ASP.NET to WordPress SSO with HttpWebRequest

I am attempting to create a single sign on experience between an asp.net site and a wordpress site using a simple form POST method. I have built a simple php page that uses the native wordpress functions wp_insert_user and wp_signon to create user account in the mysql db and sign them in. In my asp.net ‘create new user’ page code behind, I’m using the post method of an HttpWebRequest to send the required information to the php page.