Encrypting Querystring Parameters

I implemented some routines to encrypt/decrypt a querystring parameter using a symmetric key over Base64. This is based off the following article:

http://devcity.net/Articles/47/1/encrypt_querystring.aspx

Below are the specific places where this was implemented.

1. Namespace: Something.Data
   
   using System;
   using System.Collections.Generic;
   using System.IO;
   using System.Text;
   using System.Security.Cryptography;
   
   namespace Something.Web
   {
   public class Encryption64
   {
   //private byte[] key = {};
   //private byte[] IV = {10, 20, 30, 40, 50, 60, 70, 80}; // it can be any byte value
   public string Decrypt(string stringToDecrypt, string sEncryptionKey)
   {
   byte[] key = { };
   byte[] IV = { 10, 20, 30, 40, 50, 60, 70, 80 };
   byte[] inputByteArray = new byte[stringToDecrypt.Length];
   try
   {
   key = Encoding.UTF8.GetBytes(sEncryptionKey.Substring(0, 8));
   DESCryptoServiceProvider des = new DESCryptoServiceProvider();
   inputByteArray = Convert.FromBase64String(stringToDecrypt);
   MemoryStream ms = new MemoryStream();
   CryptoStream cs = new CryptoStream(ms, des.CreateDecryptor(key, IV), CryptoStreamMode.Write);
   cs.Write(inputByteArray, 0, inputByteArray.Length);
   cs.FlushFinalBlock();
   Encoding encoding = Encoding.UTF8;
   return encoding.GetString(ms.ToArray());
   }
   catch (System.Exception ex)
   {
   throw ex;
   }
   }
   public string Encrypt(string stringToEncrypt, string sEncryptionKey)
   {
   byte[] key = { };
   byte[] IV = { 10, 20, 30, 40, 50, 60, 70, 80 };
   byte[] inputByteArray; //Convert.ToByte(stringToEncrypt.Length)
   try
   {
   key = Encoding.UTF8.GetBytes(sEncryptionKey.Substring(0, 8));
   DESCryptoServiceProvider des = new DESCryptoServiceProvider();
   inputByteArray = Encoding.UTF8.GetBytes(stringToEncrypt);
   MemoryStream ms = new MemoryStream();
   CryptoStream cs = new CryptoStream(ms, des.CreateEncryptor(key, IV), CryptoStreamMode.Write);
   cs.Write(inputByteArray, 0, inputByteArray.Length);
   cs.FlushFinalBlock();
   return Convert.ToBase64String(ms.ToArray());
   }
   catch (System.Exception ex)
   {
   throw ex;
   }
   }
   }
   }
   
   
2. Something.Common.SessionConst class (complied into its own Dll)
   
   public const string IAteByte = "!#$a54?3";
   
   
3. SomethingWebsite.App_Code.QuerystringProtect.cs
   
   using System;
   using System.Web;
   using Immunization.Common;
   using Immunization.Web;
   ///
   
   /// Summary description for QuerystringProtect
   ///
   
   public static class QuerystringProtect
   {
   public static string EncryptQueryString(string strQueryString)
   {
   Encryption64 e64 = new Encryption64();
   return e64.Encrypt(strQueryString, SessionConst.IAteByte);
   }
   public static string DecryptQueryString(string strQueryString)
   {
   Encryption64 e64 = new Encryption64();
   return e64.Decrypt(strQueryString, SessionConst.IAteByte);
   }
   }
   
   
4. Encrypt querystring in URL - ASPX code-behind:
   
   btnDoc.NavigateUrl += QuerystringProtect.EncryptQueryString(someObject.objectId.ToString());
   
   
5. Decrypt querystring - ASPX code-behind Page_Load()
   
   
   if (Request.QueryString["params"] != null)
   {
   string qs = Request.QueryString["params"];
   string deCrypt = QuerystringProtect.DecryptQueryString(qs.Replace(" ", "+"));
   }