Commit 62adf47fb8b96fa11def1291a20126598a5dc110
2018-12-31T11:53:25
Merge pull request #144 from czurnieden/develop reg. #143 corrected translation of mpz_fdiv_q_2exp
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diff --git a/bn_mp_prime_strong_lucas_selfridge.c b/bn_mp_prime_strong_lucas_selfridge.c
index ca15e3c..5a94f8e 100644
--- a/bn_mp_prime_strong_lucas_selfridge.c
+++ b/bn_mp_prime_strong_lucas_selfridge.c
@@ -58,9 +58,6 @@ LBL_MPMULSI_ERR:
mp_clear(&t);
return err;
}
-
-
-
/*
Strong Lucas-Selfridge test.
returns MP_YES if it is a strong L-S prime, MP_NO if it is composite
@@ -85,10 +82,9 @@ int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result)
/* CZ TODO: Some of them need the full 32 bit, hence the (temporary) exclusion of MP_8BIT */
int32_t D, Ds, J, sign, P, Q, r, s, u, Nbits;
int e;
- int isset;
+ int isset, oddness;
*result = MP_NO;
-
/*
Find the first element D in the sequence {5, -7, 9, -11, 13, ...}
such that Jacobi(D,N) = -1 (Selfridge's algorithm). Theory
@@ -138,6 +134,8 @@ int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result)
}
}
+
+
P = 1; /* Selfridge's choice */
Q = (1 - Ds) / 4; /* Required so D = P*P - 4*Q */
@@ -232,6 +230,7 @@ int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result)
}
Nbits = mp_count_bits(&Dz);
+
for (u = 1; u < Nbits; u++) { /* zero bit off, already accounted for */
/* Formulas for doubling of indices (carried out mod N). Note that
* the indices denoted as "2m" are actually powers of 2, specifically
@@ -267,7 +266,6 @@ int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result)
if ((e = mp_mul_2(&Qmz, &Q2mz)) != MP_OKAY) {
goto LBL_LS_ERR;
}
-
if ((isset = mp_get_bit(&Dz, u)) == MP_VAL) {
e = isset;
goto LBL_LS_ERR;
@@ -280,7 +278,6 @@ int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result)
*
* Be careful with division by 2 (mod N)!
*/
-
if ((e = mp_mul(&U2mz, &Vz, &T1z)) != MP_OKAY) {
goto LBL_LS_ERR;
}
@@ -309,10 +306,11 @@ int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result)
* Thomas R. Nicely used GMP's mpz_fdiv_q_2exp().
* But mp_div_2() does not do so, it is truncating instead.
*/
+ oddness = mp_isodd(&Uz);
if ((e = mp_div_2(&Uz, &Uz)) != MP_OKAY) {
goto LBL_LS_ERR;
}
- if ((Uz.sign == MP_NEG) && (mp_isodd(&Uz) != MP_NO)) {
+ if ((Uz.sign == MP_NEG) && (oddness != MP_NO)) {
if ((e = mp_sub_d(&Uz, 1uL, &Uz)) != MP_OKAY) {
goto LBL_LS_ERR;
}
@@ -325,10 +323,11 @@ int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result)
goto LBL_LS_ERR;
}
}
+ oddness = mp_isodd(&Vz);
if ((e = mp_div_2(&Vz, &Vz)) != MP_OKAY) {
goto LBL_LS_ERR;
}
- if ((Vz.sign == MP_NEG) && (mp_isodd(&Vz) != MP_NO)) {
+ if ((Vz.sign == MP_NEG) && (oddness != MP_NO)) {
if ((e = mp_sub_d(&Vz, 1uL, &Vz)) != MP_OKAY) {
goto LBL_LS_ERR;
}
diff --git a/demo/demo.c b/demo/demo.c
index a93ce1d..0aeae25 100644
--- a/demo/demo.c
+++ b/demo/demo.c
@@ -715,6 +715,16 @@ int main(void)
return EXIT_FAILURE;
}
}
+ /* Check regarding problem #143 */
+#ifndef MP_8BIT
+ mp_read_radix(&a, "FFFFFFFFFFFFFFFFC90FDAA22168C234C4C6628B80DC1CD129024E088A67CC74020BBEA63B139B22514A08798E3404DDEF9519B3CD3A431B302B0A6DF25F14374FE1356D6D51C245E485B576625E7EC6F44C42E9A63A3620FFFFFFFFFFFFFFFF",
+ 16);
+ mp_prime_strong_lucas_selfridge(&a, &cnt);
+ if (cnt != MP_YES) {
+ printf("\n\nissue #143 - mp_prime_strong_lucas_selfridge FAILED!\n");
+ return EXIT_FAILURE;
+ }
+#endif
printf("\n\n");