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 > >>> <[email protected]<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: [email protected] MSN: [email protected] Document contents are confidential between original recipients and sender.
