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.
![Conquering Impostor Syndrome]()
Two years ago I documented my struggles with Imposter Syndrome and the response was immense. I received messages of support and commiseration from new web developers, veteran engineers, and even persons of all experience levels in other professions. I've even caught myself reading the post...
![Send Text Messages with PHP]()
Kids these days, I tell ya. All they care about is the technology. The video games. The bottled water. Oh, and the texting, always the texting. Back in my day, all we had was...OK, I had all of these things too. But I still don't get...
![Duplicate the jQuery Homepage Tooltips Using Dojo]()
The jQuery homepage has a pretty suave tooltip-like effect as seen below:
Here's how to accomplish this same effect using Dojo.
The XHTML
The above HTML was taken directly from the jQuery homepage -- no changes.
The CSS
The above CSS has been slightly modified to match the CSS rules already...
![MooTools Link Fading]()
We all know that we can set a different link color (among other properties) on the hover event, but why not show a little bit more dynamism by making the original color fade to the next? Using MooTools 1.2, you can achieve that effect.
The MooTools...
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!