1 /* $OpenBSD: moduli.c,v 1.39 2023/03/02 06:41:56 dtucker Exp $ */
2 /*
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"
41
42 #ifdef WITH_OPENSSL
43
44 #include <sys/types.h>
45
46 #include <openssl/bn.h>
47 #include <openssl/dh.h>
48
49 #include <errno.h>
50 #include <stdio.h>
51 #include <stdlib.h>
52 #include <string.h>
53 #include <stdarg.h>
54 #include <time.h>
55 #include <unistd.h>
56 #include <limits.h>
57
58 #include "xmalloc.h"
59 #include "dh.h"
60 #include "log.h"
61 #include "misc.h"
62
63 #include "openbsd-compat/openssl-compat.h"
64
65 /*
66 * File output defines
67 */
68
69 /* need line long enough for largest moduli plus headers */
70 #define QLINESIZE (100+8192)
71
72 /*
73 * Size: decimal.
74 * Specifies the number of the most significant bit (0 to M).
75 * WARNING: internally, usually 1 to N.
76 */
77 #define QSIZE_MINIMUM (511)
78
79 /*
80 * Prime sieving defines
81 */
82
83 /* Constant: assuming 8 bit bytes and 32 bit words */
84 #define SHIFT_BIT (3)
85 #define SHIFT_BYTE (2)
86 #define SHIFT_WORD (SHIFT_BIT+SHIFT_BYTE)
87 #define SHIFT_MEGABYTE (20)
88 #define SHIFT_MEGAWORD (SHIFT_MEGABYTE-SHIFT_BYTE)
89
90 /*
91 * Using virtual memory can cause thrashing. This should be the largest
92 * number that is supported without a large amount of disk activity --
93 * that would increase the run time from hours to days or weeks!
94 */
95 #define LARGE_MINIMUM (8UL) /* megabytes */
96
97 /*
98 * Do not increase this number beyond the unsigned integer bit size.
99 * Due to a multiple of 4, it must be LESS than 128 (yielding 2**30 bits).
100 */
101 #define LARGE_MAXIMUM (127UL) /* megabytes */
102
103 /*
104 * Constant: when used with 32-bit integers, the largest sieve prime
105 * has to be less than 2**32.
106 */
107 #define SMALL_MAXIMUM (0xffffffffUL)
108
109 /* Constant: can sieve all primes less than 2**32, as 65537**2 > 2**32-1. */
110 #define TINY_NUMBER (1UL<<16)
111
112 /* Ensure enough bit space for testing 2*q. */
113 #define TEST_MAXIMUM (1UL<<16)
114 #define TEST_MINIMUM (QSIZE_MINIMUM + 1)
115 /* real TEST_MINIMUM (1UL << (SHIFT_WORD - TEST_POWER)) */
116 #define TEST_POWER (3) /* 2**n, n < SHIFT_WORD */
117
118 /* bit operations on 32-bit words */
119 #define BIT_CLEAR(a,n) ((a)[(n)>>SHIFT_WORD] &= ~(1L << ((n) & 31)))
120 #define BIT_SET(a,n) ((a)[(n)>>SHIFT_WORD] |= (1L << ((n) & 31)))
121 #define BIT_TEST(a,n) ((a)[(n)>>SHIFT_WORD] & (1L << ((n) & 31)))
122
123 /*
124 * Prime testing defines
125 */
126
127 /* Minimum number of primality tests to perform */
128 #define TRIAL_MINIMUM (4)
129
130 /*
131 * Sieving data (XXX - move to struct)
132 */
133
134 /* sieve 2**16 */
135 static u_int32_t *TinySieve, tinybits;
136
137 /* sieve 2**30 in 2**16 parts */
138 static u_int32_t *SmallSieve, smallbits, smallbase;
139
140 /* sieve relative to the initial value */
141 static u_int32_t *LargeSieve, largewords, largetries, largenumbers;
142 static u_int32_t largebits, largememory; /* megabytes */
143 static BIGNUM *largebase;
144
145 int gen_candidates(FILE *, u_int32_t, u_int32_t, BIGNUM *);
146 int prime_test(FILE *, FILE *, u_int32_t, u_int32_t, char *, unsigned long,
