/* Test whether z is likely to be prime:
MP_TRUE means it is probably prime
MP_FALSE means it is definitely composite
*/
mp_result mp_int_is_prime(mp_int z)
{
int i, rem;
mp_result res;
/* First check for divisibility by small primes; this eliminates a
large number of composite candidates quickly
*/
for(i = 0; i < s_ptab_size; ++i) {
if((res = mp_int_div_value(z, s_ptab[i], NULL, &rem)) != MP_OK)
return res;
if(rem == 0)
return MP_FALSE;
}
/* Now try Fermat's test for several prime witnesses (since we now
know from the above that z is not a multiple of any of them)
*/
{
mpz_t tmp;
if((res = mp_int_init(&tmp)) != MP_OK) return res;
for(i = 0; i < 10 && i < s_ptab_size; ++i) {
if((res = mp_int_exptmod_bvalue(s_ptab[i], z, z, &tmp)) != MP_OK)
return res;
if(mp_int_compare_value(&tmp, s_ptab[i]) != 0) {
mp_int_clear(&tmp);
return MP_FALSE;
}
}
mp_int_clear(&tmp);
}
return MP_TRUE;
}
int test_exptmod_bv(testspec_t *t, FILE *ofp)
{
mp_int in[4], out[1];
mp_result res, expect;
int v;
if(!parse_int_values(t, in, out, &expect))
return imath_errno = MP_BADARG, 0;
if((res = mp_int_to_int(in[0], &v)) != MP_OK)
return imath_errno = res, 0;
if((res = mp_int_exptmod_bvalue(v, in[1], in[2], in[3])) != expect)
return imath_errno = res, 0;
if(expect == MP_OK && mp_int_compare(in[3], out[0]) != 0) {
mp_int_to_string(in[3], 10, g_output, OUTPUT_LIMIT);
return imath_errno = OTHER_ERROR, 0;
}
return 1;
}