Re: [PATCH v5 0/7] /dev/random - a new approach

Hi!

quoted

On Sun 2016-06-19 17:58:41, Stephan Mueller wrote:

quoted

Hi Herbert, Ted,

The following patch set provides a different approach to /dev/random which
I call Linux Random Number Generator (LRNG) to collect entropy within the
Linux kernel. The main improvements compared to the legacy /dev/random is
to provide sufficient entropy during boot time as well as in virtual
environments and when using SSDs. A secondary design goal is to limit the
impact of the entropy collection on massive parallel systems and also
allow the use accelerated cryptographic primitives. Also, all steps of
the entropic data processing are testable. Finally massive performance
improvements are visible at /dev/urandom and get_random_bytes.

Dunno. It is very similar to existing rng, AFAICT. And at the very
least, constants in existing RNG could be tuned to provide "entropy at
the boot time".

The key differences and thus my main concerns I have with the current design 
are the following items. If we would change them, it is an intrusive change. 
As of now, I have not seen that intrusive changes were accepted. This led me 
to develop a competing algorithm.

Well, intrusive changes are hard to do, but replacing whole subsystems
is even harder -- and rightly so.

- There was a debate around my approach assuming one bit of entropy per 
received IRQ. I am really wondering about that discussion when there is a much 
bigger "forcast" problem with the legacy /dev/random: how can we credit HIDs 
up to 11 bits of entropy when the user (a potential adversary) triggers these 
events? I am sure I would be shot down with such an approach if I would 
deliver that with a new implementation.

Well, if you can demonstrate 11 bits is too much, go ahead... I'm sure
that is rather easy to adjust.

But I believe that 1) user is not normally an adversary and 2) the
best thing for him to do would still be "pressing nothing". It will be
hard to press keys (etc) with great enough precision...

Best regards,
									Pavel

-- 
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