147 unsigned long);
148
149 /*
150 * print moduli out in consistent form,
151 */
152 static int
qfileout(FILE * ofile,u_int32_t otype,u_int32_t otests,u_int32_t otries,u_int32_t osize,u_int32_t ogenerator,BIGNUM * omodulus)153 qfileout(FILE * ofile, u_int32_t otype, u_int32_t otests, u_int32_t otries,
154 u_int32_t osize, u_int32_t ogenerator, BIGNUM * omodulus)
155 {
156 struct tm *gtm;
157 time_t time_now;
158 int res;
159
160 time(&time_now);
161 gtm = gmtime(&time_now);
162 if (gtm == NULL)
163 return -1;
164
165 res = fprintf(ofile, "%04d%02d%02d%02d%02d%02d %u %u %u %u %x ",
166 gtm->tm_year + 1900, gtm->tm_mon + 1, gtm->tm_mday,
167 gtm->tm_hour, gtm->tm_min, gtm->tm_sec,
168 otype, otests, otries, osize, ogenerator);
169
170 if (res < 0)
171 return (-1);
172
173 if (BN_print_fp(ofile, omodulus) < 1)
174 return (-1);
175
176 res = fprintf(ofile, "\n");
177 fflush(ofile);
178
179 return (res > 0 ? 0 : -1);
180 }
181
182
183 /*
184 ** Sieve p's and q's with small factors
185 */
186 static void
sieve_large(u_int32_t s32)187 sieve_large(u_int32_t s32)
188 {
189 u_int64_t r, u, s = s32;
190
191 debug3("sieve_large %u", s32);
192 largetries++;
193 /* r = largebase mod s */
194 r = BN_mod_word(largebase, s32);
195 if (r == 0)
196 u = 0; /* s divides into largebase exactly */
197 else
198 u = s - r; /* largebase+u is first entry divisible by s */
199
200 if (u < largebits * 2ULL) {
201 /*
202 * The sieve omits p's and q's divisible by 2, so ensure that
203 * largebase+u is odd. Then, step through the sieve in
204 * increments of 2*s
205 */
206 if (u & 0x1)
207 u += s; /* Make largebase+u odd, and u even */
208
209 /* Mark all multiples of 2*s */
210 for (u /= 2; u < largebits; u += s)
211 BIT_SET(LargeSieve, u);
212 }
213
214 /* r = p mod s */
215 r = (2 * r + 1) % s;
216 if (r == 0)
217 u = 0; /* s divides p exactly */
218 else
219 u = s - r; /* p+u is first entry divisible by s */
220
221 if (u < largebits * 4ULL) {
222 /*
223 * The sieve omits p's divisible by 4, so ensure that
224 * largebase+u is not. Then, step through the sieve in
225 * increments of 4*s
226 */
227 while (u & 0x3) {
228 if (SMALL_MAXIMUM - u < s)
229 return;
230 u += s;
231 }
232
233 /* Mark all multiples of 4*s */
234 for (u /= 4; u < largebits; u += s)
235 BIT_SET(LargeSieve, u);
236 }
237 }
238
239 /*
240 * list candidates for Sophie-Germain primes (where q = (p-1)/2)
241 * to standard output.
242 * The list is checked against small known primes (less than 2**30).
243 */
244 int
gen_candidates(FILE * out,u_int32_t memory,u_int32_t power,BIGNUM * start)245 gen_candidates(FILE *out, u_int32_t memory, u_int32_t power, BIGNUM *start)
246 {
247 BIGNUM *q;
248 u_int32_t j, r, s, t;
249 u_int32_t smallwords = TINY_NUMBER >> 6;
250 u_int32_t tinywords = TINY_NUMBER >> 6;
251 time_t time_start, time_stop;
252 u_int32_t i;
253 int ret = 0;
254
255 largememory = memory;
256
257 if (memory != 0 &&
258 (memory < LARGE_MINIMUM || memory > LARGE_MAXIMUM)) {
259 error("Invalid memory amount (min %ld, max %ld)",
260 LARGE_MINIMUM, LARGE_MAXIMUM);
261 return (-1);
262 }
263
264 /*
265 * Set power to the length in bits of the prime to be generated.
