先写入一个cookie；

public static void SetCookie(string name, string value, int day)
{
name = Encrypt(name,"ToCookie");
value = Encrypt(value, "ToCookie");
HttpCookie cookie = new HttpCookie(name, value);
cookie.Expires = DateTime.Now.AddDays(day);
//判断是否存在，如果不存在就创建
if (HttpContext.Current.Request.Cookies[name] == null)
{
HttpContext.Current.Response.SetCookie(cookie);
}
}

然后读取一个cookie：

public string GetCookie(string cookie)
{
cookie = CookieManager.Encrypt(cookie, "ToCookie");

//判断是否存在
if (Request.Cookies[cookie] != null)
{

return CookieManager.Decrypt(Request.Cookies[cookie].Value.ToString(), "ToCookie");
}
else
{
return "";
}
}

cookie肯定也要加密

#region DEC 加密过程

/// <summary>

/// 加密

/// </summary>

/// <param name="pToEncrypt"></param>

/// <param name="sKey"></param>

/// <returns></returns>

public static 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();

}

#endregion

#region  DEC 解密过程

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);　//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());

}

///其中的sKey非常重要,定义的时候定义成string然后赋值等于八个字母或数字,注意,必须8个

///这个也很实用,譬如你想进入文章页面,传入的参数的aid=10000

///这时把10000给加密

///然后接受的时候解密.这样能有效的防止sql注入攻击!!!?????

#endregion