xref: /openssh-portable/moduli.c (revision fd1a9649)
1 /* $OpenBSD: moduli.c,v 1.37 2019/11/15 06:00:20 djm 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 s)187 sieve_large(u_int32_t s)
188 {
189 	u_int32_t r, u;
190 
191 	debug3("sieve_large %u", s);
192 	largetries++;
193 	/* r = largebase mod s */
194 	r = BN_mod_word(largebase, s);
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 * 2) {
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 * 4) {
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;
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 	if (fprintf(fp, "%lu\n", (unsigned long)lineno) > 0 && fclose(fp) == 0
473 	    && rename(tmp, cpfile) == 0)
474 		debug3("wrote checkpoint line %lu to '%s'",
475 		    (unsigned long)lineno, cpfile);
476 	else
477 		logit("failed to write to checkpoint file '%s': %s", cpfile,
478 		    strerror(errno));
479 }
480 
481 static unsigned long
read_checkpoint(char * cpfile)482 read_checkpoint(char *cpfile)
483 {
484 	FILE *fp;
485 	unsigned long lineno = 0;
486 
487 	if ((fp = fopen(cpfile, "r")) == NULL)
488 		return 0;
489 	if (fscanf(fp, "%lu\n", &lineno) < 1)
490 		logit("Failed to load checkpoint from '%s'", cpfile);
491 	else
492 		logit("Loaded checkpoint from '%s' line %lu", cpfile, lineno);
493 	fclose(fp);
494 	return lineno;
495 }
496 
497 static unsigned long
count_lines(FILE * f)498 count_lines(FILE *f)
499 {
500 	unsigned long count = 0;
501 	char lp[QLINESIZE + 1];
502 
503 	if (fseek(f, 0, SEEK_SET) != 0) {
504 		debug("input file is not seekable");
505 		return ULONG_MAX;
506 	}
507 	while (fgets(lp, QLINESIZE + 1, f) != NULL)
508 		count++;
509 	rewind(f);
510 	debug("input file has %lu lines", count);
511 	return count;
512 }
513 
514 static char *
fmt_time(time_t seconds)515 fmt_time(time_t seconds)
516 {
517 	int day, hr, min;
518 	static char buf[128];
519 
520 	min = (seconds / 60) % 60;
521 	hr = (seconds / 60 / 60) % 24;
522 	day = seconds / 60 / 60 / 24;
523 	if (day > 0)
524 		snprintf(buf, sizeof buf, "%dd %d:%02d", day, hr, min);
525 	else
526 		snprintf(buf, sizeof buf, "%d:%02d", hr, min);
527 	return buf;
528 }
529 
530 static void
print_progress(unsigned long start_lineno,unsigned long current_lineno,unsigned long end_lineno)531 print_progress(unsigned long start_lineno, unsigned long current_lineno,
532     unsigned long end_lineno)
533 {
534 	static time_t time_start, time_prev;
535 	time_t time_now, elapsed;
536 	unsigned long num_to_process, processed, remaining, percent, eta;
537 	double time_per_line;
538 	char *eta_str;
539 
540 	time_now = monotime();
541 	if (time_start == 0) {
542 		time_start = time_prev = time_now;
543 		return;
544 	}
545 	/* print progress after 1m then once per 5m */
546 	if (time_now - time_prev < 5 * 60)
547 		return;
548 	time_prev = time_now;
549 	elapsed = time_now - time_start;
550 	processed = current_lineno - start_lineno;
551 	remaining = end_lineno - current_lineno;
552 	num_to_process = end_lineno - start_lineno;
553 	time_per_line = (double)elapsed / processed;
554 	/* if we don't know how many we're processing just report count+time */
555 	time(&time_now);
556 	if (end_lineno == ULONG_MAX) {
557 		logit("%.24s processed %lu in %s", ctime(&time_now),
558 		    processed, fmt_time(elapsed));
559 		return;
560 	}
561 	percent = 100 * processed / num_to_process;
562 	eta = time_per_line * remaining;
563 	eta_str = xstrdup(fmt_time(eta));
564 	logit("%.24s processed %lu of %lu (%lu%%) in %s, ETA %s",
565 	    ctime(&time_now), processed, num_to_process, percent,
566 	    fmt_time(elapsed), eta_str);
567 	free(eta_str);
568 }
569 
570 /*
571  * perform a Miller-Rabin primality test
572  * on the list of candidates
573  * (checking both q and p)
