package com.anyun.exam.lib.util;

import android.util.Base64;

import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;

public class DESUtil {
    private static String password = "safeluck";

    /**
     *
     * @Method: encrypt
     * @Description: 加密数据
     * @param data
     * @return
     * @throws Exception
     * @date 2016年7月26日
     */
    public static String encrypt(String data, String pwd) {  //对string进行BASE64Encoder转换
        byte[] bt = encryptByKey(data.getBytes(), pwd);
        return Base64.encodeToString(bt, Base64.DEFAULT);
    }

    public static byte[] encrypt(byte[] message, String key) throws Exception {
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF-8"));
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        SecretKey secretKey = keyFactory.generateSecret(desKeySpec);
        IvParameterSpec iv = new IvParameterSpec(key.getBytes("UTF-8"));
        cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);
        return cipher.doFinal(message);
    }

    public static byte[] encrypt(byte[] message, byte[] key) throws Exception {
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        DESKeySpec desKeySpec = new DESKeySpec(key);
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        SecretKey secretKey = keyFactory.generateSecret(desKeySpec);
        IvParameterSpec iv = new IvParameterSpec(key);
        cipher.init(Cipher.ENCRYPT_MODE, secretKey, iv);
        return cipher.doFinal(message);
    }

    public static byte[] decrypt2(byte[] message, String key) throws Exception {
        Cipher cipher = Cipher.getInstance("DES/CBC/PKCS5Padding");
        DESKeySpec desKeySpec = new DESKeySpec(key.getBytes("UTF-8"));
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        SecretKey secretKey = keyFactory.generateSecret(desKeySpec);
        IvParameterSpec iv = new IvParameterSpec(key.getBytes("UTF-8"));
        cipher.init(Cipher.DECRYPT_MODE, secretKey, iv);
        return cipher.doFinal(message);
    }

    /**
     *
     * @Method: encrypt
     * @Description: 解密数据
     * @param data
     * @return
     * @throws Exception
     * @date 2016年7月26日
     */
    public static String decryptor(String data, String pwd) throws Exception {  //对string进行BASE64Encoder转换
        byte[] bt = decrypt(Base64.decode(data, Base64.DEFAULT), pwd);
        String strs = new String(bt);
        return strs;
    }
    /**
     * 加密
     * @param datasource byte[]
     * @param password String
     * @return byte[]
     */
    private static byte[] encryptByKey(byte[] datasource, String key) {
        try{
            SecureRandom random = new SecureRandom();

            DESKeySpec desKey = new DESKeySpec(key.getBytes());
            //创建一个密匙工厂，然后用它把DESKeySpec转换成
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            SecretKey securekey = keyFactory.generateSecret(desKey);
            //Cipher对象实际完成加密操作
            Cipher cipher = Cipher.getInstance("DES");
            //用密匙初始化Cipher对象
            cipher.init(Cipher.ENCRYPT_MODE, securekey);
            //现在，获取数据并加密
            //正式执行加密操作
            return cipher.doFinal(datasource);
        }catch(Throwable e){
            e.printStackTrace();
        }
        return null;
    }
    /**
     * 解密
     * @param src byte[]
     * @param password String
     * @return byte[]
     * @throws Exception
     */
    private static byte[] decrypt(byte[] src, String key) throws Exception {
        // DES算法要求有一个可信任的随机数源
        SecureRandom random = new SecureRandom();
        // 创建一个DESKeySpec对象
        DESKeySpec desKey = new DESKeySpec(key.getBytes());
        // 创建一个密匙工厂
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        // 将DESKeySpec对象转换成SecretKey对象
        SecretKey securekey = keyFactory.generateSecret(desKey);
        // Cipher对象实际完成解密操作
        Cipher cipher = Cipher.getInstance("DES");
        // 用密匙初始化Cipher对象
        cipher.init(Cipher.DECRYPT_MODE, securekey, random);
        // 真正开始解密操作
        return cipher.doFinal(src);
    }
}