BOOLEAN prime_p(unsigned long int number) {
int witnesses[] = { 2, 3, 5, 7, 11, 13, 17, 19 };
/* If number is odd and not equal to 1, perform Rabin-Miller test */
if ((number & 1) && (number ^ 1)) {
int witness;
/* Try with witnesses 2 through min(9, number) */
for (witness = 0; witness < 8 && witnesses[witness] < number; witness++) {
/* If Rabin-Miller fails on this witness, the number is not prime */
if (!rabin_miller(number, witnesses[witness])) {
return FALSE;
}
}
/* If Rabin-Miller didn't fail on any of the witnesses, assume it is prime */
return TRUE;
} else {
/* If number is not odd or is 1, it is only prime if it is 2 */
return (number == 2);
}
}
void gen_prime(unsigned int b_size, mpz_t res) {
gmp_randstate_t state;
struct timeval r_time;
gettimeofday(&r_time,NULL);
gmp_randinit_default(state);
gmp_randseed_ui(state,(r_time.tv_sec * 1000) + (r_time.tv_usec / 1000));
do {
mpz_urandomb(res,state,b_size);
mpz_setbit(res,0);
mpz_setbit(res,b_size - 1);
mpz_setbit(res,b_size - 2);
} while(rabin_miller(res,20,state) == 0);
gmp_randclear(state);
}