574  * The result is a list of so-call "safe" primes
575  */
576 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)577 prime_test(FILE *in, FILE *out, u_int32_t trials, u_int32_t generator_wanted,
578     char *checkpoint_file, unsigned long start_lineno, unsigned long num_lines)
579 {
580 	BIGNUM *q, *p, *a;
581 	char *cp, *lp;
582 	u_int32_t count_in = 0, count_out = 0, count_possible = 0;
583 	u_int32_t generator_known, in_tests, in_tries, in_type, in_size;
584 	unsigned long last_processed = 0, end_lineno;
585 	time_t time_start, time_stop;
586 	int res, is_prime;
587 
588 	if (trials < TRIAL_MINIMUM) {
589 		error("Minimum primality trials is %d", TRIAL_MINIMUM);
590 		return (-1);
591 	}
592 
593 	if (num_lines == 0)
594 		end_lineno = count_lines(in);
595 	else
596 		end_lineno = start_lineno + num_lines;
597 
598 	time(&time_start);
599 
600 	if ((p = BN_new()) == NULL)
601 		fatal("BN_new failed");
602 	if ((q = BN_new()) == NULL)
603 		fatal("BN_new failed");
604 
605 	debug2("%.24s Final %u Miller-Rabin trials (%x generator)",
606 	    ctime(&time_start), trials, generator_wanted);
607 
608 	if (checkpoint_file != NULL)
609 		last_processed = read_checkpoint(checkpoint_file);
610 	last_processed = start_lineno = MAXIMUM(last_processed, start_lineno);
611 	if (end_lineno == ULONG_MAX)
612 		debug("process from line %lu from pipe", last_processed);
613 	else
614 		debug("process from line %lu to line %lu", last_processed,
615 		    end_lineno);
616 
617 	res = 0;
618 	lp = xmalloc(QLINESIZE + 1);
619 	while (fgets(lp, QLINESIZE + 1, in) != NULL && count_in < end_lineno) {
620 		count_in++;
621 		if (count_in <= last_processed) {
622 			debug3("skipping line %u, before checkpoint or "
623 			    "specified start line", count_in);
624 			continue;
625 		}
626 		if (checkpoint_file != NULL)
627 			write_checkpoint(checkpoint_file, count_in);
628 		print_progress(start_lineno, count_in, end_lineno);
629 		if (strlen(lp) < 14 || *lp == '!' || *lp == '#') {
630 			debug2("%10u: comment or short line", count_in);
631 			continue;
632 		}
633 
634 		/* XXX - fragile parser */
635 		/* time */
636 		cp = &lp[14];	/* (skip) */
637 
638 		/* type */
639 		in_type = strtoul(cp, &cp, 10);
640 
641 		/* tests */
642 		in_tests = strtoul(cp, &cp, 10);
643 
644 		if (in_tests & MODULI_TESTS_COMPOSITE) {
645 			debug2("%10u: known composite", count_in);
646 			continue;
647 		}
648 
649 		/* tries */
650 		in_tries = strtoul(cp, &cp, 10);
651 
652 		/* size (most significant bit) */
653 		in_size = strtoul(cp, &cp, 10);
654 
655 		/* generator (hex) */
656 		generator_known = strtoul(cp, &cp, 16);
657 
658 		/* Skip white space */
659 		cp += strspn(cp, " ");
660 
661 		/* modulus (hex) */
662 		switch (in_type) {
663 		case MODULI_TYPE_SOPHIE_GERMAIN:
664 			debug2("%10u: (%u) Sophie-Germain", count_in, in_type);
665 			a = q;
666 			if (BN_hex2bn(&a, cp) == 0)
667 				fatal("BN_hex2bn failed");
668 			/* p = 2*q + 1 */
669 			if (BN_lshift(p, q, 1) == 0)
670 				fatal("BN_lshift failed");
671 			if (BN_add_word(p, 1) == 0)
672 				fatal("BN_add_word failed");
673 			in_size += 1;
674 			generator_known = 0;
675 			break;
676 		case MODULI_TYPE_UNSTRUCTURED:
677 		case MODULI_TYPE_SAFE:
678 		case MODULI_TYPE_SCHNORR:
679 		case MODULI_TYPE_STRONG:
680 		case MODULI_TYPE_UNKNOWN:
681 			debug2("%10u: (%u)", count_in, in_type);
682 			a = p;
683 			if (BN_hex2bn(&a, cp) == 0)
684 				fatal("BN_hex2bn failed");
685 			/* q = (p-1) / 2 */
686 			if (BN_rshift(q, p, 1) == 0)
687 				fatal("BN_rshift failed");
688 			break;
689 		default:
690 			debug2("Unknown prime type");
691 			break;
692 		}
693 
694 		/*
695 		 * due to earlier inconsistencies in interpretation, check
696 		 * the proposed bit size.
