diff options
Diffstat (limited to 'libtommath/bn_mp_prime_is_prime.c')
-rw-r--r-- | libtommath/bn_mp_prime_is_prime.c | 83 |
1 files changed, 83 insertions, 0 deletions
diff --git a/libtommath/bn_mp_prime_is_prime.c b/libtommath/bn_mp_prime_is_prime.c new file mode 100644 index 0000000..9753094 --- /dev/null +++ b/libtommath/bn_mp_prime_is_prime.c @@ -0,0 +1,83 @@ +#include <tommath.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, tomstdenis@iahu.ca, http://math.libtomcrypt.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 + +/* $Source: /root/tcl/repos-to-convert/tcl/libtommath/bn_mp_prime_is_prime.c,v $ */ +/* $Revision: 1.1.1.1.2.1 $ */ +/* $Date: 2005/09/26 20:16:53 $ */ |