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Annotation of src/usr.bin/ssh/moduli.c, Revision 1.11

1.11    ! avsm        1: /* $OpenBSD: moduli.c,v 1.10 2005/01/17 03:25:46 dtucker Exp $ */
1.1       djm         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: #include "xmalloc.h"
                     42: #include "log.h"
                     43:
                     44: #include <openssl/bn.h>
                     45:
                     46: /*
                     47:  * File output defines
                     48:  */
                     49:
                     50: /* need line long enough for largest moduli plus headers */
1.9       deraadt    51: #define QLINESIZE              (100+8192)
1.1       djm        52:
                     53: /* Type: decimal.
                     54:  * Specifies the internal structure of the prime modulus.
                     55:  */
1.9       deraadt    56: #define QTYPE_UNKNOWN          (0)
                     57: #define QTYPE_UNSTRUCTURED     (1)
                     58: #define QTYPE_SAFE             (2)
1.10      dtucker    59: #define QTYPE_SCHNORR          (3)
1.9       deraadt    60: #define QTYPE_SOPHIE_GERMAIN   (4)
                     61: #define QTYPE_STRONG           (5)
1.1       djm        62:
                     63: /* Tests: decimal (bit field).
                     64:  * Specifies the methods used in checking for primality.
                     65:  * Usually, more than one test is used.
                     66:  */
1.9       deraadt    67: #define QTEST_UNTESTED         (0x00)
                     68: #define QTEST_COMPOSITE                (0x01)
                     69: #define QTEST_SIEVE            (0x02)
                     70: #define QTEST_MILLER_RABIN     (0x04)
                     71: #define QTEST_JACOBI           (0x08)
                     72: #define QTEST_ELLIPTIC         (0x10)
1.1       djm        73:
1.5       djm        74: /*
                     75:  * Size: decimal.
1.1       djm        76:  * Specifies the number of the most significant bit (0 to M).
1.5       djm        77:  * WARNING: internally, usually 1 to N.
1.1       djm        78:  */
1.9       deraadt    79: #define QSIZE_MINIMUM          (511)
1.1       djm        80:
                     81: /*
                     82:  * Prime sieving defines
                     83:  */
                     84:
                     85: /* Constant: assuming 8 bit bytes and 32 bit words */
1.9       deraadt    86: #define SHIFT_BIT      (3)
                     87: #define SHIFT_BYTE     (2)
                     88: #define SHIFT_WORD     (SHIFT_BIT+SHIFT_BYTE)
                     89: #define SHIFT_MEGABYTE (20)
                     90: #define SHIFT_MEGAWORD (SHIFT_MEGABYTE-SHIFT_BYTE)
1.1       djm        91:
                     92: /*
1.7       djm        93:  * Using virtual memory can cause thrashing.  This should be the largest
                     94:  * number that is supported without a large amount of disk activity --
                     95:  * that would increase the run time from hours to days or weeks!
                     96:  */
1.9       deraadt    97: #define LARGE_MINIMUM  (8UL)   /* megabytes */
1.7       djm        98:
                     99: /*
                    100:  * Do not increase this number beyond the unsigned integer bit size.
                    101:  * Due to a multiple of 4, it must be LESS than 128 (yielding 2**30 bits).
                    102:  */
1.9       deraadt   103: #define LARGE_MAXIMUM  (127UL) /* megabytes */
1.7       djm       104:
                    105: /*
1.1       djm       106:  * Constant: when used with 32-bit integers, the largest sieve prime
                    107:  * has to be less than 2**32.
