package com.albedo.security;

import javax.crypto.Cipher;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;
import javax.crypto.spec.IvParameterSpec;
import java.security.Key;
import java.security.SecureRandom;
import java.util.Base64;

/**
 * des 加解密實現
 */
public class DESUtil {
    
 
//字元編碼
    public static final String CHARSET_UTF8 = "UTF-8";
    //加密演算法DES
    public static final String DES = "DES";
    //電話本模式
    public static final String DES_ECB = "DES/ECB/PKCS5Padding";
    //加密塊鏈模式--推薦
    public static final String DES_CBC = "DES/CBC/PKCS5Padding";


    /**
     * 生成key
     *
     * 
 
@param password
     * @return
     * @throws Exception
     */
    private static Key generateKey(String password) throws Exception {
        DESKeySpec dks = new DESKeySpec(password.getBytes(CHARSET_UTF8));
        SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
        return keyFactory.generateSecret(dks);
    }
    
 
/**
     * DES加密字串--ECB格式
     *
     * @param password 加密密碼，長度不能夠小於8位
     * @param data     待加密字串
     * @return 加密後內容
     */
    public static String encryptECB(String password, String data) {
        if (password == null || password.length() < 8) {
            throw new RuntimeException("加密失敗，key不能小於8位");
        }
        if (data == null) {
            return null;
        }
        try {
            Key secretKey = generateKey(password);
            Cipher cipher = Cipher.getInstance(DES_ECB);
            cipher.init(Cipher.ENCRYPT_MODE, secretKey, new SecureRandom());
            byte[] bytes = cipher.doFinal(data.getBytes(CHARSET_UTF8));
            //JDK1.8及以上可直接使用Base64，JDK1.7及以下可以使用BASE64Encoder
            return new String(Base64.getEncoder().encode(bytes));

        } catch (Exception e) {
            e.printStackTrace();
            return data;
        }
    }

    /**
     * DES解密字串--ECB格式
     *
     * @param password 解密密碼，長度不能夠小於8位
     * @param data     待解密字串
     * @return 解密後內容
     */
    public static String decryptECB(String password, String data) throws Exception {
        Key secretKey = generateKey(password);
        Cipher cipher = Cipher.getInstance(DES_ECB);
        cipher.init(Cipher.DECRYPT_MODE, secretKey, new SecureRandom());
        return new String(cipher.doFinal(Base64.getDecoder().decode(data.getBytes(CHARSET_UTF8))), CHARSET_UTF8);

    }
    /**
     * DES加密字串-CBC加密格式
     *
     * @param password 加密密碼，長度不能夠小於8位
     * @param data     待加密字串
     * @return 加密後內容
     */
    public static String encryptCBC(String password, String data) {
        if (password == null || password.length() < 8) {
            throw new RuntimeException("加密失敗，key不能小於8位");
        }
        if (data == null) {
            return null;
        }
        try {
            Key secretKey = generateKey(password);
            Cipher cipher = Cipher.getInstance(DES_CBC);
            IvParameterSpec spec=new IvParameterSpec("12345678".getBytes(CHARSET_UTF8));
            cipher.init(Cipher.ENCRYPT_MODE, secretKey, spec);
            byte[] bytes = cipher.doFinal(data.getBytes(CHARSET_UTF8));
            //JDK1.8及以上可直接使用Base64，JDK1.7及以下可以使用BASE64Encoder
            return new String(Base64.getEncoder().encode(bytes));

        } catch (Exception e) {
            e.printStackTrace();
            return data;
        }
    }

    /**
     * DES解密字串--CBC格式
     *
     * @param password 解密密碼，長度不能夠小於8位
     * @param data     待解密字串
     * @return 解密後內容
     */
    public static String decryptCBC(String password, String data) throws Exception {
        Key secretKey = generateKey(password);
        Cipher cipher = Cipher.getInstance(DES_CBC);
        IvParameterSpec spec=new IvParameterSpec("12345679".getBytes(CHARSET_UTF8));
        cipher.init(Cipher.DECRYPT_MODE, secretKey, spec);
        return new String(cipher.doFinal(Base64.getDecoder().decode(data.getBytes(CHARSET_UTF8))), CHARSET_UTF8);

    }

}