2 * SPDX-License-Identifier: BSD-2-Clause
4 * Copyright (c) 2001 Dima Dorfman.
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8 * modification, are permitted provided that the following conditions
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30 * This is the traditional Berkeley MP library implemented in terms of
31 * the OpenSSL BIGNUM library. It was written to replace libgmp, and
32 * is meant to be as compatible with the latter as feasible.
34 * There seems to be a lack of documentation for the Berkeley MP
35 * interface. All I could find was libgmp documentation (which didn't
36 * talk about the semantics of the functions) and an old SunOS 4.1
37 * manual page from 1989. The latter wasn't very detailed, either,
38 * but at least described what the function's arguments were. In
39 * general the interface seems to be archaic, somewhat poorly
40 * designed, and poorly, if at all, documented. It is considered
43 * Miscellaneous notes on this implementation:
45 * - The SunOS manual page mentioned above indicates that if an error
46 * occurs, the library should "produce messages and core images."
47 * Given that most of the functions don't have return values (and
48 * thus no sane way of alerting the caller to an error), this seems
49 * reasonable. The MPERR and MPERRX macros call warn and warnx,
50 * respectively, then abort().
52 * - All the functions which take an argument to be "filled in"
53 * assume that the argument has been initialized by one of the *tom()
54 * routines before being passed to it. I never saw this documented
55 * anywhere, but this seems to be consistent with the way this
58 * - msqrt() is the only routine which had to be implemented which
59 * doesn't have a close counterpart in the OpenSSL BIGNUM library.
60 * It was implemented by hand using Newton's recursive formula.
61 * Doing it this way, although more error-prone, has the positive
62 * sideaffect of testing a lot of other functions; if msqrt()
63 * produces the correct results, most of the other routines will as
66 * - Internal-use-only routines (i.e., those defined here statically
67 * and not in mp.h) have an underscore prepended to their name (this
68 * is more for aesthetical reasons than technical). All such
69 * routines take an extra argument, 'msg', that denotes what they
70 * should call themselves in an error message. This is so a user
71 * doesn't get an error message from a function they didn't call.
74 #include <sys/cdefs.h>
82 #include <openssl/crypto.h>
83 #include <openssl/err.h>
87 #define MPERR(s) do { warn s; abort(); } while (0)
88 #define MPERRX(s) do { warnx s; abort(); } while (0)
89 #define BN_ERRCHECK(msg, expr) do { \
90 if (!(expr)) _bnerr(msg); \
93 static void _bnerr(const char *);
94 static MINT *_dtom(const char *, const char *);
95 static MINT *_itom(const char *, short);
96 static void _madd(const char *, const MINT *, const MINT *, MINT *);
97 static int _mcmpa(const char *, const MINT *, const MINT *);
98 static void _mdiv(const char *, const MINT *, const MINT *, MINT *, MINT *,
100 static void _mfree(const char *, MINT *);
101 static void _moveb(const char *, const BIGNUM *, MINT *);
102 static void _movem(const char *, const MINT *, MINT *);
103 static void _msub(const char *, const MINT *, const MINT *, MINT *);
104 static char *_mtod(const char *, const MINT *);
105 static char *_mtox(const char *, const MINT *);
106 static void _mult(const char *, const MINT *, const MINT *, MINT *, BN_CTX *);
107 static void _sdiv(const char *, const MINT *, short, MINT *, short *, BN_CTX *);
108 static MINT *_xtom(const char *, const char *);
111 * Report an error from one of the BN_* functions using MPERRX.
114 _bnerr(const char *msg)
117 ERR_load_crypto_strings();
118 MPERRX(("%s: %s", msg, ERR_reason_error_string(ERR_get_error())));
122 * Convert a decimal string to an MINT.
125 _dtom(const char *msg, const char *s)
129 mp = malloc(sizeof(*mp));
135 BN_ERRCHECK(msg, BN_dec2bn(&mp->bn, s));
140 * Compute the greatest common divisor of mp1 and mp2; result goes in rmp.
