using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Security.Cryptography;
using System.IO;
 
namespace ConsoleApplication1
{
    class Program
    {
        static string encryptKey = "Oyea";    //定义密钥
 
        #region 加密字符串
        /// /// 加密字符串
        /// www.
        /// 要加密的字符串
        /// 加密后的字符串
        static string Encrypt(string str)
        { 
            DESCryptoServiceProvider descsp = new DESCryptoServiceProvider();   //实例化加/解密类对象
  
            byte[] key = Encoding.Unicode.GetBytes(encryptKey); //定义字节数组，用来存储密钥 
 
            byte[] data = Encoding.Unicode.GetBytes(str);//定义字节数组，用来存储要加密的字符串
   
            MemoryStream MStream = new MemoryStream(); //实例化内存流对象   
 
            //使用内存流实例化加密流对象
            CryptoStream CStream = new CryptoStream(MStream, descsp.CreateEncryptor(key, key), CryptoStreamMode.Write);  
 
            CStream.Write(data, 0, data.Length);  //向加密流中写入数据   
 
            CStream.FlushFinalBlock();              //释放加密流   
 
            return Convert.ToBase64String(MStream.ToArray());//返回加密后的字符串
        }
        #endregion
 
        #region 解密字符串
        ///
        /// 解密字符串
        ///
        /// 要解密的字符串
        /// 解密后的字符串
        static string Decrypt(string str)
        {   
            DESCryptoServiceProvider descsp = new DESCryptoServiceProvider();   //实例化加/解密类对象 
   
            byte[] key = Encoding.Unicode.GetBytes(encryptKey); //定义字节数组，用来存储密钥 
  
            byte[] data = Convert.FromBase64String(str);//定义字节数组，用来存储要解密的字符串
    
            MemoryStream MStream = new MemoryStream(); //实例化内存流对象   
 
            //使用内存流实例化解密流对象    
            CryptoStream CStream = new CryptoStream(MStream, descsp.CreateDecryptor(key, key), CryptoStreamMode.Write);
 
            CStream.Write(data, 0, data.Length);      //向解密流中写入数据  
 
            CStream.FlushFinalBlock();               //释放解密流   
 
            return Encoding.Unicode.GetString(MStream.ToArray());       //返回解密后的字符串
        }
        #endregion
 
        static void Main(string[] args)
        {
            Console.Write("请输入要加密的字符串：");   //提示输入字符串   
            Console.WriteLine();                  //换行输入
            string str = Console.ReadLine();     //记录输入的字符串   
            string strNew = Encrypt(str);              //加密字符串   
            Console.WriteLine("加密后的字符串：" + strNew);  //输出加密后的字符串   
            Console.WriteLine("解密后的字符串：" + Decrypt(strNew)); //解密字符串并输出  
            Console.ReadLine();
        }
    }
}