How should I create my GUID?

Question

I'm going to be uploading images to a system and need them to be referenced by a non-sequential unique ID. I've read a little about GUIDs, and I'm wondering what the best approach to making one in PHP is. Should I md5() the current timestamp and salt it, or will PHP's uniqueid (http://www.php.net/manual/en/function.uniqid.php) function be sufficient enough?

Thanks!

Answer 1

Since uniquid uses the current time in microseconds to generate the guid, there is virtually no chance you'll ever run into the same one twice.

So if you're just using it to make unique filenames, uniqid() will be sufficient. If you want to prevent users from guessing the guid, you might as well make it harder and md5 it as well.

Answer 2

GUID is Microsoft's version of UUID. PHP's uniqid is version 4 of UUID. Definitely good enough.