143 mp_gcd(const MINT *mp1, const MINT *mp2, MINT *rmp)
152 if (c == NULL || b == NULL)
154 BN_ERRCHECK("gcd", BN_gcd(b, mp1->bn, mp2->bn, c));
155 _moveb("gcd", b, rmp);
161 * Make an MINT out of a short integer. Return value must be mfree()'d.
164 _itom(const char *msg, short n)
169 asprintf(&s, "%x", n);
181 return (_itom("itom", n));
185 * Compute rmp=mp1+mp2.
188 _madd(const char *msg, const MINT *mp1, const MINT *mp2, MINT *rmp)
195 BN_ERRCHECK(msg, BN_add(b, mp1->bn, mp2->bn));
201 mp_madd(const MINT *mp1, const MINT *mp2, MINT *rmp)
204 _madd("madd", mp1, mp2, rmp);
208 * Return -1, 0, or 1 if mp1<mp2, mp1==mp2, or mp1>mp2, respectivley.
211 mp_mcmp(const MINT *mp1, const MINT *mp2)
214 return (BN_cmp(mp1->bn, mp2->bn));
218 * Same as mcmp but compares absolute values.
221 _mcmpa(const char *msg __unused, const MINT *mp1, const MINT *mp2)
224 return (BN_ucmp(mp1->bn, mp2->bn));
228 * Compute qmp=nmp/dmp and rmp=nmp%dmp.
231 _mdiv(const char *msg, const MINT *nmp, const MINT *dmp, MINT *qmp, MINT *rmp,
240 if (r == NULL || q == NULL)
242 BN_ERRCHECK(msg, BN_div(q, r, nmp->bn, dmp->bn, c));
250 mp_mdiv(const MINT *nmp, const MINT *dmp, MINT *qmp, MINT *rmp)
257 _mdiv("mdiv", nmp, dmp, qmp, rmp, c);
262 * Free memory associated with an MINT.
265 _mfree(const char *msg __unused, MINT *mp)
281 * Read an integer from standard input and stick the result in mp.
282 * The input is treated to be in base 10. This must be the silliest
283 * API in existence; why can't the program read in a string and call
284 * xtom()? (Or if base 10 is desires, perhaps dtom() could be
294 line = fgetln(stdin, &linelen);
297 nline = malloc(linelen + 1);
300 memcpy(nline, line, linelen);
301 nline[linelen] = '\0';
302 rmp = _dtom("min", nline);
303 _movem("min", rmp, mp);
309 * Print the value of mp to standard output in base 10. See blurb
310 * above min() for why this is so useless.
313 mp_mout(const MINT *mp)
317 s = _mtod("mout", mp);
323 * Set the value of tmp to the value of smp (i.e., tmp=smp).
326 mp_move(const MINT *smp, MINT *tmp)
329 _movem("move", smp, tmp);
334 * Internal routine to set the value of tmp to that of sbp.
337 _moveb(const char *msg, const BIGNUM *sbp, MINT *tmp)
340 BN_ERRCHECK(msg, BN_copy(tmp->bn, sbp));
344 * Internal routine to set the value of tmp to that of smp.
347 _movem(const char *msg, const MINT *smp, MINT *tmp)
350 BN_ERRCHECK(msg, BN_copy(tmp->bn, smp->bn));
354 * Compute the square root of nmp and put the result in xmp. The
355 * remainder goes in rmp. Should satisfy: rmp=nmp-(xmp*xmp).
357 * Note that the OpenSSL BIGNUM library does not have a square root
358 * function, so this had to be implemented by hand using Newton's
361 * x = (x + (n / x)) / 2
363 * where x is the square root of the positive number n. In the
364 * beginning, x should be a reasonable guess, but the value 1,
365 * although suboptimal, works, too; this is that is used below.
