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Merge branch 'fix/jacobi' into develop 

This closes #31
This commit is contained in:
Steffen Jaeckel 2015-11-29 23:12:43 +01:00
parent 6c536e4bd0 7176a8777a
commit 6d4467daba
2 changed files with 56 additions and 10 deletions
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25
bn_mp_jacobi.c
View File

@ -17,22 +17,29 @@
/* computes the jacobi c = (a | n) (or Legendre if n is prime)
* HAC pp. 73 Algorithm 2.149
* HAC is wrong here, as the special case of (0 | 1) is not
* handled correctly.
*/
int mp_jacobi (mp_int * a, mp_int * p, int *c)
int mp_jacobi (mp_int * a, mp_int * n, int *c)
{
mp_int a1, p1;
int k, s, r, res;
mp_digit residue;
/* if p <= 0 return MP_VAL */
if (mp_cmp_d(p, 0) != MP_GT) {
/* if n <= 0 return MP_VAL */
if (mp_cmp_d(n, 0) != MP_GT) {
return MP_VAL;
}
/* step 1. if a == 0, return 0 */
/* step 1. handle case of a == 0 */
if (mp_iszero (a) == MP_YES) {
*c = 0;
return MP_OKAY;
/* special case of a == 0 and n == 1 */
if (mp_cmp_d (n, 1) == MP_EQ) {
*c = 1;
} else {
*c = 0;
}
return MP_OKAY;
}
/* step 2. if a == 1, return 1 */
@ -64,7 +71,7 @@ int mp_jacobi (mp_int * a, mp_int * p, int *c)
s = 1;
} else {
/* else set s=1 if p = 1/7 (mod 8) or s=-1 if p = 3/5 (mod 8) */
residue = p->dp[0] & 7;
residue = n->dp[0] & 7;
if (residue == 1 || residue == 7) {
s = 1;
@ -74,7 +81,7 @@ int mp_jacobi (mp_int * a, mp_int * p, int *c)
}
/* step 5. if p == 3 (mod 4) *and* a1 == 3 (mod 4) then s = -s */
if ( ((p->dp[0] & 3) == 3) && ((a1.dp[0] & 3) == 3)) {
if ( ((n->dp[0] & 3) == 3) && ((a1.dp[0] & 3) == 3)) {
s = -s;
}
@ -83,7 +90,7 @@ int mp_jacobi (mp_int * a, mp_int * p, int *c)
*c = s;
} else {
/* n1 = n mod a1 */
if ((res = mp_mod (p, &a1, &p1)) != MP_OKAY) {
if ((res = mp_mod (n, &a1, &p1)) != MP_OKAY) {
goto LBL_P1;
}
if ((res = mp_jacobi (&p1, &a1, &r)) != MP_OKAY) {

41
demo/demo.c
View File

@ -12,7 +12,7 @@
* Configuration
*/
#ifndef LTM_DEMO_TEST_VS_MTEST
#define LTM_DEMO_TEST_VS_MTEST 1
#define LTM_DEMO_TEST_VS_MTEST 0
#endif
#ifndef LTM_DEMO_TEST_REDUCE_2K_L
@ -114,6 +114,16 @@ struct mp_sqrtmod_prime_st sqrtmod_prime[] = {
{ 7, 9, 4 },
{ 113, 2, 62 }
};
struct mp_jacobi_st {
unsigned long n;
int c[16];
};
struct mp_jacobi_st jacobi[] = {
{ 3, { 1, -1, 0, 1, -1, 0, 1, -1, 0, 1, -1, 0, 1, -1, 0, 1 } },
{ 5, { 0, 1, -1, -1, 1, 0, 1, -1, -1, 1, 0, 1, -1, -1, 1, 0 } },
{ 7, { 1, -1, 1, -1, -1, 0, 1, 1, -1, 1, -1, -1, 0, 1, 1, -1 } },
{ 9, { -1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1, 1, 0, 1 } },
};
char cmd[4096], buf[4096];
int main(void)
@ -186,6 +196,35 @@ int main(void)
mp_add_d(&a, 1, &b);
mp_add_d(&a, 6, &b);
mp_set_int(&a, 0);
mp_set_int(&b, 1);
if ((ix = mp_jacobi(&a, &b, &i)) != MP_OKAY) {
printf("Failed executing mp_jacobi(0 | 1) %s.\n", mp_error_to_string(ix));
return EXIT_FAILURE;
}
if (i != 1) {
printf("Failed trivial mp_jacobi(0 | 1) %d != 1\n", i);
return EXIT_FAILURE;
}
for (cnt = 0; cnt < (int)(sizeof(jacobi)/sizeof(jacobi[0])); ++cnt) {
mp_set_int(&b, jacobi[cnt].n);
/* only test positive values of a */
// for (n = -5; n <= 10; ++n) {
for (n = 0; n <= 10; ++n) {
mp_set_int(&a, abs(n));
if (n < 0) mp_neg(&a, &a);
if ((ix = mp_jacobi(&a, &b, &i)) != MP_OKAY) {
printf("Failed executing mp_jacobi(%d | %lu) %s.\n", n, jacobi[cnt].n, mp_error_to_string(ix));
return EXIT_FAILURE;
}
if (i != jacobi[cnt].c[n + 5]) {
printf("Failed trivial mp_jacobi(%d | %lu) %d != %d\n", n, jacobi[cnt].n, i, jacobi[cnt].c[n + 5]);
return EXIT_FAILURE;
}
}
}
// test montgomery
printf("Testing: montgomery...\n");
for (i = 1; i <= 10; i++) {