Mercurial > dropbear
view libtommath/bn_mp_prime_is_prime.c @ 1646:6d1bbe7d5fa5 DROPBEAR_2019.77
2019.77
author | Matt Johnston <matt@ucc.asn.au> |
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date | Sat, 23 Mar 2019 21:46:29 +0800 |
parents | 8bba51a55704 |
children | f52919ffd3b1 |
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#include <tommath_private.h> #ifdef BN_MP_PRIME_IS_PRIME_C /* LibTomMath, multiple-precision integer library -- Tom St Denis * * LibTomMath is a library that provides multiple-precision * integer arithmetic as well as number theoretic functionality. * * The library was designed directly after the MPI library by * Michael Fromberger but has been written from scratch with * additional optimizations in place. * * The library is free for all purposes without any express * guarantee it works. * * Tom St Denis, [email protected], http://libtom.org */ /* performs a variable number of rounds of Miller-Rabin * * Probability of error after t rounds is no more than * * Sets result to 1 if probably prime, 0 otherwise */ int mp_prime_is_prime (mp_int * a, int t, int *result) { mp_int b; int ix, err, res; /* default to no */ *result = MP_NO; /* valid value of t? */ if ((t <= 0) || (t > PRIME_SIZE)) { return MP_VAL; } /* is the input equal to one of the primes in the table? */ for (ix = 0; ix < PRIME_SIZE; ix++) { if (mp_cmp_d(a, ltm_prime_tab[ix]) == MP_EQ) { *result = 1; return MP_OKAY; } } /* first perform trial division */ if ((err = mp_prime_is_divisible (a, &res)) != MP_OKAY) { return err; } /* return if it was trivially divisible */ if (res == MP_YES) { return MP_OKAY; } /* now perform the miller-rabin rounds */ if ((err = mp_init (&b)) != MP_OKAY) { return err; } for (ix = 0; ix < t; ix++) { /* set the prime */ mp_set (&b, ltm_prime_tab[ix]); if ((err = mp_prime_miller_rabin (a, &b, &res)) != MP_OKAY) { goto LBL_B; } if (res == MP_NO) { goto LBL_B; } } /* passed the test */ *result = MP_YES; LBL_B:mp_clear (&b); return err; } #endif /* ref: $Format:%D$ */ /* git commit: $Format:%H$ */ /* commit time: $Format:%ai$ */