from "ecc/babyjubjubParams" import BabyJubJubParams;

// Check if a point is on a twisted Edwards curve
// Curve parameters are defined with the last argument
// See appendix 3.3.1 of Zcash protocol specification:
// https://github.com/zcash/zips/blob/master/protocol/protocol.pdf
def main(field[2] pt, BabyJubJubParams context) -> bool {
    field a = context.JUBJUB_A;
    field d = context.JUBJUB_D;

    field uu = pt[0] * pt[0];
    field vv = pt[1] * pt[1];
    field uuvv = uu * vv;

    assert(a * uu + vv == 1 + d * uuvv);
    return true;
}