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Implement handling of special case (0 | 1)

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This commit is contained in:
Steffen Jaeckel 2015-11-25 21:24:21 +01:00
parent ce70362ace
commit 34e6b723ff
1 changed files with 10 additions and 3 deletions
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13
bn_mp_jacobi.c
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@ -17,6 +17,8 @@
/* computes the jacobi c = (a | n) (or Legendre if n is prime) /* computes the jacobi c = (a | n) (or Legendre if n is prime)
* HAC pp. 73 Algorithm 2.149 * 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 * n, int *c) int mp_jacobi (mp_int * a, mp_int * n, int *c)
{ {
@ -29,10 +31,15 @@ int mp_jacobi (mp_int * a, mp_int * n, int *c)
return MP_VAL; return MP_VAL;
} }
/* step 1. if a == 0, return 0 */ /* step 1. handle case of a == 0 */
if (mp_iszero (a) == MP_YES) { if (mp_iszero (a) == MP_YES) {
*c = 0; /* special case of a == 0 and n == 1 */
return MP_OKAY; if (mp_cmp_d (n, 1) == MP_EQ) {
*c = 1;
} else {
*c = 0;
}
return MP_OKAY;
} }
/* step 2. if a == 1, return 1 */ /* step 2. if a == 1, return 1 */