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Merge pull request #144 from czurnieden/develop

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reg. #143 corrected translation of mpz_fdiv_q_2exp
This commit is contained in:
Steffen Jaeckel 2018-12-31 11:53:25 +01:00 committed by GitHub
commit 62adf47fb8
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GPG Key ID: 4AEE18F83AFDEB23
2 changed files with 18 additions and 9 deletions
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17
bn_mp_prime_strong_lucas_selfridge.c
View File

@ -58,9 +58,6 @@ LBL_MPMULSI_ERR:
mp_clear(&t); mp_clear(&t);
return err; return err;
} }
/* /*
Strong Lucas-Selfridge test. Strong Lucas-Selfridge test.
returns MP_YES if it is a strong L-S prime, MP_NO if it is composite 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 */ /* 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; int32_t D, Ds, J, sign, P, Q, r, s, u, Nbits;
int e; int e;
int isset; int isset, oddness;
*result = MP_NO; *result = MP_NO;
/* /*
Find the first element D in the sequence {5, -7, 9, -11, 13, ...} Find the first element D in the sequence {5, -7, 9, -11, 13, ...}
such that Jacobi(D,N) = -1 (Selfridge's algorithm). Theory 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 */ P = 1; /* Selfridge's choice */
Q = (1 - Ds) / 4; /* Required so D = P*P - 4*Q */ 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); Nbits = mp_count_bits(&Dz);
for (u = 1; u < Nbits; u++) { /* zero bit off, already accounted for */ for (u = 1; u < Nbits; u++) { /* zero bit off, already accounted for */
/* Formulas for doubling of indices (carried out mod N). Note that /* Formulas for doubling of indices (carried out mod N). Note that
* the indices denoted as "2m" are actually powers of 2, specifically * 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) { if ((e = mp_mul_2(&Qmz, &Q2mz)) != MP_OKAY) {
goto LBL_LS_ERR; goto LBL_LS_ERR;
} }
if ((isset = mp_get_bit(&Dz, u)) == MP_VAL) { if ((isset = mp_get_bit(&Dz, u)) == MP_VAL) {
e = isset; e = isset;
goto LBL_LS_ERR; 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)! * Be careful with division by 2 (mod N)!
*/ */
if ((e = mp_mul(&U2mz, &Vz, &T1z)) != MP_OKAY) { if ((e = mp_mul(&U2mz, &Vz, &T1z)) != MP_OKAY) {
goto LBL_LS_ERR; 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(). * Thomas R. Nicely used GMP's mpz_fdiv_q_2exp().
* But mp_div_2() does not do so, it is truncating instead. * 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) { if ((e = mp_div_2(&Uz, &Uz)) != MP_OKAY) {
goto LBL_LS_ERR; 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) { if ((e = mp_sub_d(&Uz, 1uL, &Uz)) != MP_OKAY) {
goto LBL_LS_ERR; goto LBL_LS_ERR;
} }
@ -325,10 +323,11 @@ int mp_prime_strong_lucas_selfridge(const mp_int *a, int *result)
goto LBL_LS_ERR; goto LBL_LS_ERR;
} }
} }
oddness = mp_isodd(&Vz);
if ((e = mp_div_2(&Vz, &Vz)) != MP_OKAY) { if ((e = mp_div_2(&Vz, &Vz)) != MP_OKAY) {
goto LBL_LS_ERR; 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) { if ((e = mp_sub_d(&Vz, 1uL, &Vz)) != MP_OKAY) {
goto LBL_LS_ERR; goto LBL_LS_ERR;
} }

10
demo/demo.c
View File

@ -715,6 +715,16 @@ int main(void)
return EXIT_FAILURE; 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"); printf("\n\n");