/*
 * Copyright  2017 [AllenCoder]
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.allen.apputils;


import java.io.UnsupportedEncodingException;
import java.security.NoSuchAlgorithmException;
import javax.crypto.Cipher;
import javax.crypto.NoSuchPaddingException;
import javax.crypto.SecretKey;
import javax.crypto.spec.SecretKeySpec;

/**
 * 3DES 加密/解密
 */




/**
 * SecretUtils {3DES加密解密的工具类 }

 */
public class SecretUtils {

    //定义加密算法，有DES、DESede(即3DES)、Blowfish
    private static final String Algorithm = "DESede";
    private static final String PASSWORD_CRYPT_KEY = "2017abcdefghijklmnopQrst123";


    /**
     * 加密方法
     * @param src 源数据的字节数组
     * @return
     */
    public static byte[] encryptMode(byte[] src) {
        try {
            SecretKey deskey = new SecretKeySpec(build3DesKey(PASSWORD_CRYPT_KEY), Algorithm);    //生成密钥
            Cipher c1 = Cipher.getInstance(Algorithm);    //实例化负责加密/解密的Cipher工具类
            c1.init(Cipher.ENCRYPT_MODE, deskey);    //初始化为加密模式
            return c1.doFinal(src);
        } catch (java.security.NoSuchAlgorithmException e1) {
            e1.printStackTrace();
        } catch (javax.crypto.NoSuchPaddingException e2) {
            e2.printStackTrace();
        } catch (java.lang.Exception e3) {
            e3.printStackTrace();
        }
        return null;
    }


    /**
     * 解密函数
     * @param src 密文的字节数组
     * @return
     */
    public static byte[] decryptMode(byte[] src) {
        try {
            SecretKey deskey = new SecretKeySpec(build3DesKey(PASSWORD_CRYPT_KEY), Algorithm);
            Cipher c1 = Cipher.getInstance(Algorithm);
            c1.init(Cipher.DECRYPT_MODE, deskey);    //初始化为解密模式
            return c1.doFinal(src);
        } catch (java.security.NoSuchAlgorithmException e1) {
            e1.printStackTrace();
        } catch (javax.crypto.NoSuchPaddingException e2) {
            e2.printStackTrace();
        } catch (java.lang.Exception e3) {
            e3.printStackTrace();
        }
        return null;
    }


    /*
     * 根据字符串生成密钥字节数组
     * @param keyStr 密钥字符串
     * @return
     * @throws UnsupportedEncodingException
     */
    public static byte[] build3DesKey(String keyStr) throws UnsupportedEncodingException{
        byte[] key = new byte[24];    //声明一个24位的字节数组，默认里面都是0
        byte[] temp = keyStr.getBytes("UTF-8");    //将字符串转成字节数组

        /*
         * 执行数组拷贝
         * System.arraycopy(源数组，从源数组哪里开始拷贝，目标数组，拷贝多少位)
         */
        if(key.length > temp.length){
            //如果temp不够24位，则拷贝temp数组整个长度的内容到key数组中
            System.arraycopy(temp, 0, key, 0, temp.length);
        }else{
            //如果temp大于24位，则拷贝temp数组24个长度的内容到key数组中
            System.arraycopy(temp, 0, key, 0, key.length);
        }
        return key;
    }
}