266 * This is changed to 1 less than the desired safe prime moduli p.
267 */
268 if (power > TEST_MAXIMUM) {
269 error("Too many bits: %u > %lu", power, TEST_MAXIMUM);
270 return (-1);
271 } else if (power < TEST_MINIMUM) {
272 error("Too few bits: %u < %u", power, TEST_MINIMUM);
273 return (-1);
274 }
275 power--; /* decrement before squaring */
276
277 /*
278 * The density of ordinary primes is on the order of 1/bits, so the
279 * density of safe primes should be about (1/bits)**2. Set test range
280 * to something well above bits**2 to be reasonably sure (but not
281 * guaranteed) of catching at least one safe prime.
282 */
283 largewords = ((power * power) >> (SHIFT_WORD - TEST_POWER));
284
285 /*
286 * Need idea of how much memory is available. We don't have to use all
287 * of it.
288 */
289 if (largememory > LARGE_MAXIMUM) {
290 logit("Limited memory: %u MB; limit %lu MB",
291 largememory, LARGE_MAXIMUM);
292 largememory = LARGE_MAXIMUM;
293 }
294
295 if (largewords <= (largememory << SHIFT_MEGAWORD)) {
296 logit("Increased memory: %u MB; need %u bytes",
297 largememory, (largewords << SHIFT_BYTE));
298 largewords = (largememory << SHIFT_MEGAWORD);
299 } else if (largememory > 0) {
300 logit("Decreased memory: %u MB; want %u bytes",
301 largememory, (largewords << SHIFT_BYTE));
302 largewords = (largememory << SHIFT_MEGAWORD);
303 }
304
305 TinySieve = xcalloc(tinywords, sizeof(u_int32_t));
306 tinybits = tinywords << SHIFT_WORD;
307
308 SmallSieve = xcalloc(smallwords, sizeof(u_int32_t));
309 smallbits = smallwords << SHIFT_WORD;
310
311 /*
312 * dynamically determine available memory
313 */
314 while ((LargeSieve = calloc(largewords, sizeof(u_int32_t))) == NULL)
315 largewords -= (1L << (SHIFT_MEGAWORD - 2)); /* 1/4 MB chunks */
316
317 largebits = largewords << SHIFT_WORD;
318 largenumbers = largebits * 2; /* even numbers excluded */
319
320 /* validation check: count the number of primes tried */
321 largetries = 0;
322 if ((q = BN_new()) == NULL)
323 fatal("BN_new failed");
324
325 /*
326 * Generate random starting point for subprime search, or use
327 * specified parameter.
328 */
329 if ((largebase = BN_new()) == NULL)
330 fatal("BN_new failed");
331 if (start == NULL) {
332 if (BN_rand(largebase, power, 1, 1) == 0)
333 fatal("BN_rand failed");
334 } else {
335 if (BN_copy(largebase, start) == NULL)
336 fatal("BN_copy: failed");
337 }
338
339 /* ensure odd */
340 if (BN_set_bit(largebase, 0) == 0)
341 fatal("BN_set_bit: failed");
342
343 time(&time_start);
344
345 logit("%.24s Sieve next %u plus %u-bit", ctime(&time_start),
346 largenumbers, power);
347 debug2("start point: 0x%s", BN_bn2hex(largebase));
348
349 /*
350 * TinySieve
351 */
352 for (i = 0; i < tinybits; i++) {
353 if (BIT_TEST(TinySieve, i))
354 continue; /* 2*i+3 is composite */
355
356 /* The next tiny prime */
357 t = 2 * i + 3;
358
359 /* Mark all multiples of t */
360 for (j = i + t; j < tinybits; j += t)
361 BIT_SET(TinySieve, j);
362
363 sieve_large(t);
364 }
365
366 /*
367 * Start the small block search at the next possible prime. To avoid
368 * fencepost errors, the last pass is skipped.
