/**
 * Created by lenovo on 2016/12/13.
 * DES加解密
 */
public class DESUtils
{
    
    /**
     * DES金鑰
     */
    private static String key = "secray.0n.www";
    
    /**
     * DES加密
     * @param data:需要加密的資料
     * @return
     */
    public static String encryptDES(String data) throws Exception
    {
        String s = null;
        if ( data != null )
        {
            //DES演算法要求有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 desKeySpec = new DESKeySpec(key.getBytes());
            //建立一個金鑰工廠，用它將DESKeySpec轉化成SecretKey物件
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            SecretKey securekey = keyFactory.generateSecret(desKeySpec);
            //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);
            //將加密後的資料編碼成字串
            Base64Utils base64Utils = new Base64Utils();
            s = base64Utils.encode(cipher.doFinal(data.getBytes()));
        }
        return s;
    }
    
    /**
     * DES解密
     * @param data:需要解密的資料
     * @return
     * @throws Exception
     */
    public static String decryptDES(String data) throws Exception
    {
        String s = null;
        if ( data != null )
        {
            //DES演算法要求有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 desKeySpec = new DESKeySpec(key.getBytes());
            //建立一個金鑰工廠，用它將DESKeySpec轉化成SecretKey物件
            SecretKeyFactory keyFactory = SecretKeyFactory.getInstance("DES");
            SecretKey securekey = keyFactory.generateSecret(desKeySpec);
            //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);
            //將加密後的資料解碼再解密
            Base64Utils base64Utils = new Base64Utils();
            byte[] buf = cipher.doFinal(base64Utils.decode(data));
            s = new String(buf);
        }
        return s;
    }
    
    public static void main(String[] args)
    {
        String data = "123";
        //加密
        try
        {
            String str1 = encryptDES(data);
            System.out.println("加密後為:str1=" + str1);
            //解密
            String str2 = decryptDES(str1);
            System.out.println("解密後為:str2=" + str2);
        }
        catch (Exception e)
        {
            e.printStackTrace();
        }
        
    }
}