1/*	$NetBSD: moduli.c,v 1.17 2023/07/26 17:58:15 christos Exp $	*/
2/* $OpenBSD: moduli.c,v 1.39 2023/03/02 06:41:56 dtucker Exp $ */
3/*
4 * Copyright 1994 Phil Karn <karn@qualcomm.com>
5 * Copyright 1996-1998, 2003 William Allen Simpson <wsimpson@greendragon.com>
6 * Copyright 2000 Niels Provos <provos@citi.umich.edu>
7 * All rights reserved.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 *
18 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
19 * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
20 * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
21 * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
22 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
23 * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
24 * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
25 * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
26 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
27 * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
28 */
29
30/*
31 * Two-step process to generate safe primes for DHGEX
32 *
33 *  Sieve candidates for "safe" primes,
34 *  suitable for use as Diffie-Hellman moduli;
35 *  that is, where q = (p-1)/2 is also prime.
36 *
37 * First step: generate candidate primes (memory intensive)
38 * Second step: test primes' safety (processor intensive)
39 */
40#include "includes.h"
41__RCSID("$NetBSD: moduli.c,v 1.17 2023/07/26 17:58:15 christos Exp $");
42
43#include <sys/types.h>
44
45#include <openssl/bn.h>
46#include <openssl/dh.h>
47
48#include <errno.h>
49#include <stdio.h>
50#include <stdlib.h>
51#include <string.h>
52#include <stdarg.h>
53#include <time.h>
54#include <unistd.h>
55#include <limits.h>
56
57#include "xmalloc.h"
58#include "dh.h"
59#include "log.h"
60#include "misc.h"
61
62/*
63 * File output defines
64 */
65
66/* need line long enough for largest moduli plus headers */
67#define QLINESIZE		(100+8192)
68
69/*
70 * Size: decimal.
71 * Specifies the number of the most significant bit (0 to M).
72 * WARNING: internally, usually 1 to N.
73 */
74#define QSIZE_MINIMUM		(511)
75
76/*
77 * Prime sieving defines
78 */
79
80/* Constant: assuming 8 bit bytes and 32 bit words */
81#define SHIFT_BIT	(3)
82#define SHIFT_BYTE	(2)
83#define SHIFT_WORD	(SHIFT_BIT+SHIFT_BYTE)
84#define SHIFT_MEGABYTE	(20)
85#define SHIFT_MEGAWORD	(SHIFT_MEGABYTE-SHIFT_BYTE)
86
87/*
88 * Using virtual memory can cause thrashing.  This should be the largest
89 * number that is supported without a large amount of disk activity --
90 * that would increase the run time from hours to days or weeks!
91 */
92#define LARGE_MINIMUM	(8UL)	/* megabytes */
93
94/*
95 * Do not increase this number beyond the unsigned integer bit size.
96 * Due to a multiple of 4, it must be LESS than 128 (yielding 2**30 bits).
97 */
98#define LARGE_MAXIMUM	(127UL)	/* megabytes */
99
100/*
101 * Constant: when used with 32-bit integers, the largest sieve prime
102 * has to be less than 2**32.
