DIY RNGs [was: Re: Curious RNG stalemate [was: use of cpunks]]

Kelly John Rose iam at kjro.se
Tue Oct 22 08:37:37 PDT 2013


Yeah. You just need a noisy channel. Radiation is really overkill.

You probably could use quantum tunneling on a silicon chip to produce a
reliably random noise source small enough for a an port.

The issue, however becomes the computer itself. It isn't hard to muck up a
serial port so that you wouldn't even know you aren't getting the true
data.

On Tuesday, October 22, 2013, Cathal Garvey wrote:

> If the particle flux is high enough for it to be usefully rich in random
> data, you could just hash the image output and use the hash outputs as
> an entropy source.
>
> However, you'd want to be careful that you:
> A) Use a good hash, and perhaps double-hash to be paranoid
> B) Try to measure and correct/alarm for the flux of your radioisotope as
> it decays, though depending on the isotope perhaps this isn't important.
>
> Thinking all the thoughts on this channel through, I'm beginning to
> wonder if the easiest answer isn't just a vibrating surface covered in
> sand with a camera pointed at it, hashing the output. :)
>
> On 22/10/13 16:15, Ted Smith wrote:
> > On Tue, 2013-10-22 at 00:07 -0700, Andy Isaacson wrote:
> >> On Fri, Oct 18, 2013 at 11:42:21AM -0400, Sandy Harris wrote:
> >>> On Thu, Oct 17, 2013 at 12:56 PM, grarpamp <grarpamp at gmail.com<javascript:;>>
> wrote:
> >>>> Problem is, apparently no one is solving it, so round and round
> >>>> it goes...
> >>>
> >>>> Now if someone would just sell a completely open discrete logic
> >>>> serial port hw entropy source for under $50... that would end
> >>>> a lot of the talk. Even with a more costly radiation source rather
> >>>> than other phenomena you'd still likely make good profit ...
> >>>
> >>> If you have an audio device free or can add one and are using
> >>> Linux, I'd say Turbid is the obvious solution:
> >>> http://www.av8n.com/turbid/paper/turbid.htm
> >>>
> >>> Open source, available for over a decade, well thought out
> >>> and well documented. It even has a proof, using only some
> >>> quite mild assumptions, that it gives almost perfect entropy
> >>> in the output. What's not to like?
> >>
> >> It's super frustrating that Turbid assumes you are going to
> >> reverse-engineer the amplifier stage of your sound card in order to set
> >> some difficult-to-understand parameters which apparently can completely
> >> break it's ability to extract entropy if set incorrectly.  (See the
> >> installation instructions in section 12 of the paper linked above.)
> >>
> >> It would be much better for it to have a default set of parameters (or
> >> an autotuned parameter engine) that have a very high likelihood of
> >> giving acceptable results upon "apt-get install turbid" on some
> >> arbitrary hardware.
> >>
> >> I mean, seriously.  The Turbid authors appear to assume that every
> >> person who installs Turbid is going to build a custom Y-audio cable and
> >> put a voltmeter (set to the correct mode of course!) on the outputs of
> >> their sound card.  WTF?
> >>
> >> It's fine if conservative, default settings result in Turbid getting
> >> only 100 bits of entropy per second rather than 100 Kbit/sec.  Mix it
> >> into /dev/urandom and call it a day.
> >>
> >> -andy
> >
> > A while ago, a friend and I bought a smoke detector and a webcam, hacked
> > them together, and built this:
> > http://www.inventgeek.com/Projects/AlphaRad/OverView.aspx
> >
> > It actually works; when you view the webcam you can see the little
> > points of light where an alpha particle hits the sensor.
> >
> > However, there wasn't really any software to support it as an RNG, so
> > it's just sitting around.
> >
> > Is it possible to make an entropy source out of something like that? If
> > so, it was a really simple (less than two hours IIRC) build, and it cost
> > about $40.
> >
>


-- 
Kelly John Rose
Toronto, ON
Phone: +1 647 638-4104
Twitter: @kjrose
Skype: kjrose.pr
Gtalk: iam at kjro.se
MSN: msn at kjro.se

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