2 * Copyright (c) 1989, 1993
3 * The Regents of the University of California. All rights reserved.
5 * This code is derived from software contributed to Berkeley by
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9 * modification, are permitted provided that the following conditions
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16 * 3. Neither the name of the University nor the names of its contributors
17 * may be used to endorse or promote products derived from this software
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20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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34 #include <sys/cdefs.h>
36 __COPYRIGHT("@(#) Copyright (c) 1989, 1993\
37 The Regents of the University of California. All rights reserved.");
40 __SCCSID("@(#)factor.c 8.4 (Berkeley) 5/4/95");
43 __RCSID("$NetBSD: factor.c,v 1.19 2009/08/12 05:54:31 dholland Exp $");
50 * factor - factor a number into primes
52 * By: Landon Curt Noll chongo@toad.com, ...!{sun,tolsoft}!hoptoad!chongo
54 * chongo <for a good prime call: 391581 * 2^216193 - 1> /\oo/\
57 * factor [-h] [number] ...
59 * The form of the output is:
61 * number: factor1 factor1 factor2 factor3 factor3 factor3 ...
63 * where factor1 <= factor2 <= factor3 <= ...
65 * If no args are given, the list of numbers are read from stdin.
82 #include <openssl/bn.h>
84 #if OPENSSL_VERSION_NUMBER < 0x30000000L
86 BN_check_prime(BIGNUM *p, BN_CTX *ctx, BN_GENCB *cb)
88 const int nchecks = 5;
90 return BN_is_prime_ex(p, nchecks, ctx, cb);
94 static void pollard_pminus1(BIGNUM *); /* print factors for big numbers */
99 typedef u_long BN_ULONG;
102 #define BN_CTX_new() NULL
103 #define BN_new() ((BIGNUM *)calloc(sizeof(BIGNUM), 1))
104 #define BN_is_zero(v) (*(v) == 0)
105 #define BN_is_one(v) (*(v) == 1)
106 #define BN_mod_word(a, b) (*(a) % (b))
108 static int BN_dec2bn(BIGNUM **, const char *);
109 static int BN_hex2bn(BIGNUM **, const char *);
110 static BN_ULONG BN_div_word(BIGNUM *, BN_ULONG);
111 static void BN_print_fp(FILE *, const BIGNUM *);
115 static void BN_print_dec_fp(FILE *, const BIGNUM *);
116 static void convert_str2bn(BIGNUM **, char *);
117 static bool is_hex_str(char *);
118 static void pr_fact(BIGNUM *); /* print factors of a value */
119 static void pr_print(BIGNUM *); /* print a prime */
120 static void usage(void);
122 static BN_CTX *ctx; /* just use a global context */
126 main(int argc, char *argv[])
130 char *p, buf[LINE_MAX]; /* > max number of digits. */
135 errx(1, "can't initialise bignum");
137 while ((ch = getopt(argc, argv, "h")) != -1)
149 /* No args supplied, read numbers from stdin. */
152 if (fgets(buf, sizeof(buf), stdin) == NULL) {
157 for (p = buf; isblank(*p); ++p);
158 if (*p == '\n' || *p == '\0')
160 convert_str2bn(&val, p);
163 /* Factor the arguments. */
165 for (p = *argv; p != NULL; p = *++argv) {
166 convert_str2bn(&val, p);
173 * pr_fact - print the factors of a number
175 * Print the factors of the number, from the lowest to the highest.
176 * A factor will be printed multiple times if it divides the value
179 * Factors are printed with leading tabs.
184 const ubig *fact; /* The factor found. */
186 /* Firewall - catch 0 and 1. */
187 if (BN_is_zero(val)) /* Historical practice; 0 just exits. */
189 if (BN_is_one(val)) {
198 BN_print_fp(stdout, val);
200 BN_print_dec_fp(stdout, val);
202 for (fact = &prime[0]; !BN_is_one(val); ++fact) {
203 /* Look for the smallest factor. */
205 if (BN_mod_word(val, (BN_ULONG)*fact) == 0)
207 } while (++fact <= pr_limit);
209 /* Watch for primes larger than the table. */
210 if (fact > pr_limit) {
215 BN_set_word(bnfact, *(fact - 1));
216 if (!BN_sqr(bnfact, bnfact, ctx))
217 errx(1, "error in BN_sqr()");
218 if (BN_cmp(bnfact, val) > 0 ||
219 BN_check_prime(val, NULL, NULL) == 1)
222 pollard_pminus1(val);
229 /* Divide factor out until none are left. */
231 printf(hflag ? " 0x%" PRIx64 "" : " %" PRIu64 "", *fact);
232 BN_div_word(val, (BN_ULONG)*fact);
233 } while (BN_mod_word(val, (BN_ULONG)*fact) == 0);
235 /* Let the user know we're doing something. */
242 pr_print(BIGNUM *val)
245 fputs(" 0x", stdout);
246 BN_print_fp(stdout, val);
249 BN_print_dec_fp(stdout, val);
256 fprintf(stderr, "usage: factor [-h] [value ...]\n");
262 /* pollard p-1, algorithm from Jim Gillogly, May 2000 */
264 pollard_pminus1(BIGNUM *val)
266 BIGNUM *base, *rbase, *num, *i, *x;
274 BN_set_word(rbase, 1);
276 if (!BN_add_word(rbase, 1))
277 errx(1, "error in BN_add_word()");
279 BN_copy(base, rbase);
282 BN_mod_exp(base, base, i, val, ctx);
288 if (!BN_gcd(x, x, val, ctx))
289 errx(1, "error in BN_gcd()");
292 if (BN_check_prime(x, NULL, NULL) == 1)
298 BN_div(num, NULL, val, x, ctx);
301 if (BN_check_prime(num, NULL, NULL) == 1) {
308 if (!BN_add_word(i, 1))
309 errx(1, "error in BN_add_word()");
314 * Sigh.. No _decimal_ output to file functions in BN.
317 BN_print_dec_fp(FILE *fp, const BIGNUM *num)
321 buf = BN_bn2dec(num);
323 return; /* XXX do anything here? */
324 fprintf(fp, "%s", buf);
331 BN_print_fp(FILE *fp, const BIGNUM *num)
333 fprintf(fp, "%lx", (unsigned long)*num);
337 BN_print_dec_fp(FILE *fp, const BIGNUM *num)
339 fprintf(fp, "%lu", (unsigned long)*num);
343 BN_dec2bn(BIGNUM **a, const char *str)
348 **a = strtoul(str, &p, 10);
349 return (errno == 0 ? 1 : 0); /* OpenSSL returns 0 on error! */
353 BN_hex2bn(BIGNUM **a, const char *str)
358 **a = strtoul(str, &p, 16);
359 return (errno == 0 ? 1 : 0); /* OpenSSL returns 0 on error! */
363 BN_div_word(BIGNUM *a, BN_ULONG b)
375 * Scan the string from left-to-right to see if the longest substring
376 * is a valid hexadecimal number.
379 is_hex_str(char *str)
382 bool saw_hex = false;
384 for (p = str; *p; p++) {
388 if (c >= 'a' && c <= 'f') {
392 break; /* Not a hexadecimal digit. */
397 /* Convert string pointed to by *str to a bignum. */
399 convert_str2bn(BIGNUM **val, char *p)
405 errx(1, "negative numbers aren't permitted.");
408 if (*p == 'x' || *p == 'X')
409 n = BN_hex2bn(val, ++p);
411 n = is_hex_str(p) ? BN_hex2bn(val, p) : BN_dec2bn(val, p);
414 errx(1, "%s: illegal numeric format.", p);