package io.jpress.utils;
/**
 * Created by A007 on 2016/12/29.
 * 北京滔米科技有限公司 CloudPass项目
 */

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

/**
 * 解密
 */
public class MyDecryptUtils {
    /**
     * 对数据进行DES加密.
     * @param data 待进行DES加密的数据
     * @return 返回经过DES加密后的数据
     * @throws Exception
     * @author <a href="mailto:xiexingxing1121@126.com" mce_href="mailto:xiexingxing1121@126.com">AmigoXie</a>
     * Creation date: 2007-7-31 - 下午12:06:24
     */
    public final static String decrypt(String data) throws Exception {
        return new String(decrypt(hex2byte(data.getBytes()),"kEHrDooxWHCWtfeSxvDvgqZq".getBytes()));
    }


    private static byte[] decrypt(byte[] data, byte[] key) throws Exception {
        // DES算法要求有一个可信任的随机数源
        SecureRandom sr = new SecureRandom();
        // 从原始密匙数据创建一个DESKeySpec对象
        DESKeySpec dks = new DESKeySpec(key);
        // 创建一个密匙工厂，然后用它把DESKeySpec对象转换成
        // 一个SecretKey对象
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
        SecretKey securekey = keyFactory.generateSecret(dks);
        // 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, sr);
        // 现在，获取数据并解密
        // 正式执行解密操作
        return cipher.doFinal(data);
    }
    public static byte[] hex2byte(byte[] b) {
        if ((b.length % 2) != 0)
            throw new IllegalArgumentException("长度不是偶数");
        byte[] b2 = new byte[b.length / 2];
        for (int n = 0; n < b.length; n += 2) {
            String item = new String(b, n, 2);
            b2[n / 2] = (byte) Integer.parseInt(item, 16);
        }
        return b2;
    }


}