import sun.misc.BASE64Decoder;
import sun.misc.BASE64Encoder;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import java.io.IOException;
import java.security.SecureRandom;

/**
 * DES加密演算法
 * Created by lipeng on 2017/6/6.
 */
public class DesUtil {

    private final static String DES = "DES";
    private final static String ENCODE = "GBK";
    private final static String defaultKey = "qkxTskldu";

    public static void main(String[] args) throws Exception {
        String data = "測試ss";
        System.out.println(encrypt(data));
        System.out.println(decrypt(encrypt(data)));

    }

    /**
     * 使用 預設key 加密
     *
     * @return String
     * @author lifq
     * @date 2015-3-17 下午02:46:43
     */
    public static String encrypt(String data) throws Exception {
        byte[] bt = encrypt(data.getBytes(ENCODE), defaultKey.getBytes(ENCODE));
        String strs = new BASE64Encoder().encode(bt);
        return strs;
    }

    /**
     * 使用 預設key 解密
     *
     * @return String
     * @author lifq
     * @date 2015-3-17 下午02:49:52
     */
    public static String decrypt(String data) throws IOException, Exception {
        if (data == null)
            return null;
        BASE64Decoder decoder = new BASE64Decoder();
        byte[] buf = decoder.decodeBuffer(data);
        byte[] bt = decrypt(buf, defaultKey.getBytes(ENCODE));
        return new String(bt, ENCODE);
    }

    /**
     * Description 根據鍵值進行加密
     *
     * @param data
     * @param key
     *            加密鍵byte陣列
     * @return
     * @throws Exception
     */
    public static String encrypt(String data, String key) throws Exception {
        byte[] bt = encrypt(data.getBytes(ENCODE), defaultKey.getBytes(ENCODE));
        String strs = new BASE64Encoder().encode(bt);
        return strs;
    }

    /**
     * Description 根據鍵值進行解密
     *
     * @param data
     * @param key
     *            加密鍵byte陣列
     * @return
     * @throws IOException
     * @throws Exception
     */
    public static String decrypt(String data, String key) throws IOException,
            Exception {
        if (data == null)
            return null;
        BASE64Decoder decoder = new BASE64Decoder();
        byte[] buf = decoder.decodeBuffer(data);
        byte[] bt = decrypt(buf, key.getBytes(ENCODE));
        return new String(bt, ENCODE);
    }

    /**
     * Description 根據鍵值進行加密
     *
     * @param data
     * @param key
     *            加密鍵byte陣列
     * @return
     * @throws Exception
     */
    private static byte[] encrypt(byte[] data, byte[] key) throws Exception {
        // 生成一個可信任的隨機數源
        SecureRandom sr = new SecureRandom();

        // 從原始金鑰資料建立DESKeySpec物件
        DESKeySpec dks = new DESKeySpec(key);

        // 建立一個金鑰工廠，然後用它把DESKeySpec轉換成SecretKey物件
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey securekey = keyFactory.generateSecret(dks);

        // Cipher物件實際完成加密操作
        Cipher cipher = Cipher.getInstance(DES);

        // 用金鑰初始化Cipher物件
        cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);

        return cipher.doFinal(data);
    }

    /**
     * Description 根據鍵值進行解密
     *
     * @param data
     * @param key
     *            加密鍵byte陣列
     * @return
     * @throws Exception
     */
    private static byte[] decrypt(byte[] data, byte[] key) throws Exception {
        // 生成一個可信任的隨機數源
        SecureRandom sr = new SecureRandom();

        // 從原始金鑰資料建立DESKeySpec物件
        DESKeySpec dks = new DESKeySpec(key);

        // 建立一個金鑰工廠，然後用它把DESKeySpec轉換成SecretKey物件
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        SecretKey securekey = keyFactory.generateSecret(dks);

        // Cipher物件實際完成解密操作
        Cipher cipher = Cipher.getInstance(DES);

        // 用金鑰初始化Cipher物件
        cipher.init(Cipher.DECRYPT_MODE, securekey, sr);

        return cipher.doFinal(data);
    }
}