url加密解密的一个cs类

网上很多人在问怎么实现Web系统URL传输(表单提交)参数加密。例如:要进行一个用户帐号编辑，要传递用户的ID，URL如下:http://localhost/mysystem/editAccounts.aspx?ID=2 
但又不想让别人知道这个用户的ID为2，恶意的使用者可能还会将2修改，改为别的用户ID。  

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

namespace EIP.Framework 
...{ 
public class Security 
...{ 
string _QueryStringKey = "abcdefgh"; //URL传输参数加密Key 
string _PassWordKey = "hgfedcba"; //PassWord加密Key 

public Security() 
...{ 
} 

public string EncryptQueryString(string QueryString) 
...{ 
return Encrypt(QueryString,_QueryStringKey); 
} 


public string DecryptQueryString(string QueryString) 
...{ 
return Decrypt(QueryString,_QueryStringKey); 
} 


public string EncryptPassWord(string PassWord) 
...{ 
return Encrypt(PassWord,_PassWordKey); 
} 


public string DecryptPassWord(string PassWord) 
...{ 
return Decrypt(PassWord,_PassWordKey); 
} 

/**////  
/// DEC 加密过程 
///  
///  
///  
///
public string Encrypt(string pToEncrypt,string sKey)  
...{  
DESCryptoServiceProvider des = new DESCryptoServiceProvider(); //把字符串放到byte数组中  

byte[] inputByteArray = Encoding.Default.GetBytes(pToEncrypt);  
//byte[] inputByteArray=Encoding.Unicode.GetBytes(pToEncrypt);  

des.Key = ASCIIEncoding.ASCII.GetBytes(sKey); //建立加密对象的密钥和偏移量 
des.IV = ASCIIEncoding.ASCII.GetBytes(sKey); //原文使用ASCIIEncoding.ASCII方法的GetBytes方法  
MemoryStream ms = new MemoryStream(); //使得输入密码必须输入英文文本 
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();  
}  

/**////  
/// DEC 解密过程 
///  
///  
///  
///
public 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); //建立加密对象的密钥和偏移量，此值重要，不能修改  
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(); //建立StringBuild对象，CreateDecrypt使用的是流对象，必须把解密后的文本变成流对象  

return System.Text.Encoding.Default.GetString(ms.ToArray());  
}  

/**////  
/// 检查己加密的字符串是否与原文相同 
///  
///  
///  
///  
///
public bool ValidateString(string EnString, string FoString, int Mode) 
...{ 
switch (Mode) 
...{ 
default: 
case 1: 
if (Decrypt(EnString,_QueryStringKey) == FoString.ToString()) 
...{ 
return true; 
} 
else 
...{ 
return false; 
} 
case 2: 
if (Decrypt(EnString,_PassWordKey) == FoString.ToString()) 
...{ 
return true; 
} 
else 
...{ 
return false; 
} 
} 
} 
} 
}