使用ASP.Net加密Cookie[1]

Cookie是ASP.NET应用程序中很重要的一个全局变量，它可以用来保存用户登录信息、用户会话信息，以及一些全局变量或数据。为了提高应用程序的安全性，加密Cookie是很有必要的。本实例介绍在ASP.NET应用程序中加密Cookie的方法。

    本实例介绍如何使用在ASP.NET应用程序中的加密Cookie的方法。实例中采用的加密方法为DES和TripleDES两种方法，程序中均实现了DES和TripleDES的加密和解密方法，同时还设置了创建处理Cookie的类CookieEncrypt。

    1．创建新ASP.NET应用程序 

    在Visual Studio .NET 2003集成开发环境中创建新的ASP.NET Web应用程序，命名为Example_12_6。

    2．创建加密Cookie的类EncryptString

    在应用程序Example_12_6中添加类文件EncryptString.cs，该文件实现使用DES方法加密、解密数据和使用TripleDES方法加密、解密数据的方法，还定义了用来加密、解密的密钥Key以及IV。类文件 EncryptString.cs的程序代码如下：
    public class EncryptString
    {
    private static byte[] Key64 = {42, 16, 93, 156, 78, 4, 218, 32};
    private static byte[] IV64  = {55, 103, 246, 79, 36, 99, 167, 3};
    private static byte[] Key192 = {42, 16, 93, 156, 78, 4, 218, 32,15, 167,
    44,80, 26, 250, 155, 112,2, 94, 11, 204, 119, 35, 184, 197};
    private static byte[] IV192  = {55, 103, 246, 79, 36, 99, 167, 3,42,
    5, 62,83, 184, 7, 209, 13,145, 23, 200, 58, 173, 10, 121, 222};
    public static String Encrypt(String valueString)
    {
    if(valueString != "")
    {   //定义DES的Provider
    DESCryptoServiceProvider desprovider =
    new DESCryptoServiceProvider();
    //定义内存流
    MemoryStream memoryStream = new MemoryStream();
    //定义加密流
    CryptoStream cryptoStream = new CryptoStream(memoryStream,
    desprovider.CreateEncryptor(Key64,IV64),
    CryptoStreamMode.Write);
    //定义写IO流
    StreamWriter writerStream = new StreamWriter(cryptoStream);
    //写入加密后的字符流
    writerStream.Write(valueString);
    writerStream.Flush();
    cryptoStream.FlushFinalBlock();
    memoryStream.Flush();
    //返回加密后的字符串
    return(Convert.ToBase64String(memoryStream.GetBuffer(),0,
    (int)memoryStream.Length));
    }
    return(null);
    }
    public static String Decrypt(String valueString)
    {
    if(valueString != "")

 {   //定义DES的Provider
    DESCryptoServiceProvider desprovider =
    new DESCryptoServiceProvider();
    //转换解密的字符串为二进制
    byte[] buffer = Convert.FromBase64String(valueString);
    //定义内存流
    MemoryStream memoryStream = new MemoryStream();
    //定义加密流
    CryptoStream cryptoStream = new CryptoStream(memoryStream,
    desprovider.CreateEncryptor(Key64,IV64),
    CryptoStreamMode.Read);
    //定义读IO流
    StreamReader readerStream = new StreamReader(cryptoStream);
    //返回解密后的字符串
    return(readerStream.ReadToEnd());
    }
    return(null);
    }
    public static String EncryptTripleDES(String valueString)
    {
    if(valueString != "")
    {   //定义TripleDES的Provider
    TripleDESCryptoServiceProvider triprovider =
    new TripleDESCryptoServiceProvider();
    //定义内存流
    MemoryStream memoryStream = new MemoryStream();
    //定义加密流
    CryptoStream cryptoStream = new CryptoStream(memoryStream,
    triprovider.CreateEncryptor(Key192,IV192),
    CryptoStreamMode.Write);
    //定义写IO流
    StreamWriter writerStream = new StreamWriter(cryptoStream);
    //写入加密后的字符流
    writerStream.Write(valueString);
    writerStream.Flush();
    cryptoStream.FlushFinalBlock();
    memoryStream.Flush();
    //返回加密后的字符串
    return(Convert.ToBase64String(memoryStream.GetBuffer(),0,
    (int)memoryStream.Length));
    }
    return(null);
    }
    public static String DecryptTripleDES(String valueString)
    {
    if(valueString != "")
    {   //定义TripleDES的Provider
    TripleDESCryptoServiceProvider triprovider =
    new TripleDESCryptoServiceProvider();
    //转换解密的字符串为二进制
    byte[] buffer = Convert.FromBase64String(valueString);
    //定义内存流
    MemoryStream memoryStream = new MemoryStream();
    //定义加密流

CryptoStream cryptoStream = new CryptoStream(memoryStream,
    triprovider.CreateEncryptor(Key64,IV64),
    CryptoStreamMode.Read);
    //定义读IO流
    StreamReader readerStream = new StreamReader(cryptoStream);
    //返回解密后的字符串
    return(readerStream.ReadToEnd());
    }
    return(null);
    }
    }