697 		 */
698 		if ((u_int32_t)BN_num_bits(p) != (in_size + 1)) {
699 			debug2("%10u: bit size %u mismatch", count_in, in_size);
700 			continue;
701 		}
702 		if (in_size < QSIZE_MINIMUM) {
703 			debug2("%10u: bit size %u too short", count_in, in_size);
704 			continue;
705 		}
706 
707 		if (in_tests & MODULI_TESTS_MILLER_RABIN)
708 			in_tries += trials;
709 		else
710 			in_tries = trials;
711 
712 		/*
713 		 * guess unknown generator
714 		 */
715 		if (generator_known == 0) {
716 			if (BN_mod_word(p, 24) == 11)
717 				generator_known = 2;
718 			else {
719 				u_int32_t r = BN_mod_word(p, 10);
720 
721 				if (r == 3 || r == 7)
722 					generator_known = 5;
723 			}
724 		}
725 		/*
726 		 * skip tests when desired generator doesn't match
727 		 */
728 		if (generator_wanted > 0 &&
729 		    generator_wanted != generator_known) {
730 			debug2("%10u: generator %d != %d",
731 			    count_in, generator_known, generator_wanted);
732 			continue;
733 		}
734 
735 		/*
736 		 * Primes with no known generator are useless for DH, so
737 		 * skip those.
738 		 */
739 		if (generator_known == 0) {
740 			debug2("%10u: no known generator", count_in);
741 			continue;
742 		}
743 
744 		count_possible++;
745 
746 		/*
747 		 * The (1/4)^N performance bound on Miller-Rabin is
748 		 * extremely pessimistic, so don't spend a lot of time
749 		 * really verifying that q is prime until after we know
750 		 * that p is also prime. A single pass will weed out the
751 		 * vast majority of composite q's.
752 		 */
753 		is_prime = BN_is_prime_ex(q, 1, NULL, NULL);
754 		if (is_prime < 0)
755 			fatal("BN_is_prime_ex failed");
756 		if (is_prime == 0) {
757 			debug("%10u: q failed first possible prime test",
758 			    count_in);
759 			continue;
760 		}
761 
762 		/*
763 		 * q is possibly prime, so go ahead and really make sure
764 		 * that p is prime. If it is, then we can go back and do
765 		 * the same for q. If p is composite, chances are that
766 		 * will show up on the first Rabin-Miller iteration so it
767 		 * doesn't hurt to specify a high iteration count.
768 		 */
769 		is_prime = BN_is_prime_ex(p, trials, NULL, NULL);
770 		if (is_prime < 0)
771 			fatal("BN_is_prime_ex failed");
772 		if (is_prime == 0) {
773 			debug("%10u: p is not prime", count_in);
774 			continue;
775 		}
776 		debug("%10u: p is almost certainly prime", count_in);
777 
778 		/* recheck q more rigorously */
779 		is_prime = BN_is_prime_ex(q, trials - 1, NULL, NULL);
780 		if (is_prime < 0)
781 			fatal("BN_is_prime_ex failed");
782 		if (is_prime == 0) {
783 			debug("%10u: q is not prime", count_in);
784 			continue;
785 		}
786 		debug("%10u: q is almost certainly prime", count_in);
787 
788 		if (qfileout(out, MODULI_TYPE_SAFE,
789 		    in_tests | MODULI_TESTS_MILLER_RABIN,
790 		    in_tries, in_size, generator_known, p)) {
791 			res = -1;
792 			break;
793 		}
794 
795 		count_out++;
796 	}
797 
798 	time(&time_stop);
799 	free(lp);
800 	BN_free(p);
801 	BN_free(q);
802 
803 	if (checkpoint_file != NULL)
804 		unlink(checkpoint_file);
805 
806 	logit("%.24s Found %u safe primes of %u candidates in %ld seconds",
807 	    ctime(&time_stop), count_out, count_possible,
808 	    (long) (time_stop - time_start));
809 
810 	return (res);
811 }
812 
813 #endif /* WITH_OPENSSL */
814