RE: Concurrent access to /dev/urandom

David Schwartz
2004-11-30T02:38:26Z

> On Mon, 29 Nov 2004, Bernard Normier wrote:
>
> >>> I use /dev/urandom to generate UUIDs by reading 16 random bytes from
> >>> /dev/urandom (very much like e2fsprogs' libuuid).
> >>
> >> Why not use /dev/random for such data instead?
> >
> > A UUID generator that blocks from time to time waiting for
> entropy would not
> > be usable.
>
> Especially when used on a box without any effective entropy source - like
> praktically most cheap servers stashed away into some rack.

Assuming most of your cheap servers are running some version of the Intel
Pentium or comparable, they have wonderful entropy sources. Nobody can
predict the oscillator offset between the crystals in the network cards on
both ends and the TSC. This entropy source is mined by the kernel.

DS