// 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)
	}