                    108:  */
1.9       deraadt   109: #define SMALL_MAXIMUM  (0xffffffffUL)
1.1       djm       110:
                    111: /* Constant: can sieve all primes less than 2**32, as 65537**2 > 2**32-1. */
1.9       deraadt   112: #define TINY_NUMBER    (1UL<<16)
1.1       djm       113:
                    114: /* Ensure enough bit space for testing 2*q. */
                    115: #define TEST_MAXIMUM    (1UL<<16)
                    116: #define TEST_MINIMUM    (QSIZE_MINIMUM + 1)
                    117: /* real TEST_MINIMUM    (1UL << (SHIFT_WORD - TEST_POWER)) */
                    118: #define TEST_POWER      (3)    /* 2**n, n < SHIFT_WORD */
                    119:
                    120: /* bit operations on 32-bit words */
                    121: #define BIT_CLEAR(a,n)  ((a)[(n)>>SHIFT_WORD] &= ~(1L << ((n) & 31)))
                    122: #define BIT_SET(a,n)    ((a)[(n)>>SHIFT_WORD] |= (1L << ((n) & 31)))
                    123: #define BIT_TEST(a,n)   ((a)[(n)>>SHIFT_WORD] & (1L << ((n) & 31)))
                    124:
                    125: /*
                    126:  * Prime testing defines
                    127:  */
                    128:
1.7       djm       129: /* Minimum number of primality tests to perform */
                    130: #define TRIAL_MINIMUM           (4)
                    131:
1.1       djm       132: /*
                    133:  * Sieving data (XXX - move to struct)
                    134:  */
                    135:
                    136: /* sieve 2**16 */
                    137: static u_int32_t *TinySieve, tinybits;
                    138:
                    139: /* sieve 2**30 in 2**16 parts */
                    140: static u_int32_t *SmallSieve, smallbits, smallbase;
                    141:
                    142: /* sieve relative to the initial value */
                    143: static u_int32_t *LargeSieve, largewords, largetries, largenumbers;
                    144: static u_int32_t largebits, largememory;       /* megabytes */
                    145: static BIGNUM *largebase;
                    146:
1.11    ! avsm      147: int gen_candidates(FILE *, u_int32_t, u_int32_t, BIGNUM *);
1.8       markus    148: int prime_test(FILE *, FILE *, u_int32_t, u_int32_t);
1.1       djm       149:
                    150: /*
                    151:  * print moduli out in consistent form,
                    152:  */
                    153: static int
                    154: qfileout(FILE * ofile, u_int32_t otype, u_int32_t otests, u_int32_t otries,
                    155:     u_int32_t osize, u_int32_t ogenerator, BIGNUM * omodulus)
                    156: {
                    157:        struct tm *gtm;
                    158:        time_t time_now;
                    159:        int res;
                    160:
                    161:        time(&time_now);
                    162:        gtm = gmtime(&time_now);
1.2       djm       163:
1.1       djm       164:        res = fprintf(ofile, "%04d%02d%02d%02d%02d%02d %u %u %u %u %x ",
                    165:            gtm->tm_year + 1900, gtm->tm_mon + 1, gtm->tm_mday,
                    166:            gtm->tm_hour, gtm->tm_min, gtm->tm_sec,
                    167:            otype, otests, otries, osize, ogenerator);
                    168:
                    169:        if (res < 0)
                    170:                return (-1);
                    171:
                    172:        if (BN_print_fp(ofile, omodulus) < 1)
                    173:                return (-1);
                    174:
                    175:        res = fprintf(ofile, "\n");
                    176:        fflush(ofile);
                    177:
                    178:        return (res > 0 ? 0 : -1);
                    179: }
                    180:
                    181:
                    182: /*
                    183:  ** Sieve p's and q's with small factors
                    184:  */
                    185: static void
                    186: sieve_large(u_int32_t s)
                    187: {
                    188:        u_int32_t r, u;
                    189:
1.5       djm       190:        debug3("sieve_large %u", s);
1.1       djm       191:        largetries++;
                    192:        /* r = largebase mod s */
                    193:        r = BN_mod_word(largebase, s);
                    194:        if (r == 0)
                    195:                u = 0; /* s divides into largebase exactly */
                    196:        else
                    197:                u = s - r; /* largebase+u is first entry divisible by s */
                    198:
                    199:        if (u < largebits * 2) {
                    200:                /*
                    201:                 * The sieve omits p's and q's divisible by 2, so ensure that
