Creating a simple login using XML to store the data

Question

Hello one question I have which I can’t find the solution to is I want to create a login for my application so that single user can login. As I intend only one person to be using the application I wanted to avoid using php and HTTPS. Every example I have seen so far is connecting via some database which I don’t think we need to do as only user will tend to use the app.

I was thinking more along the lines of having a one off registration page for the user when he first downloads the application and when he register stores the username and password in XML. Then allow the user to login where the user will check XML file to see if its correct if so let the user go to the main page, as well as use preference to avoid login if the user wishes to do so.

So my main question is this possible? Saving data using XML when registering and checking against that data in XML when logging in. If so how do I go towards implementing this?