103 */
104#define SMALL_MAXIMUM	(0xffffffffUL)
105
106/* Constant: can sieve all primes less than 2**32, as 65537**2 > 2**32-1. */
107#define TINY_NUMBER	(1UL<<16)
108
109/* Ensure enough bit space for testing 2*q. */
110#define TEST_MAXIMUM	(1UL<<16)
111#define TEST_MINIMUM	(QSIZE_MINIMUM + 1)
112/* real TEST_MINIMUM	(1UL << (SHIFT_WORD - TEST_POWER)) */
113#define TEST_POWER	(3)	/* 2**n, n < SHIFT_WORD */
114
115/* bit operations on 32-bit words */
116#define BIT_CLEAR(a,n)	((a)[(n)>>SHIFT_WORD] &= ~(1L << ((n) & 31)))
117#define BIT_SET(a,n)	((a)[(n)>>SHIFT_WORD] |= (1L << ((n) & 31)))
118#define BIT_TEST(a,n)	((a)[(n)>>SHIFT_WORD] & (1L << ((n) & 31)))
119
120/*
121 * Prime testing defines
122 */
123
124/* Minimum number of primality tests to perform */
125#define TRIAL_MINIMUM	(4)
126
127/*
128 * Sieving data (XXX - move to struct)
129 */
130
131/* sieve 2**16 */
132static u_int32_t *TinySieve, tinybits;
133
134/* sieve 2**30 in 2**16 parts */
135static u_int32_t *SmallSieve, smallbits, smallbase;
136
137/* sieve relative to the initial value */
138static u_int32_t *LargeSieve, largewords, largetries, largenumbers;
139static u_int32_t largebits, largememory;	/* megabytes */
140static BIGNUM *largebase;
141
142int gen_candidates(FILE *, u_int32_t, u_int32_t, BIGNUM *);
143int prime_test(FILE *, FILE *, u_int32_t, u_int32_t, char *, unsigned long,
144    unsigned long);
145
146/*
147 * print moduli out in consistent form,
148 */
149static int
150qfileout(FILE * ofile, u_int32_t otype, u_int32_t otests, u_int32_t otries,
151    u_int32_t osize, u_int32_t ogenerator, BIGNUM * omodulus)
152{
153	struct tm *gtm;
154	time_t time_now;
155	int res;
156
157	time(&time_now);
158	gtm = gmtime(&time_now);
159	if (gtm == NULL)
160		return -1;
161
162	res = fprintf(ofile, "%04d%02d%02d%02d%02d%02d %u %u %u %u %x ",
163	    gtm->tm_year + 1900, gtm->tm_mon + 1, gtm->tm_mday,
164	    gtm->tm_hour, gtm->tm_min, gtm->tm_sec,
165	    otype, otests, otries, osize, ogenerator);
166
167	if (res < 0)
168		return (-1);
169
170	if (BN_print_fp(ofile, omodulus) < 1)
171		return (-1);
172
173	res = fprintf(ofile, "\n");
174	fflush(ofile);
175
176	return (res > 0 ? 0 : -1);
177}
178
179
180/*
181 ** Sieve p's and q's with small factors
182 */
183static void
184sieve_large(u_int32_t s32)
185{
186	u_int64_t r, u, s = s32;
187
188	debug3("sieve_large %u", s32);
189	largetries++;
190	/* r = largebase mod s */
191	r = BN_mod_word(largebase, s32);
192	if (r == 0)
193		u = 0; /* s divides into largebase exactly */
194	else
195		u = s - r; /* largebase+u is first entry divisible by s */
196
197	if (u < largebits * 2ULL) {
198		/*
199		 * The sieve omits p's and q's divisible by 2, so ensure that
200		 * largebase+u is odd. Then, step through the sieve in
201		 * increments of 2*s
202		 */
203		if (u & 0x1)
204			u += s; /* Make largebase+u odd, and u even */
205
206		/* Mark all multiples of 2*s */
207		for (u /= 2; u < largebits; u += s)
208			BIT_SET(LargeSieve, u);
209	}
210
211	/* r = p mod s */
212	r = (2 * r + 1) % s;
213	if (r == 0)
214		u = 0; /* s divides p exactly */
215	else
216		u = s - r; /* p+u is first entry divisible by s */
217
218	if (u < largebits * 4ULL) {
219		/*
220		 * The sieve omits p's divisible by 4, so ensure that
221		 * largebase+u is not. Then, step through the sieve in
222		 * increments of 4*s
223		 */
224		while (u & 0x3) {
225			if (SMALL_MAXIMUM - u < s)
226				return;
227			u += s;
228		}
229
230		/* Mark all multiples of 4*s */
231		for (u /= 4; u < largebits; u += s)
232			BIT_SET(LargeSieve, u);
233	}
234}
235
236/*
237 * list candidates for Sophie-Germain primes (where q = (p-1)/2)
238 * to standard output.
239 * The list is checked against small known primes (less than 2**30).
