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