}
	err = pem.Encode(privatePem, privateKeyBlock)
	if err != nil {
		fmt.Printf("error when encode private pem: %s n", err)
		os.Exit(1)
	}

	// dump public key to file
	publicKeyBytes := x509.MarshalPKCS1PublicKey(&privatekey.PublicKey)
	if err != nil {
		fmt.Printf("error when dumping publickey: %s n", err)
		os.Exit(1)
	}
	publicKeyBlock := &pem.Block{
		Type:  "PUBLIC KEY",
		Bytes: publicKeyBytes,
	}

		E: 3,
	}
	derBytes := MarshalPKCS1PublicKey(pub)
	pub2, err := ParsePKCS1PublicKey(derBytes)
	if err != nil {
		t.Errorf("ParsePKCS1PublicKey: %s", err)
	}
	if pub.N.Cmp(pub2.N) != 0 || pub.E != pub2.E {