How to Encrypt and Decrypt the Query string automatically by C#, Asp.Net

Just Create a Businesslogic class in App_code folder with the name QueryStringModule.cs
and then add the below given code.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Security.Cryptography;
using System.Text;
using System.IO;

/// 

/// Summary description for QueryStringModule
/// 
public class QueryStringModule : IHttpModule
{
    /// 
  
    /// Summary description for QueryStringModule  
    /// 
  
    
        //  private ILog m_Logger = LogManager.GetLogger(typeof(QueryStringModule));  
        #region IHttpModule Members

        public void Dispose()
        {
            // Nothing to dispose  
        }

        public void Init(HttpApplication context)
        {
            context.BeginRequest += new EventHandler(context_BeginRequest);
        }

        #endregion

        private const string PARAMETER_NAME = "enc=";
        private const string ENCRYPTION_KEY = "key";

        void context_BeginRequest(object sender, EventArgs e)
        {
            HttpContext context = HttpContext.Current;
            string query = string.Empty;
            string path = string.Empty;

            try
            {
                if (context.Request.Url.OriginalString.Contains("aspx") && context.Request.RawUrl.Contains("?"))
                {
                    query = ExtractQuery(context.Request.RawUrl);
                    path = GetVirtualPath();

                    if (query.StartsWith(PARAMETER_NAME, StringComparison.OrdinalIgnoreCase))
                    {
                        // Decrypts the query string and rewrites the path.  
                        string rawQuery = query.Replace(PARAMETER_NAME, string.Empty);
                        string decryptedQuery = Decrypt(rawQuery);
                        context.RewritePath(path, string.Empty, decryptedQuery);
                    }
                    else if (context.Request.HttpMethod == "GET")
                    {
                        // Encrypt the query string and redirects to the encrypted URL.  
                        // Remove if you don't want all query strings to be encrypted automatically.  
                        string encryptedQuery = Encrypt(query);
                        context.Response.Redirect(path + encryptedQuery, false);
                    }
                }
            }
            catch (Exception ex)
            {
                // m_Logger.Error("An error occurred while parsing the query string in the URL: " + path, ex);  
                context.Response.Redirect("~/Home.aspx");
            }

        }

        /// 
  
        /// Parses the current URL and extracts the virtual path without query string.  
        /// 
  
        /// The virtual path of the current URL.  
        private static string GetVirtualPath()
        {
            string path = HttpContext.Current.Request.RawUrl;
            path = path.Substring(0, path.IndexOf("?"));
            path = path.Substring(path.LastIndexOf("/") + 1);
            return path;
        }

        /// 
  
        /// Parses a URL and returns the query string.  
        /// 
  
        /// The URL to parse./// The query string without the question mark.  
        private static string ExtractQuery(string url)
        {
            int index = url.IndexOf("?") + 1;
            return url.Substring(index);
        }

        #region Encryption/decryption

        /// 
  
        /// The salt value used to strengthen the encryption.  
        /// 
  
        private readonly static byte[] SALT = Encoding.ASCII.GetBytes(ENCRYPTION_KEY.Length.ToString());

        /// 
  
        /// Encrypts any string using the Rijndael algorithm.  
        /// 
  
        /// The string to encrypt./// A Base64 encrypted string.  
        private static string Encrypt(string inputText)
        {
            RijndaelManaged rijndaelCipher = new RijndaelManaged();
            byte[] plainText = Encoding.Unicode.GetBytes(inputText);
            PasswordDeriveBytes SecretKey = new PasswordDeriveBytes(ENCRYPTION_KEY, SALT);

            using (ICryptoTransform encryptor = rijndaelCipher.CreateEncryptor(SecretKey.GetBytes(32), SecretKey.GetBytes(16)))
            {
                using (MemoryStream memoryStream = new MemoryStream())
                {
                    using (CryptoStream cryptoStream = new CryptoStream(memoryStream, encryptor, CryptoStreamMode.Write))
                    {
                        cryptoStream.Write(plainText, 0, plainText.Length);
                        cryptoStream.FlushFinalBlock();
                        return "?" + PARAMETER_NAME + Convert.ToBase64String(memoryStream.ToArray());
                    }
                }
            }
        }

        /// 
  
        /// Decrypts a previously encrypted string.  
        /// 
  
        /// The encrypted string to decrypt./// A decrypted string.  
        private static string Decrypt(string inputText)
        {
            RijndaelManaged rijndaelCipher = new RijndaelManaged();

            byte[] encryptedData = Convert.FromBase64String(inputText);
            PasswordDeriveBytes secretKey = new PasswordDeriveBytes(ENCRYPTION_KEY, SALT);

            using (ICryptoTransform decryptor = rijndaelCipher.CreateDecryptor(secretKey.GetBytes(32), secretKey.GetBytes(16)))
            {
                using (MemoryStream memoryStream = new MemoryStream(encryptedData))
                {
                    using (CryptoStream cryptoStream = new CryptoStream(memoryStream, decryptor, CryptoStreamMode.Read))
                    {
                        byte[] plainText = new byte[encryptedData.Length];
                        int decryptedCount = cryptoStream.Read(plainText, 0, plainText.Length);
                        return Encoding.Unicode.GetString(plainText, 0, decryptedCount);
                    }
                }
            }
        }

        #endregion

    }

After then in web.config file add this code...

Thats it, now get the Querystring on any page in encripted manner,
For example:

LblQuery.Text=Request.QueryString["id"].ToString();