369 */
370 for (smallbase = TINY_NUMBER + 3;
371 smallbase < (SMALL_MAXIMUM - TINY_NUMBER);
372 smallbase += TINY_NUMBER) {
373 for (i = 0; i < tinybits; i++) {
374 if (BIT_TEST(TinySieve, i))
375 continue; /* 2*i+3 is composite */
376
377 /* The next tiny prime */
378 t = 2 * i + 3;
379 r = smallbase % t;
380
381 if (r == 0) {
382 s = 0; /* t divides into smallbase exactly */
383 } else {
384 /* smallbase+s is first entry divisible by t */
385 s = t - r;
386 }
387
388 /*
389 * The sieve omits even numbers, so ensure that
390 * smallbase+s is odd. Then, step through the sieve
391 * in increments of 2*t
392 */
393 if (s & 1)
394 s += t; /* Make smallbase+s odd, and s even */
395
396 /* Mark all multiples of 2*t */
397 for (s /= 2; s < smallbits; s += t)
398 BIT_SET(SmallSieve, s);
399 }
400
401 /*
402 * SmallSieve
403 */
404 for (i = 0; i < smallbits; i++) {
405 if (BIT_TEST(SmallSieve, i))
406 continue; /* 2*i+smallbase is composite */
407
408 /* The next small prime */
409 sieve_large((2 * i) + smallbase);
410 }
411
412 memset(SmallSieve, 0, smallwords << SHIFT_BYTE);
413 }
414
415 time(&time_stop);
416
417 logit("%.24s Sieved with %u small primes in %lld seconds",
418 ctime(&time_stop), largetries, (long long)(time_stop - time_start));
419
420 for (j = r = 0; j < largebits; j++) {
421 if (BIT_TEST(LargeSieve, j))
422 continue; /* Definitely composite, skip */
423
424 debug2("test q = largebase+%u", 2 * j);
425 if (BN_set_word(q, 2 * j) == 0)
426 fatal("BN_set_word failed");
427 if (BN_add(q, q, largebase) == 0)
428 fatal("BN_add failed");
429 if (qfileout(out, MODULI_TYPE_SOPHIE_GERMAIN,
430 MODULI_TESTS_SIEVE, largetries,
431 (power - 1) /* MSB */, (0), q) == -1) {
432 ret = -1;
433 break;
434 }
435
436 r++; /* count q */
437 }
438
439 time(&time_stop);
440
441 free(LargeSieve);
442 free(SmallSieve);
443 free(TinySieve);
444
445 logit("%.24s Found %u candidates", ctime(&time_stop), r);
446
447 return (ret);
448 }
449
450 static void
write_checkpoint(char * cpfile,u_int32_t lineno)451 write_checkpoint(char *cpfile, u_int32_t lineno)
452 {
453 FILE *fp;
454 char tmp[PATH_MAX];
455 int r, writeok, closeok;
456
457 r = snprintf(tmp, sizeof(tmp), "%s.XXXXXXXXXX", cpfile);
458 if (r < 0 || r >= PATH_MAX) {
459 logit("write_checkpoint: temp pathname too long");
460 return;
461 }
462 if ((r = mkstemp(tmp)) == -1) {
463 logit("mkstemp(%s): %s", tmp, strerror(errno));
464 return;
465 }
466 if ((fp = fdopen(r, "w")) == NULL) {
467 logit("write_checkpoint: fdopen: %s", strerror(errno));
468 unlink(tmp);
469 close(r);
470 return;
471 }
472 writeok = (fprintf(fp, "%lu\n", (unsigned long)lineno) > 0);
473 closeok = (fclose(fp) == 0);
474 if (writeok && closeok && rename(tmp, cpfile) == 0) {
475 debug3("wrote checkpoint line %lu to '%s'",
476 (unsigned long)lineno, cpfile);
477 } else {
478 logit("failed to write to checkpoint file '%s': %s", cpfile,
479 strerror(errno));
480 (void)unlink(tmp);
481 }
482 }
483
484 static unsigned long
read_checkpoint(char * cpfile)485 read_checkpoint(char *cpfile)
486 {
487 FILE *fp;
488 unsigned long lineno = 0;
489