    3．创建处理Cookie的类CookieEncrypt

    在应用程序Example_12_6中的类文件EncryptString.cs中添加类CookieEncrypt，该类用来处理应用程序的Cookie，如加密Cookie、获取Cookie、解密Cookie等。类CookieEncrypt的程序代码如下：
    public class CookieEncrypt
    {
    public static void SetCookie(HttpCookie cookie)
    {   //设置Cookie
    HttpContext.Current.Response.Cookies.Set(cookie);
    }
    public static void SetCookie(String key,String valueString)
    {   //设置加密后的Cookie
    key = HttpContext.Current.Server.UrlEncode(key);
    valueString = HttpContext.Current.Server.UrlEncode(valueString);
    HttpCookie cookie = new HttpCookie(key,valueString);
    SetCookie(cookie);
    }
    public static void SetCookie(String key,String valueString,
    DateTime expires)
    {   //设置加密后的Cookie，并设置Cookie的有效时间
    key = HttpContext.Current.Server.UrlEncode(key);
    valueString = HttpContext.Current.Server.UrlEncode(valueString);
    HttpCookie cookie = new HttpCookie(key,valueString);
    cookie.Expires = expires;
    SetCookie(cookie);
    }
    public static void SetTripleDESEncryptedCookie(String key,
    String valueString)
    {   //设置使用TripleDES加密后的Cookie
    key = EncryptString.EncryptTripleDES(key);
    valueString = EncryptString.EncryptTripleDES(valueString);
    SetCookie(key,valueString);
    }
    public static void SetTripleDESEncryptedCookie(String key,
    String valueString,DateTime expires)
    {   //设置使用TripleDES加密后的Cookie，并设置Cookie的有效时间
    key = EncryptString.EncryptTripleDES(key);
    valueString = EncryptString.EncryptTripleDES(valueString);
    SetCookie(key,valueString,expires);
    }

public static void SetEncryptedCookie(String key,String valueString)
    {   //设置使用DES加密后的Cookie
    key = EncryptString.Encrypt(key);
    valueString = EncryptString.Encrypt(valueString);
    SetCookie(key,valueString);
    }
    public static void SetEncryptedCookie(String key,
    String valueString,DateTime expires)
    {   //设置使用DES加密后的Cookie，并设置Cookie的有效时间
    key = EncryptString.Encrypt(key);
    valueString = EncryptString.Encrypt(valueString);
    SetCookie(key,valueString,expires);
    }
    public static String GetTripleDESEncryptedCookieValue(String key)
    {   //获取使用TripleDES解密后的Cookie
    key = EncryptString.EncryptTripleDES(key);
    String valueString = GetCookieValue(key);
    valueString = EncryptString.DecryptTripleDES(valueString);
    return(valueString);
    }
    public static String GetEncryptedCookieValue(String key)
    {   //获取使用DES解密后的Cookie
    key = EncryptString.Encrypt(key);
    String valueString = GetCookieValue(key);
    valueString = EncryptString.Decrypt(valueString);
    return(valueString);
    }
    public static HttpCookie GetCookie(String key)
    {   //通过关键字获取Cookie
    key = HttpContext.Current.Server.UrlEncode(key);
    return(HttpContext.Current.Request.Cookies.Get(key));
    }
    public static String GetCookieValue(String key)
    {   //通过关键字获取Cookie的value
    String valueString = GetCookie(key).Value;
    valueString = HttpContext.Current.Server.UrlDecode(valueString);
    return(valueString);
    }
    }

    4．设计页面EncryptCookies.aspx

    把应用程序Example_12_6的默认页面WebForm1.aspx重命名为 EncryptCookies.aspx，并在页面上添加3个Label控件，它们的名称分别为TripleDESCookie、 EncryptCookie和myCookie，分别用来显示使用TripleDES加密后的Cookie的值、使用DES加密后的Cookie的值和 Cookie的原始值。页面EncryptCookies.aspx的设计界面如图12-17所示。
    页面EncryptCookies.aspx的HTML设计代码如下：
    <asp:Label ID="myCookie" Runat="server"></asp:Label>
    <asp:Label ID="EncryptCookie" Runat="server"></asp:Label>
    <asp:Label ID="TripleDESCookie" Runat="server"></asp:Label>

 5．设计页面EncryptCookies.aspx

    页面EncryptCookies.aspx调用函数Page_Load(object sender, System.EventArgs e)初始化，该函数调用函数EncryptMyCookies()获取Cookie的原始值和加密后的值。函数Page_Load()和EncryptMyCookies()的程序代码如下：
    private void Page_Load(object sender, System.EventArgs e)
    {              //调用函数EncryptMyCookies()获取Cookie的原始值和加密后的值
    if(!Page.IsPostBack){EncryptMyCookies();}
    }
    private void EncryptMyCookies()
    {              //获取Cookie的原始值
    myCookie.Text =
    HttpContext.Current.Response.Cookies[HttpContext.Current.
    Response.Cookies.GetKey(0)].Value.ToString();
    //获取使用DES加密后Cookie的值
    EncryptCookie.Text = EncryptString.Encrypt(myCookie.Text);
    //获取使用TripleDES加密后Cookie的值
    TripleDESCookie.Text = EncryptString.EncryptTripleDES(myCookie.Text);
    }

    运行效果

    设置页面EncryptCookies.aspx为应用程序的起始页面。按F5键运行，出现如图12-18所示的初始界面。

图12-17  页面EncryptCookies.aspx的设计界面

 
图12-18  页面EncryptCookies.aspx的初始界面