Vbulletin 3rd Party Login Authentication In .net?

I have a vbulletin forum and want my program users to be able to use their same usernames and passwords they do to login my vbulletin forum. My program is done except for the user authentication. I have searched and googled for weeks now, here is what I know:

� vbulletin 3.8.4 uses, md5(md5($password) . $salt)

� I know how to get the Salt and stored hash from the mysql "user" table.

� I know how to connect to my database without any issues.

I used this code I found here and just modified 3 lines so I could try to get it to work. The code works fine for md5 + salt but as you know I need it to do this: md5(md5($password) . $salt)

Imports System
Imports System.Security.Cryptography
Imports System.Text
Public Class Form1

[code]....

After I can do this I will be able to code my program to retrieve the users salt and compare the hash to the one stored in my mysql database.