Whitelisting: You Set The Rules For Security
We all know what blacklisting is when it comes to strings: removing specified "bad" characters. While this helps to secure user input, it isn't as secure as whitelisting. Whitelisting is the process of saying "Let me tell you what you can give me" whereas blacklisting says "If I find this, I'll remove it."
A customer recently asked that I create a whitelisting function that allowed letters, digits, whitespace characters, periods, commas, and dashes. Any other characters were to be replaced with spaces.
The PHP
function make_valid($input)
{
return preg_replace('/[^A-Za-z0-9.,\(\)\s-]/',' ',$input);
}
The above function uses preg_match() and a small regular expression to remove the rubbish characters.
![CSS Animations Between Media Queries]()
CSS animations are right up there with sliced bread. CSS animations are efficient because they can be hardware accelerated, they require no JavaScript overhead, and they are composed of very little CSS code. Quite often we add CSS transforms to elements via CSS during...
![Responsive and Infinitely Scalable JS Animations]()
Back in late 2012 it was not easy to find open source projects using requestAnimationFrame() - this is the hook that allows Javascript code to synchronize with a web browser's native paint loop. Animations using this method can run at 60 fps and deliver fantastic...
![Input Incrementer and Decrementer with MooTools]()
Chris Coyier's CSS-Tricks blog is everything mine isn't. Chris' blog is rock star popular, mine is not. Chris prefers jQuery, I prefer MooTools. Chris does posts with practical solutions, I do posts about stupid video-game like effects. If I...
![CSS Fixed Position Background Image]()
Backgrounds have become an integral part of creating a web 2.0-esque website since gradients have become all the rage. If you think gradient backgrounds are too cliche, maybe a fixed position background would work for you? It does provide a neat inherent effect by...
Your way for whitelisting is quite nice. It’s like in Flash where you can specify exactly what characters are allowed by the user.
This method may work well as a common security filter that replaces get_magic_quotes_gpc(), strip_tags() and htmlentities().
Good work as usual!