 16);
505
506 /* Skip white space */
507 cp += strspn(cp, " ");
508
509 /* modulus (hex) */
510 switch (in_type) {
Darren Tucker47abce42004-05-02 22:09:00 +1000511 case QTYPE_SOPHIE_GERMAIN:
512 debug2("%10u: (%u) Sophie-Germain", count_in, in_type);
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000513 a = q;
514 BN_hex2bn(&a, cp);
515 /* p = 2*q + 1 */
516 BN_lshift(p, q, 1);
517 BN_add_word(p, 1);
518 in_size += 1;
519 generator_known = 0;
520 break;
Darren Tucker06930c72003-12-31 11:34:51 +1100521 case QTYPE_UNSTRUCTURED:
522 case QTYPE_SAFE:
Darren Tuckerf0e792e2005-01-20 11:02:26 +1100523 case QTYPE_SCHNORR:
Darren Tucker06930c72003-12-31 11:34:51 +1100524 case QTYPE_STRONG:
525 case QTYPE_UNKNOWN:
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000526 debug2("%10u: (%u)", count_in, in_type);
527 a = p;
528 BN_hex2bn(&a, cp);
529 /* q = (p-1) / 2 */
530 BN_rshift(q, p, 1);
531 break;
Darren Tucker06930c72003-12-31 11:34:51 +1100532 default:
533 debug2("Unknown prime type");
534 break;
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000535 }
536
537 /*
538 * due to earlier inconsistencies in interpretation, check
539 * the proposed bit size.
540 */
Damien Millerb089fb52005-05-26 12:16:18 +1000541 if ((u_int32_t)BN_num_bits(p) != (in_size + 1)) {
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000542 debug2("%10u: bit size %u mismatch", count_in, in_size);
543 continue;
544 }
545 if (in_size < QSIZE_MINIMUM) {
546 debug2("%10u: bit size %u too short", count_in, in_size);
547 continue;
548 }
549
550 if (in_tests & QTEST_MILLER_RABIN)
551 in_tries += trials;
552 else
553 in_tries = trials;
Darren Tucker06930c72003-12-31 11:34:51 +1100554
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000555 /*
556 * guess unknown generator
557 */
558 if (generator_known == 0) {
559 if (BN_mod_word(p, 24) == 11)
560 generator_known = 2;
561 else if (BN_mod_word(p, 12) == 5)
562 generator_known = 3;
563 else {
564 u_int32_t r = BN_mod_word(p, 10);
565
Darren Tucker06930c72003-12-31 11:34:51 +1100566 if (r == 3 || r == 7)
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000567 generator_known = 5;
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000568 }
569 }
570 /*
571 * skip tests when desired generator doesn't match
572 */
573 if (generator_wanted > 0 &&
574 generator_wanted != generator_known) {
575 debug2("%10u: generator %d != %d",
576 count_in, generator_known, generator_wanted);
577 continue;
578 }
579
Darren Tucker5cd9d442003-12-10 00:54:38 +1100580 /*
581 * Primes with no known generator are useless for DH, so
582 * skip those.
583 */
584 if (generator_known == 0) {
585 debug2("%10u: no known generator", count_in);
586 continue;
587 }
588
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000589 count_possible++;
590
591 /*
Damien Millera8e06ce2003-11-21 23:48:55 +1100592 * The (1/4)^N performance bound on Miller-Rabin is
593 * extremely pessimistic, so don't spend a lot of time
594 * really verifying that q is prime until after we know
595 * that p is also prime. A single pass will weed out the
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000596 * vast majority of composite q's.
597 */
598 if (BN_is_prime(q, 1, NULL, ctx, NULL) <= 0) {
Darren Tucker06930c72003-12-31 11:34:51 +1100599 debug("%10u: q failed first possible prime test",
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000600 count_in);
601 continue;
602 }
Damien Miller787b2ec2003-11-21 23:56:47 +1100603
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000604 /*
Damien Millera8e06ce2003-11-21 23:48:55 +1100605 * q is possibly prime, so go ahead and really make sure
606 * that p is prime. If it is, then we can go back and do
607 * the same for q. If p is composite, chances are that
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000608 * will show up on the first Rabin-Miller iteration so it
609 * doesn't hurt to specify a high iteration count.
610 */
611 if (!BN_is_prime(p, trials, NULL, ctx, NULL)) {
Darren Tucker06930c72003-12-31 11:34:51 +1100612 debug("%10u: p is not prime", count_in);
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000613 continue;
614 }
615 debug("%10u: p is almost certainly prime", count_in);
616
617 /* recheck q more rigorously */
618 if (!BN_is_prime(q, trials - 1, NULL, ctx, NULL)) {
619 debug("%10u: q is not prime", count_in);
620 continue;
621 }
622 debug("%10u: q is almost certainly prime", count_in);
623
Damien Millera8e06ce2003-11-21 23:48:55 +1100624 if (qfileout(out, QTYPE_SAFE, (in_tests | QTEST_MILLER_RABIN),
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000625 in_tries, in_size, generator_known, p)) {
626 res = -1;
627 break;
628 }
629
630 count_out++;
631 }
632
633 time(&time_stop);
634 xfree(lp);
635 BN_free(p);
636 BN_free(q);
637 BN_CTX_free(ctx);
638
639 logit("%.24s Found %u safe primes of %u candidates in %ld seconds",
Damien Millera8e06ce2003-11-21 23:48:55 +1100640 ctime(&time_stop), count_out, count_possible,
Darren Tuckerb2f9d412003-08-02 23:51:38 +1000641 (long) (time_stop - time_start));
642
643 return (res);
644}