368 mp_msqrt(const MINT *nmp, MINT *xmp, MINT *rmp)
379 tolerance = _itom("msqrt", 1);
380 x = _itom("msqrt", 1);
381 ox = _itom("msqrt", 0);
382 z1 = _itom("msqrt", 0);
383 z2 = _itom("msqrt", 0);
384 z3 = _itom("msqrt", 0);
386 _movem("msqrt", x, ox);
387 _mdiv("msqrt", nmp, x, z1, z2, c);
388 _madd("msqrt", x, z1, z2);
389 _sdiv("msqrt", z2, 2, x, &i, c);
390 _msub("msqrt", ox, x, z3);
391 } while (_mcmpa("msqrt", z3, tolerance) == 1);
392 _movem("msqrt", x, xmp);
393 _mult("msqrt", x, x, z1, c);
394 _msub("msqrt", nmp, z1, z2);
395 _movem("msqrt", z2, rmp);
396 _mfree("msqrt", tolerance);
406 * Compute rmp=mp1-mp2.
409 _msub(const char *msg, const MINT *mp1, const MINT *mp2, MINT *rmp)
416 BN_ERRCHECK(msg, BN_sub(b, mp1->bn, mp2->bn));
422 mp_msub(const MINT *mp1, const MINT *mp2, MINT *rmp)
425 _msub("msub", mp1, mp2, rmp);
429 * Return a decimal representation of mp. Return value must be
433 _mtod(const char *msg, const MINT *mp)
437 s = BN_bn2dec(mp->bn);
440 asprintf(&s2, "%s", s);
448 * Return a hexadecimal representation of mp. Return value must be
452 _mtox(const char *msg, const MINT *mp)
457 s = BN_bn2hex(mp->bn);
460 asprintf(&s2, "%s", s);
466 * This is a kludge for libgmp compatibility. The latter's
467 * implementation of this function returns lower-case letters,
468 * but BN_bn2hex returns upper-case. Some programs (e.g.,
469 * newkey(1)) are sensitive to this. Although it's probably
470 * their fault, it's nice to be compatible.
473 for (p = s2; p < s2 + len; p++)
480 mp_mtox(const MINT *mp)
483 return (_mtox("mtox", mp));
487 * Compute rmp=mp1*mp2.
490 _mult(const char *msg, const MINT *mp1, const MINT *mp2, MINT *rmp, BN_CTX *c)
497 BN_ERRCHECK(msg, BN_mul(b, mp1->bn, mp2->bn, c));
503 mp_mult(const MINT *mp1, const MINT *mp2, MINT *rmp)
510 _mult("mult", mp1, mp2, rmp, c);
515 * Compute rmp=(bmp^emp)mod mmp. (Note that here and above rpow() '^'
516 * means 'raise to power', not 'bitwise XOR'.)
519 mp_pow(const MINT *bmp, const MINT *emp, const MINT *mmp, MINT *rmp)
528 if (c == NULL || b == NULL)
530 BN_ERRCHECK("pow", BN_mod_exp(b, bmp->bn, emp->bn, mmp->bn, c));
531 _moveb("pow", b, rmp);
537 * Compute rmp=bmp^e. (See note above pow().)
540 mp_rpow(const MINT *bmp, short e, MINT *rmp)
550 if (c == NULL || b == NULL)
552 emp = _itom("rpow", e);
553 BN_ERRCHECK("rpow", BN_exp(b, bmp->bn, emp->bn, c));
554 _moveb("rpow", b, rmp);
561 * Compute qmp=nmp/d and ro=nmp%d.
564 _sdiv(const char *msg, const MINT *nmp, short d, MINT *qmp, short *ro,
575 if (q == NULL || r == NULL)
579 BN_ERRCHECK(msg, BN_div(q, r, nmp->bn, dmp->bn, c));
584 *ro = strtol(s, NULL, 16);
586 MPERR(("%s underflow or overflow", msg));
595 mp_sdiv(const MINT *nmp, short d, MINT *qmp, short *ro)
602 _sdiv("sdiv", nmp, d, qmp, ro, c);
607 * Convert a hexadecimal string to an MINT.
610 _xtom(const char *msg, const char *s)
614 mp = malloc(sizeof(*mp));
620 BN_ERRCHECK(msg, BN_hex2bn(&mp->bn, s));
625 mp_xtom(const char *s)
628 return (_xtom("xtom", s));