                    202:                 * largebase+u is odd. Then, step through the sieve in
                    203:                 * increments of 2*s
                    204:                 */
                    205:                if (u & 0x1)
                    206:                        u += s; /* Make largebase+u odd, and u even */
                    207:
                    208:                /* Mark all multiples of 2*s */
                    209:                for (u /= 2; u < largebits; u += s)
                    210:                        BIT_SET(LargeSieve, u);
                    211:        }
                    212:
                    213:        /* r = p mod s */
                    214:        r = (2 * r + 1) % s;
                    215:        if (r == 0)
                    216:                u = 0; /* s divides p exactly */
                    217:        else
                    218:                u = s - r; /* p+u is first entry divisible by s */
                    219:
                    220:        if (u < largebits * 4) {
                    221:                /*
                    222:                 * The sieve omits p's divisible by 4, so ensure that
                    223:                 * largebase+u is not. Then, step through the sieve in
                    224:                 * increments of 4*s
                    225:                 */
                    226:                while (u & 0x3) {
                    227:                        if (SMALL_MAXIMUM - u < s)
                    228:                                return;
                    229:                        u += s;
                    230:                }
                    231:
                    232:                /* Mark all multiples of 4*s */
                    233:                for (u /= 4; u < largebits; u += s)
                    234:                        BIT_SET(LargeSieve, u);
                    235:        }
                    236: }
                    237:
                    238: /*
1.6       djm       239:  * list candidates for Sophie-Germain primes (where q = (p-1)/2)
1.1       djm       240:  * to standard output.
                    241:  * The list is checked against small known primes (less than 2**30).
                    242:  */
                    243: int
1.11    ! avsm      244: gen_candidates(FILE *out, u_int32_t memory, u_int32_t power, BIGNUM *start)
1.1       djm       245: {
                    246:        BIGNUM *q;
                    247:        u_int32_t j, r, s, t;
                    248:        u_int32_t smallwords = TINY_NUMBER >> 6;
                    249:        u_int32_t tinywords = TINY_NUMBER >> 6;
                    250:        time_t time_start, time_stop;
1.11    ! avsm      251:        u_int32_t i;
        !           252:        int ret = 0;
1.1       djm       253:
                    254:        largememory = memory;
                    255:
1.7       djm       256:        if (memory != 0 &&
                    257:           (memory < LARGE_MINIMUM || memory > LARGE_MAXIMUM)) {
                    258:                error("Invalid memory amount (min %ld, max %ld)",
                    259:                    LARGE_MINIMUM, LARGE_MAXIMUM);
                    260:                return (-1);
                    261:        }
                    262:
1.1       djm       263:        /*
1.2       djm       264:         * Set power to the length in bits of the prime to be generated.
                    265:         * This is changed to 1 less than the desired safe prime moduli p.
                    266:         */
1.1       djm       267:        if (power > TEST_MAXIMUM) {
                    268:                error("Too many bits: %u > %lu", power, TEST_MAXIMUM);
                    269:                return (-1);
                    270:        } else if (power < TEST_MINIMUM) {
                    271:                error("Too few bits: %u < %u", power, TEST_MINIMUM);
                    272:                return (-1);
                    273:        }
                    274:        power--; /* decrement before squaring */
                    275:
                    276:        /*
1.2       djm       277:         * The density of ordinary primes is on the order of 1/bits, so the
                    278:         * density of safe primes should be about (1/bits)**2. Set test range
                    279:         * to something well above bits**2 to be reasonably sure (but not
                    280:         * guaranteed) of catching at least one safe prime.
1.1       djm       281:         */
                    282:        largewords = ((power * power) >> (SHIFT_WORD - TEST_POWER));
                    283:
                    284:        /*
1.2       djm       285:         * Need idea of how much memory is available. We don't have to use all
                    286:         * of it.
