Re: How can I build OSSP UUID support on Windows to avoid duplicate UUIDs?

From: "Robert Haas" <robertmhaas@gmail.com>
> ISTM that the biggest problem is that we don't have a random number
> generator which generates enough bits of randomness to implement
> uuid_generate_v3.  I think relatively few people would cry if we
> didn't support uuid_generate_v1(), and the others all look simple
> enough, provided there's somewhere to get lots of random bits.
>
> On Linux, it seems like we could get those bits from /dev/urandom,
> though I'm not sure how efficient that would be for the case where
> many UUIDs are being generated at once.  But that wouldn't be very
> portable.  It's tempting to think that we'd need a PRNG that generates
> wider values, for which we might find other application also.  But I'm
> not volunteering to be the one to create such a thing.

OpenSSL provides rand_bytes() which generates random bytes of any length. 
It uses /dev/urandom or /dev/random on UNIX/Linux and Crypto API of 
Microsoft on Windows.

Regards
MauMau