Re: [PATCH] drivers/net: remove network drivers' last few uses of IRQF_SAMPLE_RANDOM

From: Will Newton
Date: Fri May 16 2008 - 09:59:24 EST


On Fri, May 16, 2008 at 2:40 PM, Jeff Garzik <jeff@xxxxxxxxxx> wrote:
> Lennart Sorensen wrote:
>>
>> On Thu, May 15, 2008 at 03:21:49PM -0400, Jeff Garzik wrote:
>>>
>>> "no other form of entropy"? See examples in this thread.
>>
>> So where does one get entropy if not the ethernet adapter on many
>> embedded systems? If you have no mouse, no keyboard, no hardware number
>> generator, just ethernet ports and a serial console that usually
>> receives no input. While ethernet might not be preferable if you have
>> something else, sometimes you really don't have anything else.
>
> Already answered in this thread... EGD illustrates how many sources of
> entropy remain, even in the example you just gave.
>
> Further, you do not want to rely on entropy from a source that declines just
> as network traffic increases.

I don't know egd that well, but from a cursory look it gets data from
such things as w or last (wtmp) which is static on most embedded
boxes. It also uses netstat and snmp - surely this is at least as easy
to manipulate as interrupt timings? I'm not a cryptographer by any
means but it looks as if it works by magic. Last changed 2002, written
in perl. No, I don't think I'll be shipping this on any systems any
time soon.
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