_, _, err := randomPoint(p384(), rand)
		return err
	case elliptic.P521().Params():
		_, _, err := randomPoint(p521(), rand)
		return err
	default:
		panic("unknown curve")
	}
}

func benchmarkAllCurves(b *testing.B, f func(*testing.B, elliptic.Curve)) {
	tests := []struct {
		name  string
		curve elliptic.Curve
	}{
		{"P256", elliptic.P256()},
		{"P384", elliptic.P384()},
		{"P521", elliptic.P521()},

	t.Run("P521", func(t *testing.T) { f(t, ecdh.P521()) })
	t.Run("X25519", func(t *testing.T) { f(t, ecdh.X25519()) })
}

func BenchmarkECDH(b *testing.B) {
	benchmarkAllCurves(b, func(b *testing.B, curve ecdh.Curve) {
		c, err := chacha20.NewUnauthenticatedCipher(make([]byte, 32), make([]byte, 12))
		if err != nil {
			b.Fatal(err)
		}
		rand := cipher.StreamReader{