[Gllug] Questions arising from the random discussions...

[Nix]

On 3 Aug 2010, Walter Stanish stated:

>>> It may be of interest to read Documentation/hw_random.txt in /usr/src/linux
>>
>> That's about Linux's support for *hardware* random number generators (that
>> is to say, those that need direct kernel support).
>
> Yes, they're in most modern PCs

No they aren't. Some VIAs have them. Intel put them in some machines
briefly and then stopped. I think that's it. Most machines these days
have no sources of entropy but disk timings and keyboard and mouse I/O.
Headless machines have even less. Headless machines with SSDs have none
at all. (Network cards used to be considered acceptable sources of
entropy, but because the timing of network packets is controllable by an
attacker they were removed years from the list of devices contributing
to entropy years ago.)

>                                  and the original question was "where does
> the stream for /dev/random and /dev/urandom come from ..."

'Entropy'. Where the entropy comes from is a source of endless
contentious argument over what halfbaked kludge of environmental noise
monitoring happens to be good enough for the kernel pool. :)
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