Re: is "premature next" a real world rng concern, or just an academic exercise?

From: Dominik Brodowski
Date: Fri May 13 2022 - 02:26:34 EST


Am Thu, May 12, 2022 at 01:47:06PM +0200 schrieb Jason A. Donenfeld:
> But on the other hand, it appears that none of us really thinks that
> premature next is a real problem worth complicating designs over. So
> maybe we can just say that it is nice when the silicon in one way or
> another helps with premature next, but maybe not an explicit must have.
> So where does that leave us?
>
> - Systems with RDSEED/RDRAND don't have premature next, due to the above
> KDF salt. This is probably the majority of systems out there these
> days. This also applies to the sleep resumption notification (and the
> vmgenid one), and I suspect that most systems with S3 or S0ix or
> whatever else these days also probably have RDRAND.

... and most of these systems have TPM chips with a RNG, which is (alas)
usually only used at system startup, as that hw_rng device sets its quality
to 0 (meaning untrusted). So there's also room for improvement involving
these hw rng devices.

Thanks,
Dominik