PHP short unique ID generation using auto_increment?

Question

I would like to generate a short, unique ID without having to check for collisions.

I currently do something like this, but the ID I currently generate is random and che

Answer 1

I think this will never be really secure, as you only need to find the encryption method behind the short unique string to hijack an ID. Is checking for collisions in a loop really that problematic in your setting?