[RESOLVED] MySQL ID Question

reeksy

I am wondering if there is a field type in MySQL that auto generates a random (but unique) ID value of a set length?

The reason why I'm asking as it will form part of a URL, and I don't want malicious users to be able to guess possible other URLs.

Here's an example:

www.example.com/mysecreturl/?id=5

A malicious user could then look at this and go on to guess others:

www.example.com/mysecreturl/?id=5
www.example.com/mysecreturl/?id=6
www.example.com/mysecreturl/?id=7
...

So, I was wondering if MySQL has a field type that created a (almost hash like) value like so:

www.example.com/mysecreturl/?id=401463f8bf350b5593f715db424bb5d2
www.example.com/mysecreturl/?id=34819d7beeabb9260a5c854bc85b3e44

thus, making it much harder for a malicious user to guess.

Thanks,
Reeksy.

laserlight

You could do this in PHP by using say [man]uniqid/man, possibly with a cryptographic hash. You probably could do the same in MySQL with RAND() and MD5() (or whatever cryptographic hash functions are provided).

reeksy

True, the only issue is that it HAS to be a unique value as it will be the primary key for the table.

Does uniqid() keep a record of previously generated IDs, so that it can guarantee a unique value each time?

Weedpacket

No (if it avoided repeats it wouldn't really be random), but you could use the table itself for that.

An alternative would be to use a source that never (for practical purposes) repeats: [man]microtime/man just returned "1240306699.21642804145813" for me, and it will probably never do that again. You could hash that, too, if you want.

reeksy

Microtome. I like the sound of that. Thanks for the help.