490 if ((fp = fopen(cpfile, "r")) == NULL)
491 return 0;
492 if (fscanf(fp, "%lu\n", &lineno) < 1)
493 logit("Failed to load checkpoint from '%s'", cpfile);
494 else
495 logit("Loaded checkpoint from '%s' line %lu", cpfile, lineno);
496 fclose(fp);
497 return lineno;
498 }
499
500 static unsigned long
count_lines(FILE * f)501 count_lines(FILE *f)
502 {
503 unsigned long count = 0;
504 char lp[QLINESIZE + 1];
505
506 if (fseek(f, 0, SEEK_SET) != 0) {
507 debug("input file is not seekable");
508 return ULONG_MAX;
509 }
510 while (fgets(lp, QLINESIZE + 1, f) != NULL)
511 count++;
512 rewind(f);
513 debug("input file has %lu lines", count);
514 return count;
515 }
516
517 static char *
fmt_time(time_t seconds)518 fmt_time(time_t seconds)
519 {
520 int day, hr, min;
521 static char buf[128];
522
523 min = (seconds / 60) % 60;
524 hr = (seconds / 60 / 60) % 24;
525 day = seconds / 60 / 60 / 24;
526 if (day > 0)
527 snprintf(buf, sizeof buf, "%dd %d:%02d", day, hr, min);
528 else
529 snprintf(buf, sizeof buf, "%d:%02d", hr, min);
530 return buf;
531 }
532
533 static void
print_progress(unsigned long start_lineno,unsigned long current_lineno,unsigned long end_lineno)534 print_progress(unsigned long start_lineno, unsigned long current_lineno,
535 unsigned long end_lineno)
536 {
537 static time_t time_start, time_prev;
538 time_t time_now, elapsed;
539 unsigned long num_to_process, processed, remaining, percent, eta;
540 double time_per_line;
541 char *eta_str;
542
543 time_now = monotime();
544 if (time_start == 0) {
545 time_start = time_prev = time_now;
546 return;
547 }
548 /* print progress after 1m then once per 5m */
549 if (time_now - time_prev < 5 * 60)
550 return;
551 time_prev = time_now;
552 elapsed = time_now - time_start;
553 processed = current_lineno - start_lineno;
554 remaining = end_lineno - current_lineno;
555 num_to_process = end_lineno - start_lineno;
556 time_per_line = (double)elapsed / processed;
557 /* if we don't know how many we're processing just report count+time */
558 time(&time_now);
559 if (end_lineno == ULONG_MAX) {
560 logit("%.24s processed %lu in %s", ctime(&time_now),
561 processed, fmt_time(elapsed));
562 return;
563 }
564 percent = 100 * processed / num_to_process;
565 eta = time_per_line * remaining;
566 eta_str = xstrdup(fmt_time(eta));
567 logit("%.24s processed %lu of %lu (%lu%%) in %s, ETA %s",
568 ctime(&time_now), processed, num_to_process, percent,
569 fmt_time(elapsed), eta_str);
570 free(eta_str);
571 }
572
573 /*
574 * perform a Miller-Rabin primality test
575 * on the list of candidates
576 * (checking both q and p)
577 * The result is a list of so-call "safe" primes
578 */
579 int
prime_test(FILE * in,FILE * out,u_int32_t trials,u_int32_t generator_wanted,char * checkpoint_file,unsigned long start_lineno,unsigned long num_lines)580 prime_test(FILE *in, FILE *out, u_int32_t trials, u_int32_t generator_wanted,
581 char *checkpoint_file, unsigned long start_lineno, unsigned long num_lines)
582 {
583 BIGNUM *q, *p, *a;
584 char *cp, *lp;
585 u_int32_t count_in = 0, count_out = 0, count_possible = 0;
