using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.IO;
using System.Security.Cryptography;
using System.Web;
namespace Common
{
public class QueryStringModule : IHttpModule
{
// 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 = "bnsingh";
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("~/Common/ErrorHandler.aspx?ErrorMsg=" + ex.Message);
//context.Response.Redirect("~/error.aspx?error="+ex.Message);
}
}
/// <summary>
/// Parses the current URL and extracts the virtual path without query string.
/// </summary>
/// <returns>The virtual path of the current URL.</returns>
private static string GetVirtualPath()
{
string path = HttpContext.Current.Request.RawUrl;
path = path.Substring(0, path.IndexOf("?"));
path = path.Substring(path.LastIndexOf("/") + 1);
return path;
}
/// <summary>
/// Parses a URL and returns the query string.
/// </summary>
/// <param name="url">The URL to parse.</param>
/// <returns>The query string without the question mark.</returns>
private static string ExtractQuery(string url)
{
int index = url.IndexOf("?") + 1;
return url.Substring(index);
}
#region Encryption/decryption
/// <summary>
/// The salt value used to strengthen the encryption.
/// </summary>
private readonly static byte[] SALT = Encoding.ASCII.GetBytes(ENCRYPTION_KEY.Length.ToString());
/// <summary>
/// Encrypts any string using the Rijndael algorithm.
/// </summary>
/// <param name="inputText">The string to encrypt.</param>
/// <returns>A Base64 encrypted string.</returns>
public 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());
}
}
}
}
/// <summary>
/// Decrypts a previously encrypted string.
/// </summary>
/// <param name="inputText">The encrypted string to decrypt.</param>
/// <returns>A decrypted string.</returns>
public 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);
}
}
}
}
public static string EncryptPassword(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 Convert.ToBase64String(memoryStream.ToArray());
}
}
}
}
#endregion
}
}