C#实现Des加密和解密

using System;
using System.IO;
using System.Text;
using System.Security.Cryptography;

namespace Common
{
    /**//// <summary>
    /// Summary description for Security.
    /// </summary>
    public class Security
    {
        public Security()
        {
            //
            // TODO: Add constructor logic here
            //
        }

        /**//// <summary>
        /// 加密
        /// </summary>
        /// <param name="pToEncrypt">要加密的字符串</param>
        /// <param name="sKey">密匙</param>
        /// <returns>加密后字符串</returns>
        public static string  Encrypt(string pToEncrypt,string sKey)  
        {  
            DESCryptoServiceProvider  des  =  new  DESCryptoServiceProvider();  
            byte[]  inputByteArray  =  Encoding.Default.GetBytes(pToEncrypt);
            des.Key  =  ASCIIEncoding.ASCII.GetBytes(sKey);  
            des.IV  =  ASCIIEncoding.ASCII.GetBytes(sKey);  
            MemoryStream  ms  =  new  MemoryStream();  
            CryptoStream  cs  =  new  CryptoStream(ms,des.CreateEncryptor(),CryptoStreamMode.Write);  
            cs.Write(inputByteArray,0,inputByteArray.Length);  
            cs.FlushFinalBlock();  
            StringBuilder  ret  =  new  StringBuilder();  
            foreach(byte  b  in  ms.ToArray())  
            {  
                ret.AppendFormat("{0:X2}",  b);  
            }  
            ret.ToString();  
            return  ret.ToString();  
        }  

        /**//// <summary>
        /// 解密
        /// </summary>
        /// <param name="pToDecrypt">要解密的字符串</param>
        /// <param name="sKey">密匙</param>
        /// <returns>解密后字符串</returns>
        public static string  Decrypt(string pToDecrypt,string sKey)  
        {  
            DESCryptoServiceProvider  des  =  new  DESCryptoServiceProvider(); 
            byte[]  inputByteArray  =  new  byte[pToDecrypt.Length  /  2];  
            for(int  x  =  0;  x  <  pToDecrypt.Length  /  2;  x++)  
            {  
                int  i  =  (Convert.ToInt32(pToDecrypt.Substring(x* 2,2),16));  
                inputByteArray[x]  =  (byte)i;  
            }   
            des.Key  =  ASCIIEncoding.ASCII.GetBytes(sKey);  
            des.IV  =  ASCIIEncoding.ASCII.GetBytes(sKey);  
            MemoryStream  ms  =  new  MemoryStream();  
            CryptoStream  cs  =  new  CryptoStream(ms,  des.CreateDecryptor(),CryptoStreamMode.Write); 
            cs.Write(inputByteArray,  0,  inputByteArray.Length);  
            cs.FlushFinalBlock();
            StringBuilder  ret  =  new  StringBuilder();               
            return  System.Text.Encoding.Default.GetString(ms.ToArray());  
        }
    }
}