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

On Út, 2016-06-21 at 09:05 -0400, Austin S. Hemmelgarn wrote:

On 2016-06-20 14:32, Stephan Mueller wrote:

quoted

[1] http://www.chronox.de/jent/doc/CPU-Jitter-NPTRNG.pdf

Specific things I notice about this:
1. QEMU systems are reporting higher values than almost anything
else 
with the same ISA.  This makes sense, but you don't appear to have 
accounted for the fact that you can't trust almost any of the entropy
in 
a VM unless you have absolute trust in the host system, because the
host 
system can do whatever the hell it wants to you, including
manipulating 
timings directly (with a little patience and some time spent working
on 
it, you could probably get those number to show whatever you want
just 
by manipulating scheduling parameters on the host OS for the VM
software).

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.

-- 
Tomas Mraz
No matter how far down the wrong road you've gone, turn back.
                                              Turkish proverb
(You'll never know whether the road is wrong though.)