1.1       djm       287:         */
                    288:        if (largememory > LARGE_MAXIMUM) {
                    289:                logit("Limited memory: %u MB; limit %lu MB",
                    290:                    largememory, LARGE_MAXIMUM);
                    291:                largememory = LARGE_MAXIMUM;
                    292:        }
                    293:
                    294:        if (largewords <= (largememory << SHIFT_MEGAWORD)) {
                    295:                logit("Increased memory: %u MB; need %u bytes",
                    296:                    largememory, (largewords << SHIFT_BYTE));
                    297:                largewords = (largememory << SHIFT_MEGAWORD);
                    298:        } else if (largememory > 0) {
                    299:                logit("Decreased memory: %u MB; want %u bytes",
                    300:                    largememory, (largewords << SHIFT_BYTE));
                    301:                largewords = (largememory << SHIFT_MEGAWORD);
                    302:        }
                    303:
                    304:        TinySieve = calloc(tinywords, sizeof(u_int32_t));
                    305:        if (TinySieve == NULL) {
                    306:                error("Insufficient memory for tiny sieve: need %u bytes",
                    307:                    tinywords << SHIFT_BYTE);
                    308:                exit(1);
                    309:        }
                    310:        tinybits = tinywords << SHIFT_WORD;
                    311:
                    312:        SmallSieve = calloc(smallwords, sizeof(u_int32_t));
                    313:        if (SmallSieve == NULL) {
                    314:                error("Insufficient memory for small sieve: need %u bytes",
                    315:                    smallwords << SHIFT_BYTE);
                    316:                xfree(TinySieve);
                    317:                exit(1);
                    318:        }
                    319:        smallbits = smallwords << SHIFT_WORD;
                    320:
                    321:        /*
                    322:         * dynamically determine available memory
                    323:         */
                    324:        while ((LargeSieve = calloc(largewords, sizeof(u_int32_t))) == NULL)
                    325:                largewords -= (1L << (SHIFT_MEGAWORD - 2)); /* 1/4 MB chunks */
                    326:
                    327:        largebits = largewords << SHIFT_WORD;
                    328:        largenumbers = largebits * 2;   /* even numbers excluded */
                    329:
                    330:        /* validation check: count the number of primes tried */
                    331:        largetries = 0;
                    332:        q = BN_new();
                    333:
                    334:        /*
1.2       djm       335:         * Generate random starting point for subprime search, or use
                    336:         * specified parameter.
1.1       djm       337:         */
                    338:        largebase = BN_new();
                    339:        if (start == NULL)
                    340:                BN_rand(largebase, power, 1, 1);
                    341:        else
                    342:                BN_copy(largebase, start);
                    343:
                    344:        /* ensure odd */
                    345:        BN_set_bit(largebase, 0);
                    346:
                    347:        time(&time_start);
                    348:
1.2       djm       349:        logit("%.24s Sieve next %u plus %u-bit", ctime(&time_start),
1.1       djm       350:            largenumbers, power);
                    351:        debug2("start point: 0x%s", BN_bn2hex(largebase));
                    352:
                    353:        /*
1.2       djm       354:         * TinySieve
                    355:         */
1.1       djm       356:        for (i = 0; i < tinybits; i++) {
                    357:                if (BIT_TEST(TinySieve, i))
                    358:                        continue; /* 2*i+3 is composite */
                    359:
                    360:                /* The next tiny prime */
                    361:                t = 2 * i + 3;
                    362:
                    363:                /* Mark all multiples of t */
                    364:                for (j = i + t; j < tinybits; j += t)
                    365:                        BIT_SET(TinySieve, j);
                    366:
                    367:                sieve_large(t);
                    368:        }
                    369:
                    370:        /*
1.2       djm       371:         * Start the small block search at the next possible prime. To avoid
                    372:         * fencepost errors, the last pass is skipped.
