> I could run it out to md5 and trim the first n chars but that’s not going to be very unique.
What? MD5 going to be orders of magnitude better than what he's given.
> Storing a truncated checksum in a unique field means that the frequency of collisions will increase geometrically as the number of unique keys for a base 62 encoded integer approaches 62^n.
Well, duh. That's a given. And his solution won't do any better.
> I’d rather do it right than code myself a timebomb.
Doing it right would be using a real hash. Not something you came up with over a cup of coffee.
> Pretty random-looking, huh?
If that's his idea of testing for randomness... Use any randomness test and I guarantee you MD5 will preform better and faster.
> This is a minimum security technique.
This is the best piece of advice in the whole piece. Please never ever use this for something you want to be secure. I haven't tried to break it (maybe I'll do that over the weekend), but giving it a first glance I would be willing to bet anyone with some skill would be able to do so.
"Anyone, no matter how unskilled, can design an algorithm that he himself cannot break." -- Bruce Schneier