[namelost]

UUIDs are not secure unless they are version 4 (random) and generated from a secure randomness source.

[jimktrains2]

What do you mean by secure? Unpredictable?

[wruza]

The same applies for any unique ids in general.

[dchest]

Yes, but the holy UUID standard specifies multiple ways of generating them from sticks and stones, invented before people knew how to properly generate random bytes.