                    373:         */
1.1       djm       374:        for (smallbase = TINY_NUMBER + 3;
                    375:             smallbase < (SMALL_MAXIMUM - TINY_NUMBER);
                    376:             smallbase += TINY_NUMBER) {
                    377:                for (i = 0; i < tinybits; i++) {
                    378:                        if (BIT_TEST(TinySieve, i))
                    379:                                continue; /* 2*i+3 is composite */
                    380:
                    381:                        /* The next tiny prime */
                    382:                        t = 2 * i + 3;
                    383:                        r = smallbase % t;
                    384:
                    385:                        if (r == 0) {
                    386:                                s = 0; /* t divides into smallbase exactly */
                    387:                        } else {
                    388:                                /* smallbase+s is first entry divisible by t */
                    389:                                s = t - r;
                    390:                        }
                    391:
                    392:                        /*
                    393:                         * The sieve omits even numbers, so ensure that
                    394:                         * smallbase+s is odd. Then, step through the sieve
                    395:                         * in increments of 2*t
                    396:                         */
                    397:                        if (s & 1)
                    398:                                s += t; /* Make smallbase+s odd, and s even */
                    399:
                    400:                        /* Mark all multiples of 2*t */
                    401:                        for (s /= 2; s < smallbits; s += t)
                    402:                                BIT_SET(SmallSieve, s);
                    403:                }
                    404:
                    405:                /*
1.2       djm       406:                 * SmallSieve
                    407:                 */
1.1       djm       408:                for (i = 0; i < smallbits; i++) {
                    409:                        if (BIT_TEST(SmallSieve, i))
                    410:                                continue; /* 2*i+smallbase is composite */
                    411:
                    412:                        /* The next small prime */
                    413:                        sieve_large((2 * i) + smallbase);
                    414:                }
                    415:
                    416:                memset(SmallSieve, 0, smallwords << SHIFT_BYTE);
                    417:        }
                    418:
                    419:        time(&time_stop);
                    420:
                    421:        logit("%.24s Sieved with %u small primes in %ld seconds",
                    422:            ctime(&time_stop), largetries, (long) (time_stop - time_start));
                    423:
                    424:        for (j = r = 0; j < largebits; j++) {
                    425:                if (BIT_TEST(LargeSieve, j))
                    426:                        continue; /* Definitely composite, skip */
                    427:
                    428:                debug2("test q = largebase+%u", 2 * j);
                    429:                BN_set_word(q, 2 * j);
                    430:                BN_add(q, q, largebase);
1.6       djm       431:                if (qfileout(out, QTYPE_SOPHIE_GERMAIN, QTEST_SIEVE,
1.1       djm       432:                    largetries, (power - 1) /* MSB */, (0), q) == -1) {
                    433:                        ret = -1;
                    434:                        break;
                    435:                }
                    436:
                    437:                r++; /* count q */
                    438:        }
                    439:
                    440:        time(&time_stop);
                    441:
                    442:        xfree(LargeSieve);
                    443:        xfree(SmallSieve);
                    444:        xfree(TinySieve);
                    445:
                    446:        logit("%.24s Found %u candidates", ctime(&time_stop), r);
                    447:
                    448:        return (ret);
                    449: }
                    450:
                    451: /*
                    452:  * perform a Miller-Rabin primality test
                    453:  * on the list of candidates
                    454:  * (checking both q and p)
                    455:  * The result is a list of so-call "safe" primes
                    456:  */
                    457: int
1.7       djm       458: prime_test(FILE *in, FILE *out, u_int32_t trials, u_int32_t generator_wanted)
1.1       djm       459: {
                    460:        BIGNUM *q, *p, *a;
                    461:        BN_CTX *ctx;