240 */
241int
242gen_candidates(FILE *out, u_int32_t memory, u_int32_t power, BIGNUM *start)
243{
244	BIGNUM *q;
245	u_int32_t j, r, s, t;
246	u_int32_t smallwords = TINY_NUMBER >> 6;
247	u_int32_t tinywords = TINY_NUMBER >> 6;
248	time_t time_start, time_stop;
249	u_int32_t i;
250	int ret = 0;
251
252	largememory = memory;
253
254	if (memory != 0 &&
255	    (memory < LARGE_MINIMUM || memory > LARGE_MAXIMUM)) {
256		error("Invalid memory amount (min %ld, max %ld)",
257		    LARGE_MINIMUM, LARGE_MAXIMUM);
258		return (-1);
259	}
260
261	/*
262	 * Set power to the length in bits of the prime to be generated.
263	 * This is changed to 1 less than the desired safe prime moduli p.
264	 */
265	if (power > TEST_MAXIMUM) {
266		error("Too many bits: %u > %lu", power, TEST_MAXIMUM);
267		return (-1);
268	} else if (power < TEST_MINIMUM) {
269		error("Too few bits: %u < %u", power, TEST_MINIMUM);
270		return (-1);
271	}
272	power--; /* decrement before squaring */
273
274	/*
275	 * The density of ordinary primes is on the order of 1/bits, so the
276	 * density of safe primes should be about (1/bits)**2. Set test range
277	 * to something well above bits**2 to be reasonably sure (but not
278	 * guaranteed) of catching at least one safe prime.
279	 */
280	largewords = ((power * power) >> (SHIFT_WORD - TEST_POWER));
281
282	/*
283	 * Need idea of how much memory is available. We don't have to use all
284	 * of it.
285	 */
286	if (largememory > LARGE_MAXIMUM) {
287		logit("Limited memory: %u MB; limit %lu MB",
288		    largememory, LARGE_MAXIMUM);
289		largememory = LARGE_MAXIMUM;
290	}
291
292	if (largewords <= (largememory << SHIFT_MEGAWORD)) {
293		logit("Increased memory: %u MB; need %u bytes",
294		    largememory, (largewords << SHIFT_BYTE));
295		largewords = (largememory << SHIFT_MEGAWORD);
296	} else if (largememory > 0) {
297		logit("Decreased memory: %u MB; want %u bytes",
298		    largememory, (largewords << SHIFT_BYTE));
299		largewords = (largememory << SHIFT_MEGAWORD);
300	}
301
302	TinySieve = xcalloc(tinywords, sizeof(u_int32_t));
303	tinybits = tinywords << SHIFT_WORD;
304
305	SmallSieve = xcalloc(smallwords, sizeof(u_int32_t));
306	smallbits = smallwords << SHIFT_WORD;
307
308	/*
309	 * dynamically determine available memory
310	 */
311	while ((LargeSieve = calloc(largewords, sizeof(u_int32_t))) == NULL)
312		largewords -= (1L << (SHIFT_MEGAWORD - 2)); /* 1/4 MB chunks */
313
314	largebits = largewords << SHIFT_WORD;
315	largenumbers = largebits * 2;	/* even numbers excluded */
316
317	/* validation check: count the number of primes tried */
318	largetries = 0;
319	if ((q = BN_new()) == NULL)
320		fatal("BN_new failed");
321
322	/*
323	 * Generate random starting point for subprime search, or use
324	 * specified parameter.
325	 */
326	if ((largebase = BN_new()) == NULL)
327		fatal("BN_new failed");
328	if (start == NULL) {
329		if (BN_rand(largebase, power, 1, 1) == 0)
330			fatal("BN_rand failed");
331	} else {
332		if (BN_copy(largebase, start) == NULL)
333			fatal("BN_copy: failed");
334	}
335
336	/* ensure odd */
337	if (BN_set_bit(largebase, 0) == 0)
338		fatal("BN_set_bit: failed");
339
340	time(&time_start);
341
342	logit("%.24s Sieve next %u plus %u-bit", ctime(&time_start),
343	    largenumbers, power);
344	debug2("start point: 0x%s", BN_bn2hex(largebase));
345
346	/*
347	 * TinySieve
348	 */
349	for (i = 0; i < tinybits; i++) {
350		if (BIT_TEST(TinySieve, i))
351			continue; /* 2*i+3 is composite */
352
353		/* The next tiny prime */
354		t = 2 * i + 3;
355
356		/* Mark all multiples of t */
357		for (j = i + t; j < tinybits; j += t)
358			BIT_SET(TinySieve, j);
359
360		sieve_large(t);
361	}
362
363	/*
364	 * Start the small block search at the next possible prime. To avoid
365	 * fencepost errors, the last pass is skipped.
