Question

I need to encrypt and decrypt a querystring in ASP.NET.

The querystring might look something like this:

http://www.mysite.com/report.aspx?id=12345&year=2008

How do I go about encrypting the entire querystring so that it looks something like the following?

http://www.mysite.com/report.aspx?crypt=asldjfaf32as98df8a

And then, of course, how to I decrypt it? What’s the best encryption to use for something like this? TripleDES?

Answer 1

Here is a way to do it in VB From: http://www.devcity.net/Articles/47/1/encrypt_querystring.aspx

Wrapper for the encryption code: Pass your querystring parameters into this, and change the key!!!

Private _key as string = '!#$a54?3' Public Function encryptQueryString(ByVal strQueryString As String) As String     Dim oES As New ExtractAndSerialize.Encryption64()     Return oES.Encrypt(strQueryString, _key) End Function  Public Function decryptQueryString(ByVal strQueryString As String) As String     Dim oES As New ExtractAndSerialize.Encryption64()     Return oES.Decrypt(strQueryString, _key) End Function 

Encryption Code:

Imports System Imports System.IO Imports System.Xml Imports System.Text Imports System.Security.Cryptography  Public Class Encryption64     Private key() As Byte = {}     Private IV() As Byte = {&H12, &H34, &H56, &H78, &H90, &HAB, &HCD, &HEF}      Public Function Decrypt(ByVal stringToDecrypt As String, _         ByVal sEncryptionKey As String) As String         Dim inputByteArray(stringToDecrypt.Length) As Byte          Try             key = System.Text.Encoding.UTF8.GetBytes(Left(sEncryptionKey, 8))             Dim des As New DESCryptoServiceProvider()             inputByteArray = Convert.FromBase64String(stringToDecrypt)             Dim ms As New MemoryStream()             Dim cs As New CryptoStream(ms, des.CreateDecryptor(key, IV), _                 CryptoStreamMode.Write)             cs.Write(inputByteArray, 0, inputByteArray.Length)             cs.FlushFinalBlock()             Dim encoding As System.Text.Encoding = System.Text.Encoding.UTF8             Return encoding.GetString(ms.ToArray())         Catch e As Exception             Return e.Message         End Try     End Function      Public Function Encrypt(ByVal stringToEncrypt As String, _         ByVal SEncryptionKey As String) As String         Try             key = System.Text.Encoding.UTF8.GetBytes(Left(SEncryptionKey, 8))             Dim des As New DESCryptoServiceProvider()             Dim inputByteArray() As Byte = Encoding.UTF8.GetBytes( _                 stringToEncrypt)             Dim ms As New MemoryStream()             Dim cs As New CryptoStream(ms, des.CreateEncryptor(key, IV), _                 CryptoStreamMode.Write)             cs.Write(inputByteArray, 0, inputByteArray.Length)             cs.FlushFinalBlock()             Return Convert.ToBase64String(ms.ToArray())         Catch e As Exception             Return e.Message         End Try     End Function  End Class