package com.utils;

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

/**
 * DES加密解密类.
 */
public class DESTools {
    /**
     * 加密、解密key，用作生成二维码之用，无其他用途。
     */
    private static final String PASSWORD_CRYPT_KEY = "HhiTuqm7lsMVHYD4Bkj2B5jSUh0IKPNk";

    private final static String ALGORITHM = "DES";

    public static void main(String[] args) throws Exception {
        String orgStr = "202cb962ac59075b964b07152d234b70";
        long start = System.currentTimeMillis();
        for (int i = 0; i < 1000; i++) {
            orgStr = DESTools.getRandomString(20);
            String encrptStr = DESTools.encrypt(orgStr);
            String decrptStr = DESTools.decrypt(encrptStr);
            if (!orgStr.equals(decrptStr)) {
                System.out.println("error!!");
            }
        }
        long end = System.currentTimeMillis();
        System.out.println("time:" + (end - start));

    }

    /**
     * 生成随机字符串
     *
     * @param length
     * @return
     */
    public static String getRandomString(int length) { //length表示生成字符串的长度
        String base = "abcdefghijklmnopqrstuvwxyz0123456789";
        Random random = new Random();
        StringBuffer sb = new StringBuffer();
        for (int i = 0; i < length; i++) {
            int number = random.nextInt(base.length());
            sb.append(base.charAt(number));
        }
        return sb.toString();
    }

    /**
     * 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()),
                PASSWORD_CRYPT_KEY.getBytes()));
    }

    /**
     * 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, String key) throws Exception {
        return new String(decrypt(hex2byte(data.getBytes()),
                key.getBytes()));
    }

    /**
     * 对用DES加密过的数据进行解密.
     *
     * @param data DES加密数据
     * @return 返回解密后的数据
     * @throws Exception
     * @author <a href="mailto:xiexingxing1121@126.com" mce_href="mailto:xiexingxing1121@126.com">AmigoXie</a>
     * Creation date: 2007-7-31 - 下午12:07:54
     */
    public final static String encrypt(String data) throws Exception {
        return byte2hex(encrypt(data.getBytes(), PASSWORD_CRYPT_KEY
                .getBytes()));
    }


    /**
     * 对用DES加密过的数据进行解密.
     *
     * @param data DES加密数据
     * @return 返回解密后的数据
     * @throws Exception
     * @author <a href="mailto:xiexingxing1121@126.com" mce_href="mailto:xiexingxing1121@126.com">AmigoXie</a>
     * Creation date: 2007-7-31 - 下午12:07:54
     */
    public final static String encrypt(String data, String key) throws Exception {
        return byte2hex(encrypt(data.getBytes(), key
                .getBytes()));
    }


    /**
     * 用指定的key对数据进行DES加密.
     *
     * @param data 待加密的数据
     * @param key  DES加密的key
     * @return 返回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12:09:03
     */
    private static byte[] encrypt(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DESKeySpec对象  
        DESKeySpec dks = new DESKeySpec(key);
        // 创建一个密匙工厂，然后用它把DESKeySpec转换成  
        // 一个SecretKey对象  
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(ALGORITHM);
        SecretKey securekey = keyFactory.generateSecret(dks);
        // Cipher对象实际完成加密操作  
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        // 用密匙初始化Cipher对象  
        cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
        // 现在，获取数据并加密  
        // 正式执行加密操作  
        return cipher.doFinal(data);
    }

    /**
     * 用指定的key对数据进行DES解密.
     *
     * @param data 待解密的数据
     * @param key  DES解密的key
     * @return 返回DES解密后的数据
     * @throws Exception
     * @author <a href="mailto:xiexingxing1121@126.com" mce_href="mailto:xiexingxing1121@126.com">AmigoXie</a>
     * Creation date: 2007-7-31 - 下午12:10:34
     */
    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(ALGORITHM);
        SecretKey securekey = keyFactory.generateSecret(dks);
        // Cipher对象实际完成解密操作  
        Cipher cipher = Cipher.getInstance(ALGORITHM);
        // 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;
    }

    public static String byte2hex(byte[] b) {
        String hs = "";
        String stmp = "";
        for (int n = 0; n < b.length; n++) {
            stmp = (Integer.toHexString(b[n] & 0XFF));
            if (stmp.length() == 1)
                hs = hs + "0" + stmp;
            else
                hs = hs + stmp;
        }
        return hs.toUpperCase();
    }
}