return nil, errMalformedJWKECKey
		}

		var curve elliptic.Curve
		switch key.Crv {
		case "P-224":
			curve = elliptic.P224()
		case "P-256":
			curve = elliptic.P256()
		case "P-384":
			curve = elliptic.P384()
		case "P-521":
			curve = elliptic.P521()
		default:
			return nil, fmt.Errorf("Unknown curve type: %s", key.Crv)
		}

		xbuf, err := base64.RawURLEncoding.DecodeString(key.X)

		t.Fatalf("Expected ECDSA key[0], got %T", keys[0])
	} else if key1, ok := keys[1].(*rsa.PublicKey); !ok {
		t.Fatalf("Expected RSA key[1], got %T", keys[1])
	} else if key0.Curve != elliptic.P256() {
		t.Fatal("Key[0] is not using P-256 curve")
	} else if !bytes.Equal(key0.X.Bytes(), []byte{
		0x30, 0xa0, 0x42, 0x4c, 0xd2,
		0x1c, 0x29, 0x44, 0x83, 0x8a, 0x2d, 0x75, 0xc9, 0x2b, 0x37, 0xe7, 0x6e, 0xa2,

// TLSCurveIDs returns a list of supported elliptic curve IDs
// in preference order.
func TLSCurveIDs() []tls.CurveID {
	var curves []tls.CurveID
	if !Enabled {
		curves = append(curves, tls.X25519) // Only enable X25519 in non-FIPS mode
	}
	curves = append(curves, tls.CurveP256)
	if go19 {
		// With go1.19 enable P384, P521 newer constant time implementations.
		curves = append(curves, tls.CurveP384, tls.CurveP521)
	}