                    462:        char *cp, *lp;
                    463:        u_int32_t count_in = 0, count_out = 0, count_possible = 0;
                    464:        u_int32_t generator_known, in_tests, in_tries, in_type, in_size;
                    465:        time_t time_start, time_stop;
                    466:        int res;
1.7       djm       467:
                    468:        if (trials < TRIAL_MINIMUM) {
                    469:                error("Minimum primality trials is %d", TRIAL_MINIMUM);
                    470:                return (-1);
                    471:        }
1.1       djm       472:
                    473:        time(&time_start);
                    474:
                    475:        p = BN_new();
                    476:        q = BN_new();
                    477:        ctx = BN_CTX_new();
                    478:
                    479:        debug2("%.24s Final %u Miller-Rabin trials (%x generator)",
                    480:            ctime(&time_start), trials, generator_wanted);
                    481:
                    482:        res = 0;
                    483:        lp = xmalloc(QLINESIZE + 1);
                    484:        while (fgets(lp, QLINESIZE, in) != NULL) {
                    485:                int ll = strlen(lp);
                    486:
                    487:                count_in++;
                    488:                if (ll < 14 || *lp == '!' || *lp == '#') {
                    489:                        debug2("%10u: comment or short line", count_in);
                    490:                        continue;
                    491:                }
                    492:
                    493:                /* XXX - fragile parser */
                    494:                /* time */
                    495:                cp = &lp[14];   /* (skip) */
                    496:
                    497:                /* type */
                    498:                in_type = strtoul(cp, &cp, 10);
                    499:
                    500:                /* tests */
                    501:                in_tests = strtoul(cp, &cp, 10);
                    502:
                    503:                if (in_tests & QTEST_COMPOSITE) {
                    504:                        debug2("%10u: known composite", count_in);
                    505:                        continue;
                    506:                }
1.5       djm       507:
1.1       djm       508:                /* tries */
                    509:                in_tries = strtoul(cp, &cp, 10);
                    510:
                    511:                /* size (most significant bit) */
                    512:                in_size = strtoul(cp, &cp, 10);
                    513:
                    514:                /* generator (hex) */
                    515:                generator_known = strtoul(cp, &cp, 16);
                    516:
                    517:                /* Skip white space */
                    518:                cp += strspn(cp, " ");
                    519:
                    520:                /* modulus (hex) */
                    521:                switch (in_type) {
1.6       djm       522:                case QTYPE_SOPHIE_GERMAIN:
                    523:                        debug2("%10u: (%u) Sophie-Germain", count_in, in_type);
1.1       djm       524:                        a = q;
                    525:                        BN_hex2bn(&a, cp);
                    526:                        /* p = 2*q + 1 */
                    527:                        BN_lshift(p, q, 1);
                    528:                        BN_add_word(p, 1);
                    529:                        in_size += 1;
                    530:                        generator_known = 0;
                    531:                        break;
1.5       djm       532:                case QTYPE_UNSTRUCTURED:
                    533:                case QTYPE_SAFE:
1.10      dtucker   534:                case QTYPE_SCHNORR:
1.5       djm       535:                case QTYPE_STRONG:
                    536:                case QTYPE_UNKNOWN:
1.1       djm       537:                        debug2("%10u: (%u)", count_in, in_type);
                    538:                        a = p;
                    539:                        BN_hex2bn(&a, cp);
                    540:                        /* q = (p-1) / 2 */
                    541:                        BN_rshift(q, p, 1);
                    542:                        break;
1.5       djm       543:                default:
                    544:                        debug2("Unknown prime type");
                    545:                        break;
1.1       djm       546:                }
                    547:
                    548:                /*
                    549:                 * due to earlier inconsistencies in interpretation, check
                    550:                 * the proposed bit size.
