case *ecdsa.PrivateKey:
			b, err := x509.MarshalECPrivateKey(k)
			if err != nil {
				fmt.Fprintf(os.Stderr, "Unable to marshal ECDSA private key: %v", err)
				os.Exit(2)
			}
			return &pem.Block{Type: "EC PRIVATE KEY", Bytes: b}
		default:
			return nil
		}
	}

	var priv interface{}
	var err error
	priv, err = rsa.GenerateKey(crand.Reader, rsaBits)
	if err != nil {