586 u_int32_t generator_known, in_tests, in_tries, in_type, in_size;
587 unsigned long last_processed = 0, end_lineno;
588 time_t time_start, time_stop;
589 int res, is_prime;
590
591 if (trials < TRIAL_MINIMUM) {
592 error("Minimum primality trials is %d", TRIAL_MINIMUM);
593 return (-1);
594 }
595
596 if (num_lines == 0)
597 end_lineno = count_lines(in);
598 else
599 end_lineno = start_lineno + num_lines;
600
601 time(&time_start);
602
603 if ((p = BN_new()) == NULL)
604 fatal("BN_new failed");
605 if ((q = BN_new()) == NULL)
606 fatal("BN_new failed");
607
608 debug2("%.24s Final %u Miller-Rabin trials (%x generator)",
609 ctime(&time_start), trials, generator_wanted);
610
611 if (checkpoint_file != NULL)
612 last_processed = read_checkpoint(checkpoint_file);
613 last_processed = start_lineno = MAXIMUM(last_processed, start_lineno);
614 if (end_lineno == ULONG_MAX)
615 debug("process from line %lu from pipe", last_processed);
616 else
617 debug("process from line %lu to line %lu", last_processed,
618 end_lineno);
619
620 res = 0;
621 lp = xmalloc(QLINESIZE + 1);
622 while (fgets(lp, QLINESIZE + 1, in) != NULL && count_in < end_lineno) {
623 count_in++;
624 if (count_in <= last_processed) {
625 debug3("skipping line %u, before checkpoint or "
626 "specified start line", count_in);
627 continue;
628 }
629 if (checkpoint_file != NULL)
630 write_checkpoint(checkpoint_file, count_in);
631 print_progress(start_lineno, count_in, end_lineno);
632 if (strlen(lp) < 14 || *lp == '!' || *lp == '#') {
633 debug2("%10u: comment or short line", count_in);
634 continue;
635 }
636
637 /* XXX - fragile parser */
638 /* time */
639 cp = &lp[14]; /* (skip) */
640
641 /* type */
642 in_type = strtoul(cp, &cp, 10);
643
644 /* tests */
645 in_tests = strtoul(cp, &cp, 10);
646
647 if (in_tests & MODULI_TESTS_COMPOSITE) {
648 debug2("%10u: known composite", count_in);
649 continue;
650 }
651
652 /* tries */
653 in_tries = strtoul(cp, &cp, 10);
654
655 /* size (most significant bit) */
656 in_size = strtoul(cp, &cp, 10);
657
658 /* generator (hex) */
659 generator_known = strtoul(cp, &cp, 16);
660
661 /* Skip white space */
662 cp += strspn(cp, " ");
663
664 /* modulus (hex) */
665 switch (in_type) {
666 case MODULI_TYPE_SOPHIE_GERMAIN:
667 debug2("%10u: (%u) Sophie-Germain", count_in, in_type);
668 a = q;
669 if (BN_hex2bn(&a, cp) == 0)
670 fatal("BN_hex2bn failed");
671 /* p = 2*q + 1 */
672 if (BN_lshift(p, q, 1) == 0)
673 fatal("BN_lshift failed");
674 if (BN_add_word(p, 1) == 0)
675 fatal("BN_add_word failed");
676 in_size += 1;
677 generator_known = 0;
678 break;
679 case MODULI_TYPE_UNSTRUCTURED:
680 case MODULI_TYPE_SAFE:
681 case MODULI_TYPE_SCHNORR:
682 case MODULI_TYPE_STRONG:
683 case MODULI_TYPE_UNKNOWN:
684 debug2("%10u: (%u)", count_in, in_type);
685 a = p;
686 if (BN_hex2bn(&a, cp) == 0)
687 fatal("BN_hex2bn failed");
688 /* q = (p-1) / 2 */
689 if (BN_rshift(q, p, 1) == 0)
690 fatal("BN_rshift failed");
691 break;
692 default:
693 debug2("Unknown prime type");
694 break;
695 }
696
697 /*
698 * due to earlier inconsistencies in interpretation, check
699 * the proposed bit size.
