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 3D Folding Animation]()
Google Plus provides loads of inspiration for front-end developers, especially when it comes to the CSS and JavaScript wonders they create. Last year I duplicated their incredible PhotoStack effect with both MooTools and pure CSS; this time I'm going to duplicate...
![JavaScript Promise API]()
While synchronous code is easier to follow and debug, async is generally better for performance and flexibility. Why "hold up the show" when you can trigger numerous requests at once and then handle them when each is ready? Promises are becoming a big part of the JavaScript world...
![Full Width Textareas]()
Working with textarea widths can be painful if you want the textarea to span 100% width. Why painful? Because if the textarea's containing element has padding, your "width:100%" textarea will likely stretch outside of the parent container -- a frustrating prospect to say the least. Luckily...
![Six Degrees of Kevin Bacon Using MooTools 1.2]()
As you can probably tell, I try to mix some fun in with my MooTools madness but I also try to make my examples as practical as possible. Well...this may not be one of those times.
I love movies and useless movie trivia so naturally I'm...
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!