-#include <tommath.h>
+#include "tommath_private.h"
#ifdef BN_MP_PRIME_NEXT_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@gmail.com, http://libtom.org
- */
+/* LibTomMath, multiple-precision integer library -- Tom St Denis */
+/* SPDX-License-Identifier: Unlicense */
/* finds the next prime after the number "a" using "t" trials
* of Miller-Rabin.
*
* bbs_style = 1 means the prime must be congruent to 3 mod 4
*/
-int mp_prime_next_prime(mp_int *a, int t, int bbs_style)
+mp_err mp_prime_next_prime(mp_int *a, int t, int bbs_style)
{
- int err, res = MP_NO, x, y;
- mp_digit res_tab[PRIME_SIZE], step, kstep;
+ int x, y;
+ mp_ord cmp;
+ mp_err err;
+ mp_bool res = MP_NO;
+ mp_digit res_tab[PRIVATE_MP_PRIME_TAB_SIZE], step, kstep;
mp_int b;
- /* ensure t is valid */
- if (t <= 0 || t > PRIME_SIZE) {
- return MP_VAL;
- }
-
/* force positive */
a->sign = MP_ZPOS;
/* simple algo if a is less than the largest prime in the table */
- if (mp_cmp_d(a, ltm_prime_tab[PRIME_SIZE-1]) == MP_LT) {
- /* find which prime it is bigger than */
- for (x = PRIME_SIZE - 2; x >= 0; x--) {
- if (mp_cmp_d(a, ltm_prime_tab[x]) != MP_LT) {
- if (bbs_style == 1) {
- /* ok we found a prime smaller or
- * equal [so the next is larger]
- *
- * however, the prime must be
- * congruent to 3 mod 4
- */
- if ((ltm_prime_tab[x + 1] & 3) != 3) {
- /* scan upwards for a prime congruent to 3 mod 4 */
- for (y = x + 1; y < PRIME_SIZE; y++) {
- if ((ltm_prime_tab[y] & 3) == 3) {
- mp_set(a, ltm_prime_tab[y]);
- return MP_OKAY;
- }
- }
- }
- } else {
- mp_set(a, ltm_prime_tab[x + 1]);
- return MP_OKAY;
- }
- }
- }
- /* at this point a maybe 1 */
- if (mp_cmp_d(a, 1) == MP_EQ) {
- mp_set(a, 2);
- return MP_OKAY;
+ if (mp_cmp_d(a, s_mp_prime_tab[PRIVATE_MP_PRIME_TAB_SIZE-1]) == MP_LT) {
+ /* find which prime it is bigger than "a" */
+ for (x = 0; x < PRIVATE_MP_PRIME_TAB_SIZE; x++) {
+ cmp = mp_cmp_d(a, s_mp_prime_tab[x]);
+ if (cmp == MP_EQ) {
+ continue;
+ }
+ if (cmp != MP_GT) {
+ if ((bbs_style == 1) && ((s_mp_prime_tab[x] & 3u) != 3u)) {
+ /* try again until we get a prime congruent to 3 mod 4 */
+ continue;
+ } else {
+ mp_set(a, s_mp_prime_tab[x]);
+ return MP_OKAY;
+ }
+ }
}
/* fall through to the sieve */
}
if (bbs_style == 1) {
/* if a mod 4 != 3 subtract the correct value to make it so */
- if ((a->dp[0] & 3) != 3) {
- if ((err = mp_sub_d(a, (a->dp[0] & 3) + 1, a)) != MP_OKAY) { return err; };
+ if ((a->dp[0] & 3u) != 3u) {
+ if ((err = mp_sub_d(a, (a->dp[0] & 3u) + 1u, a)) != MP_OKAY) {
+ return err;
+ }
}
} else {
- if (mp_iseven(a) == 1) {
+ if (MP_IS_EVEN(a)) {
/* force odd */
- if ((err = mp_sub_d(a, 1, a)) != MP_OKAY) {
+ if ((err = mp_sub_d(a, 1uL, a)) != MP_OKAY) {
return err;
}
}
}
/* generate the restable */
- for (x = 1; x < PRIME_SIZE; x++) {
- if ((err = mp_mod_d(a, ltm_prime_tab[x], res_tab + x)) != MP_OKAY) {
+ for (x = 1; x < PRIVATE_MP_PRIME_TAB_SIZE; x++) {
+ if ((err = mp_mod_d(a, s_mp_prime_tab[x], res_tab + x)) != MP_OKAY) {
return err;
}
}
step += kstep;
/* compute the new residue without using division */
- for (x = 1; x < PRIME_SIZE; x++) {
- /* add the step to each residue */
- res_tab[x] += kstep;
-
- /* subtract the modulus [instead of using division] */
- if (res_tab[x] >= ltm_prime_tab[x]) {
- res_tab[x] -= ltm_prime_tab[x];
- }
-
- /* set flag if zero */
- if (res_tab[x] == 0) {
- y = 1;
- }
+ for (x = 1; x < PRIVATE_MP_PRIME_TAB_SIZE; x++) {
+ /* add the step to each residue */
+ res_tab[x] += kstep;
+
+ /* subtract the modulus [instead of using division] */
+ if (res_tab[x] >= s_mp_prime_tab[x]) {
+ res_tab[x] -= s_mp_prime_tab[x];
+ }
+
+ /* set flag if zero */
+ if (res_tab[x] == 0u) {
+ y = 1;
+ }
}
- } while (y == 1 && step < ((((mp_digit)1)<<DIGIT_BIT) - kstep));
+ } while ((y == 1) && (step < (((mp_digit)1 << MP_DIGIT_BIT) - kstep)));
/* add the step */
if ((err = mp_add_d(a, step, a)) != MP_OKAY) {
goto LBL_ERR;
}
- /* if didn't pass sieve and step == MAX then skip test */
- if (y == 1 && step >= ((((mp_digit)1)<<DIGIT_BIT) - kstep)) {
+ /* if didn't pass sieve and step == MP_MAX then skip test */
+ if ((y == 1) && (step >= (((mp_digit)1 << MP_DIGIT_BIT) - kstep))) {
continue;
}
- /* is this prime? */
- for (x = 0; x < t; x++) {
- mp_set(&b, ltm_prime_tab[t]);
- if ((err = mp_prime_miller_rabin(a, &b, &res)) != MP_OKAY) {
- goto LBL_ERR;
- }
- if (res == MP_NO) {
- break;
- }
+ if ((err = mp_prime_is_prime(a, t, &res)) != MP_OKAY) {
+ goto LBL_ERR;
}
-
if (res == MP_YES) {
break;
}
}
#endif
-
-/* $Source: /cvs/libtom/libtommath/bn_mp_prime_next_prime.c,v $ */
-/* $Revision: 1.4 $ */
-/* $Date: 2006/12/28 01:25:13 $ */
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