55 lines
1.2 KiB
C
55 lines
1.2 KiB
C
/* LibTomMath, multiple-precision integer library -- Tom St Denis
|
|
*
|
|
* LibTomMath is library that provides for multiple-precision
|
|
* integer arithmetic as well as number theoretic functionality.
|
|
*
|
|
* The library is 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
|
|
*/
|
|
#include <tommath.h>
|
|
|
|
/* finds the next prime after the number "a" using "t" trials
|
|
* of Miller-Rabin.
|
|
*/
|
|
int mp_prime_next_prime(mp_int *a, int t)
|
|
{
|
|
int err, res;
|
|
|
|
if (mp_iseven(a) == 1) {
|
|
/* force odd */
|
|
if ((err = mp_add_d(a, 1, a)) != MP_OKAY) {
|
|
return err;
|
|
}
|
|
} else {
|
|
/* force to next odd number */
|
|
if ((err = mp_add_d(a, 2, a)) != MP_OKAY) {
|
|
return err;
|
|
}
|
|
}
|
|
|
|
for (;;) {
|
|
/* is this prime? */
|
|
if ((err = mp_prime_is_prime(a, t, &res)) != MP_OKAY) {
|
|
return err;
|
|
}
|
|
|
|
if (res == 1) {
|
|
break;
|
|
}
|
|
|
|
/* add two, next candidate */
|
|
if ((err = mp_add_d(a, 2, a)) != MP_OKAY) {
|
|
return err;
|
|
}
|
|
}
|
|
|
|
return MP_OKAY;
|
|
}
|
|
|