366	 */
367	for (smallbase = TINY_NUMBER + 3;
368	    smallbase < (SMALL_MAXIMUM - TINY_NUMBER);
369	    smallbase += TINY_NUMBER) {
370		for (i = 0; i < tinybits; i++) {
371			if (BIT_TEST(TinySieve, i))
372				continue; /* 2*i+3 is composite */
373
374			/* The next tiny prime */
375			t = 2 * i + 3;
376			r = smallbase % t;
377
378			if (r == 0) {
379				s = 0; /* t divides into smallbase exactly */
380			} else {
381				/* smallbase+s is first entry divisible by t */
382				s = t - r;
383			}
384
385			/*
386			 * The sieve omits even numbers, so ensure that
387			 * smallbase+s is odd. Then, step through the sieve
388			 * in increments of 2*t
389			 */
390			if (s & 1)
391				s += t; /* Make smallbase+s odd, and s even */
392
393			/* Mark all multiples of 2*t */
394			for (s /= 2; s < smallbits; s += t)
395				BIT_SET(SmallSieve, s);
396		}
397
398		/*
399		 * SmallSieve
400		 */
401		for (i = 0; i < smallbits; i++) {
402			if (BIT_TEST(SmallSieve, i))
403				continue; /* 2*i+smallbase is composite */
404
405			/* The next small prime */
406			sieve_large((2 * i) + smallbase);
407		}
408
409		memset(SmallSieve, 0, smallwords << SHIFT_BYTE);
410	}
411
412	time(&time_stop);
413
414	logit("%.24s Sieved with %u small primes in %lld seconds",
415	    ctime(&time_stop), largetries, (long long)(time_stop - time_start));
416
417	for (j = r = 0; j < largebits; j++) {
418		if (BIT_TEST(LargeSieve, j))
419			continue; /* Definitely composite, skip */
420
421		debug2("test q = largebase+%u", 2 * j);
422		if (BN_set_word(q, 2 * j) == 0)
423			fatal("BN_set_word failed");
424		if (BN_add(q, q, largebase) == 0)
425			fatal("BN_add failed");
426		if (qfileout(out, MODULI_TYPE_SOPHIE_GERMAIN,
427		    MODULI_TESTS_SIEVE, largetries,
428		    (power - 1) /* MSB */, (0), q) == -1) {
429			ret = -1;
430			break;
431		}
432
433		r++; /* count q */
434	}
435
436	time(&time_stop);
437
438	free(LargeSieve);
439	free(SmallSieve);
440	free(TinySieve);
441
442	logit("%.24s Found %u candidates", ctime(&time_stop), r);
443
444	return (ret);
445}
446
447static void
448write_checkpoint(char *cpfile, u_int32_t lineno)
449{
450	FILE *fp;
451	char tmp[PATH_MAX];
452	int r, writeok, closeok;
453
454	r = snprintf(tmp, sizeof(tmp), "%s.XXXXXXXXXX", cpfile);
455	if (r < 0 || r >= PATH_MAX) {
456		logit("write_checkpoint: temp pathname too long");
457		return;
458	}
459	if ((r = mkstemp(tmp)) == -1) {
460		logit("mkstemp(%s): %s", tmp, strerror(errno));
461		return;
462	}
463	if ((fp = fdopen(r, "w")) == NULL) {
464		logit("write_checkpoint: fdopen: %s", strerror(errno));
465		unlink(tmp);
466		close(r);
467		return;
468	}
469	writeok = (fprintf(fp, "%lu\n", (unsigned long)lineno) > 0);
470	closeok = (fclose(fp) == 0);
471	if (writeok && closeok && rename(tmp, cpfile) == 0) {
472		debug3("wrote checkpoint line %lu to '%s'",
473		    (unsigned long)lineno, cpfile);
474	} else {
475		logit("failed to write to checkpoint file '%s': %s", cpfile,
476		    strerror(errno));
477		(void)unlink(tmp);
478	}
479}
480
481static unsigned long
482read_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
497static unsigned long
498count_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
514static char *
515fmt_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
530static void
531print_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 */
576int
577prime_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