Using other modes except ECB and decrypting with DES will throw “invalidkeyexception: missing parameter”

I basically use http://www.avajava.com/tutorials/lessons/how-do-i-encrypt-and-decrypt-files-using-des.html The code encrypts the application, but I want to be able to select the operation mode, so I added this:

private String key;
private static String algorithmMode;

    public DESCrypt(String password,String algorithmMode) {
        this.key = password;
        this.algorithmMode = "DES/" + algorithmMode + "/PKCS5Padding";
    }

The main looks like this:

public static void main(String[] args) {
        try {
            DESCrypt des = new DESCrypt("12345678",algorithmMode);

            // FileInputStream fis1 = new FileInputStream("d:\\_test.txt");
            // FileOutputStream fos1 = new FileOutputStream("d:\\_test.txt.des");
            // des.encrypt(fis1,fos1);

            FileInputStream fis = new FileInputStream("d:\\_test.txt.des");
            FileOutputStream fos = new FileOutputStream("d:\\_test.txt");
            des.decrypt(fis,fos);
        } catch (Exception e) {
            e.printStackTrace();
        }
    }

As I said in the title, it can be used with ECB, but in other modes, I can only encrypt

Solution

You are missing the decrypted IV value You need to be in cipher This is included in the init call:

... Cipher.init(Cipher.DECRYPT,someKey,new IvParameterSpec(eightByteValue));

If it is omitted from the encryption code, a random IV value is generated You need to store it (retrieved through cipher. Getiv()) for use in your decryption code