nanog mailing list archives

Re: best way to create entropy?


From: shawn wilson <ag4ve.us () gmail com>
Date: Fri, 12 Oct 2012 00:48:05 +0000

On Fri, Oct 12, 2012 at 12:25 AM, Jonathan Lassoff <jof () thejof com> wrote:
On Thu, Oct 11, 2012 at 5:20 PM, Jimmy Hess <mysidia () gmail com> wrote:
On 10/11/12, shawn wilson <ag4ve.us () gmail com> wrote:
in the past, i've done many different things to create entropy -
encode videos, watch youtube, tcpdump -vvv > /dev/null, compiled a
kernel. but, what is best? just whatever gets your cpu to peak or are

You are referring to  the entropy pool used for  /dev/random  and
crypto operations ?


You could  setup a  video capture card  or radio tuner card,  tune it into
a good noise source,  and arrange for   the bit stream to get  written
 to  /dev/random

Yes, but then you're also introducing a way for an external attacker
to transmit data that can be mixed into your entropy pool.

While certainly a cool hack, I don't think anything like this would be
safe for cryptographic use.


which i guess means my tcpdump is also a bad idea...

i've heard of looking at radio, voltage, and video. i was really
wondering about a good every day solution - something easily
implemented on any computer. so maybe a way of getting random network
traffic or something random from computers around you. i'm not
verisign or any other type of company that needs to generate thousands
of keys in a day, but sometimes i need to generate a half dozen or so,
and my entropy runs out pretty quickly.

the radio idea might work for me if i could get a wire and a cheap
amplifier and plug it into a headphone jack or possibly figure out a
ccd type thing on a motor that would give me noise for my sound card.
but i was hoping for something even more simple than that - maybe wifi
noise?


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