Main.java Source code

Introduction

Here is the source code for Main.java

Source

//package com.java2s;

import java.security.InvalidKeyException;

import java.security.NoSuchAlgorithmException;
import java.security.SecureRandom;
import java.security.spec.InvalidKeySpecException;

import javax.crypto.BadPaddingException;
import javax.crypto.Cipher;
import javax.crypto.IllegalBlockSizeException;

import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;

public class Main {
    private static final String DEFAULT_KEY = "ZLXTYLSD";
    private final static String DES = "DES";
    private final static String MODE = "DES/ECB/PKCS5Padding";

    public static byte[] decryptMessage(String key, byte[] input) throws Exception {
        if ((input == null) || (input.length <= 0)) {
            return null;
        }
        try {
            return doFinal(key, Cipher.DECRYPT_MODE, input);
        } catch (Exception e) {
            throw new Exception("201");
        }
    }

    private static byte[] doFinal(String key, int opmode, byte[] input)
            throws InvalidKeyException, NoSuchAlgorithmException, InvalidKeySpecException, NoSuchPaddingException,
            IllegalBlockSizeException, BadPaddingException {
        key = checkNull(key) ? DEFAULT_KEY : key;
        if (checkNull(key)) {
            return null;
        }
        SecureRandom sr = new SecureRandom();
        DESKeySpec dks = new DESKeySpec(key.getBytes());
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey securekey = keyFactory.generateSecret(dks);
        Cipher cipher = Cipher.getInstance(MODE);
        cipher.init(opmode, securekey, sr);
        return cipher.doFinal(input);
    }

    public static boolean checkNull(String input) {
        if (input == null || input.length() == 0)
            return true;
        else
            return false;
    }
}