Re: [PATCH v4 0/5] /dev/random - a new approach

Stephan Mueller
2016-06-21T18:05:08Z

Am Dienstag, 21. Juni 2016, 13:54:13 schrieb Austin S. Hemmelgarn:

Hi Austin,

> On 2016-06-21 13:23, Stephan Mueller wrote:
> > Am Dienstag, 21. Juni 2016, 13:18:33 schrieb Austin S. Hemmelgarn:
> >
> > Hi Austin,
> >
> >>> You have to trust the host for anything, not just for the entropy in
> >>> timings. This is completely invalid argument unless you can present a
> >>> method that one guest can manipulate timings in other guest in such a
> >>> way that _removes_ the inherent entropy from the host.
> >>
> >> When dealing with almost any type 2 hypervisor, it is fully possible for
> >> a user other than the one running the hypervisor to manipulate
> >> scheduling such that entropy is reduced. This does not imply that the
> >
> > Please re-read the document: Jitter RNG does not rest on scheduling.
>
> If you are running inside a VM, your interrupt timings depend on the

The RNG does not rest on interrupts either.

> hpyervisor's scheduling, period. You may not directly rely on
> scheduling from the OS you are running on, but if you are doing anything
> timing related in a VM, you are at the mercy of the scheduling used by
> the hypervisor and whatever host OS that may be running on.
>
> In the attack I"m describing, the malicious user is not manipulating the
> guest OS's scheduling, they are manipulating the host system's scheduling.

Ciao
Stephan