Add secp256k1_fe_is_square_var function

The implementation calls the secp256k1_modinvNN_jacobi_var code, falling back to computing a square root in the (extremely rare) case it failed converge.
2023-01-04 16:05:34 -05:00
parent 1de2a01c2b
commit 6be01036c8
5 changed files with 73 additions and 0 deletions
--- a/src/field.h
+++ b/src/field.h
@@ -135,4 +135,7 @@ static void secp256k1_fe_half(secp256k1_fe *r);
 *  magnitude set to 'm' and is normalized if (and only if) 'm' is zero. */
 static void secp256k1_fe_get_bounds(secp256k1_fe *r, int m);

+/** Determine whether a is a square (modulo p). */
+static int secp256k1_fe_is_square_var(const secp256k1_fe *a);
+
 #endif /* SECP256K1_FIELD_H */