I’m implementing a simple game in Javascript, and am interested in having an online highscores table for it, so that players can compete against one another. I’ve two concerns about this:
- What is the simplest server-side program I need for this purpose? I don’t need a full-fledged “web application”, just something simple that gets POST requests with highscores, updates a database and sends back lists of scores. I’m familiar with Django. What are your suggestions?
- How can I make the highscores table reasonably secure? I’m aware that making it bulletproof against competent and dedicated hackers is difficult, but I wouldn’t want anyone with access to the Javascript sourcecode to be able to submit fictitious scores too simply. Any tools for this purpose?
1.) Any CGI script that can talk to a database and understand JSON, or other format of your choice, will do the work.
However, if you’re familiar with Django, building your server on top of Django would be the most simple, in the sense of what you have to learn and how much application code you have to write. Seemingly simple CGI script can turn out rather complex if you write it from scratch.
I found django-piston to be a handy Django app to quickly write a REST-style API server. It supports JSON so it should be easy to interface with your JavaScript game.
2.) The most casual cracker will go for a replay attack and its variants: peek at the page source and execute a JavaScript function, intercept HTTP requests and resend it (should be easy with a Firefox add-on like Tamper Data).
To counteract the former, you can obfuscate the source code and HTTP body;
The latter can be prevented by requiring all update requests to include an one-time password (“session token” in the Wikipedia article) that was recently acquired from the server.