                    551:                 */
1.11    ! avsm      552:                if ((u_int32_t)BN_num_bits(p) != (in_size + 1)) {
1.1       djm       553:                        debug2("%10u: bit size %u mismatch", count_in, in_size);
                    554:                        continue;
                    555:                }
                    556:                if (in_size < QSIZE_MINIMUM) {
                    557:                        debug2("%10u: bit size %u too short", count_in, in_size);
                    558:                        continue;
                    559:                }
                    560:
                    561:                if (in_tests & QTEST_MILLER_RABIN)
                    562:                        in_tries += trials;
                    563:                else
                    564:                        in_tries = trials;
1.5       djm       565:
1.1       djm       566:                /*
                    567:                 * guess unknown generator
                    568:                 */
                    569:                if (generator_known == 0) {
                    570:                        if (BN_mod_word(p, 24) == 11)
                    571:                                generator_known = 2;
                    572:                        else if (BN_mod_word(p, 12) == 5)
                    573:                                generator_known = 3;
                    574:                        else {
                    575:                                u_int32_t r = BN_mod_word(p, 10);
                    576:
1.5       djm       577:                                if (r == 3 || r == 7)
1.1       djm       578:                                        generator_known = 5;
                    579:                        }
                    580:                }
                    581:                /*
                    582:                 * skip tests when desired generator doesn't match
                    583:                 */
                    584:                if (generator_wanted > 0 &&
                    585:                    generator_wanted != generator_known) {
                    586:                        debug2("%10u: generator %d != %d",
                    587:                            count_in, generator_known, generator_wanted);
1.4       dtucker   588:                        continue;
                    589:                }
                    590:
                    591:                /*
                    592:                 * Primes with no known generator are useless for DH, so
                    593:                 * skip those.
                    594:                 */
                    595:                if (generator_known == 0) {
                    596:                        debug2("%10u: no known generator", count_in);
1.1       djm       597:                        continue;
                    598:                }
                    599:
                    600:                count_possible++;
                    601:
                    602:                /*
1.2       djm       603:                 * The (1/4)^N performance bound on Miller-Rabin is
                    604:                 * extremely pessimistic, so don't spend a lot of time
                    605:                 * really verifying that q is prime until after we know
                    606:                 * that p is also prime. A single pass will weed out the
1.1       djm       607:                 * vast majority of composite q's.
                    608:                 */
                    609:                if (BN_is_prime(q, 1, NULL, ctx, NULL) <= 0) {
1.5       djm       610:                        debug("%10u: q failed first possible prime test",
1.1       djm       611:                            count_in);
                    612:                        continue;
                    613:                }
1.2       djm       614:
1.1       djm       615:                /*
1.2       djm       616:                 * q is possibly prime, so go ahead and really make sure
                    617:                 * that p is prime. If it is, then we can go back and do
                    618:                 * the same for q. If p is composite, chances are that
1.1       djm       619:                 * will show up on the first Rabin-Miller iteration so it
                    620:                 * doesn't hurt to specify a high iteration count.
                    621:                 */
                    622:                if (!BN_is_prime(p, trials, NULL, ctx, NULL)) {
1.5       djm       623:                        debug("%10u: p is not prime", count_in);
1.1       djm       624:                        continue;
                    625:                }
                    626:                debug("%10u: p is almost certainly prime", count_in);
                    627:
                    628:                /* recheck q more rigorously */
                    629:                if (!BN_is_prime(q, trials - 1, NULL, ctx, NULL)) {
                    630:                        debug("%10u: q is not prime", count_in);
                    631:                        continue;
                    632:                }
                    633:                debug("%10u: q is almost certainly prime", count_in);
                    634:
1.2       djm       635:                if (qfileout(out, QTYPE_SAFE, (in_tests | QTEST_MILLER_RABIN),
1.1       djm       636:                    in_tries, in_size, generator_known, p)) {
                    637:                        res = -1;
                    638:                        break;
                    639:                }
                    640:
                    641:                count_out++;
                    642:        }
                    643:
                    644:        time(&time_stop);
                    645:        xfree(lp);
                    646:        BN_free(p);
                    647:        BN_free(q);
                    648:        BN_CTX_free(ctx);
                    649:
                    650:        logit("%.24s Found %u safe primes of %u candidates in %ld seconds",
1.2       djm       651:            ctime(&time_stop), count_out, count_possible,
1.1       djm       652:            (long) (time_stop - time_start));
                    653:
                    654:        return (res);
                    655: }