700 */
701 if ((u_int32_t)BN_num_bits(p) != (in_size + 1)) {
702 debug2("%10u: bit size %u mismatch", count_in, in_size);
703 continue;
704 }
705 if (in_size < QSIZE_MINIMUM) {
706 debug2("%10u: bit size %u too short", count_in, in_size);
707 continue;
708 }
709
710 if (in_tests & MODULI_TESTS_MILLER_RABIN)
711 in_tries += trials;
712 else
713 in_tries = trials;
714
715 /*
716 * guess unknown generator
717 */
718 if (generator_known == 0) {
719 if (BN_mod_word(p, 24) == 11)
720 generator_known = 2;
721 else {
722 u_int32_t r = BN_mod_word(p, 10);
723
724 if (r == 3 || r == 7)
725 generator_known = 5;
726 }
727 }
728 /*
729 * skip tests when desired generator doesn't match
730 */
731 if (generator_wanted > 0 &&
732 generator_wanted != generator_known) {
733 debug2("%10u: generator %d != %d",
734 count_in, generator_known, generator_wanted);
735 continue;
736 }
737
738 /*
739 * Primes with no known generator are useless for DH, so
740 * skip those.
741 */
742 if (generator_known == 0) {
743 debug2("%10u: no known generator", count_in);
744 continue;
745 }
746
747 count_possible++;
748
749 /*
750 * The (1/4)^N performance bound on Miller-Rabin is
751 * extremely pessimistic, so don't spend a lot of time
752 * really verifying that q is prime until after we know
753 * that p is also prime. A single pass will weed out the
754 * vast majority of composite q's.
755 */
756 is_prime = BN_is_prime_ex(q, 1, NULL, NULL);
757 if (is_prime < 0)
758 fatal("BN_is_prime_ex failed");
759 if (is_prime == 0) {
760 debug("%10u: q failed first possible prime test",
761 count_in);
762 continue;
763 }
764
765 /*
766 * q is possibly prime, so go ahead and really make sure
767 * that p is prime. If it is, then we can go back and do
768 * the same for q. If p is composite, chances are that
769 * will show up on the first Rabin-Miller iteration so it
770 * doesn't hurt to specify a high iteration count.
771 */
772 is_prime = BN_is_prime_ex(p, trials, NULL, NULL);
773 if (is_prime < 0)
774 fatal("BN_is_prime_ex failed");
775 if (is_prime == 0) {
776 debug("%10u: p is not prime", count_in);
777 continue;
778 }
779 debug("%10u: p is almost certainly prime", count_in);
780
781 /* recheck q more rigorously */
782 is_prime = BN_is_prime_ex(q, trials - 1, NULL, NULL);
783 if (is_prime < 0)
784 fatal("BN_is_prime_ex failed");
785 if (is_prime == 0) {
786 debug("%10u: q is not prime", count_in);
787 continue;
788 }
789 debug("%10u: q is almost certainly prime", count_in);
790
791 if (qfileout(out, MODULI_TYPE_SAFE,
792 in_tests | MODULI_TESTS_MILLER_RABIN,
793 in_tries, in_size, generator_known, p)) {
794 res = -1;
795 break;
796 }
797
798 count_out++;
799 }
800
801 time(&time_stop);
802 free(lp);
803 BN_free(p);
804 BN_free(q);
805
806 if (checkpoint_file != NULL)
807 unlink(checkpoint_file);
808
809 logit("%.24s Found %u safe primes of %u candidates in %ld seconds",
810 ctime(&time_stop), count_out, count_possible,
811 (long) (time_stop - time_start));
812
813 return (res);
814 }
815
816 #endif /* WITH_OPENSSL */
817