// IsOnCurve, all other behavior is undefined.
func TestInvalidCoordinates(t *testing.T) {
	t.Parallel()
	testAllCurves(t, testInvalidCoordinates)
}

func testInvalidCoordinates(t *testing.T, curve Curve) {
	checkIsOnCurveFalse := func(name string, x, y *big.Int) {
		if curve.IsOnCurve(x, y) {
			t.Errorf("IsOnCurve(%s) unexpectedly returned true", name)
		}
	}

		y.Neg(y).Mod(y, p)
	}
	if !curve.IsOnCurve(x, y) {
		return nil, nil
	}
	return
}

func panicIfNotOnCurve(curve Curve, x, y *big.Int) {
	// (0, 0) is the point at infinity by convention. It's ok to operate on it,
	// although IsOnCurve is documented to return false for it. See Issue 37294.
	if x.Sign() == 0 && y.Sign() == 0 {
		return
	}

	if !curve.IsOnCurve(x, y) {

	return x3
}

// IsOnCurve implements [Curve.IsOnCurve].
//
// Deprecated: the [CurveParams] methods are deprecated and are not guaranteed to
// provide any security property. For ECDH, use the [crypto/ecdh] package.
// For ECDSA, use the [crypto/ecdsa] package with a [Curve] value returned directly
// from [P224], [P256], [P384], or [P521].
func (curve *CurveParams) IsOnCurve(x, y *big.Int) bool {

	ScalarMult(T, []byte) (T, error)
	ScalarBaseMult([]byte) (T, error)
}

func (curve *nistCurve[Point]) Params() *CurveParams {
	return curve.params
}

func (curve *nistCurve[Point]) IsOnCurve(x, y *big.Int) bool {
	// IsOnCurve is documented to reject (0, 0), the conventional point at
	// infinity, which however is accepted by pointFromAffine.
	if x.Sign() == 0 && y.Sign() == 0 {
		return false
	}

	p224 := P224()
	pointData, _ := hex.DecodeString("049B535B45FB0A2072398A6831834624C7E32CCFD5A4B933BCEAF77F1DD945E08BBE5178F5EDF5E733388F196D2A631D2E075BB16CBFEEA15B")
	x, y := Unmarshal(p224, pointData)
	if !p224.IsOnCurve(x, y) {
		t.Error("P224 failed to validate a correct point")
	}

// sets the curve ID to the given OID, or omits it if OID is nil.
func marshalECPrivateKeyWithOID(key *ecdsa.PrivateKey, oid asn1.ObjectIdentifier) ([]byte, error) {
	if !key.Curve.IsOnCurve(key.X, key.Y) {
		return nil, errors.New("invalid elliptic key public key")
	}
	privateKey := make([]byte, (key.Curve.Params().N.BitLen()+7)/8)
	return asn1.Marshal(ecPrivateKey{
		Version:       1,

pkg crypto/elliptic, method (*CurveParams) IsOnCurve //deprecated #34648
pkg crypto/elliptic, method (*CurveParams) ScalarBaseMult //deprecated #34648
pkg crypto/elliptic, method (*CurveParams) ScalarMult //deprecated #34648
pkg crypto/elliptic, type Curve interface, Add //deprecated #52221
pkg crypto/elliptic, type Curve interface, Double //deprecated #52221
pkg crypto/elliptic, type Curve interface, IsOnCurve //deprecated #52221

	testAllCurves(t, testKeyGeneration)
}

func testKeyGeneration(t *testing.T, c elliptic.Curve) {
	priv, err := GenerateKey(c, rand.Reader)
	if err != nil {
		t.Fatal(err)
	}
	if !c.IsOnCurve(priv.PublicKey.X, priv.PublicKey.Y) {
		t.Errorf("public key invalid: %s", err)
	}
}

func TestSignAndVerify(t *testing.T) {
	testAllCurves(t, testSignAndVerify)
}

// Curve is not supported by crypto/ecdh.
func (k *PublicKey) ECDH() (*ecdh.PublicKey, error) {
	c := curveToECDH(k.Curve)
	if c == nil {
		return nil, errors.New("ecdsa: unsupported curve by crypto/ecdh")
	}
	if !k.Curve.IsOnCurve(k.X, k.Y) {
		return nil, errors.New("ecdsa: invalid public key")
	}
	return c.NewPublicKey(elliptic.Marshal(k.Curve, k.X, k.Y))
}

// Equal reports whether pub and x have the same value.
//

	case *ecdsa.PublicKey:
		oid, ok := oidFromNamedCurve(pub.Curve)
		if !ok {
			return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: unsupported elliptic curve")
		}
		if !pub.Curve.IsOnCurve(pub.X, pub.Y) {
			return nil, pkix.AlgorithmIdentifier{}, errors.New("x509: invalid elliptic curve public key")
		}
		publicKeyBytes = elliptic.Marshal(pub.Curve, pub.X, pub.Y)