Comment by cyanmagenta

It’s an interesting question whether that could be fixed. I think the answer is Yes. If the author didn’t do any scrambling, and just displayed UUIDs in numeric order, then it’s trivial to enumerate search results in order. Likewise, if you do something like adding a constant mod 16 to each hex digit, you could do the same thing when you generate UUIDs matching a substring. So the question becomes whether you could find something like that that gives a sufficiently convincing illusion of entropy but is still reversibile when you hold a subset of the digits constant. And it seems like it should be.