[Cryptography] cheap sources of entropy

[Peter Gutmann]

Bill Frantz <frantz at pwpconsult.com> writes:
>On 1/20/14 at 9:13 AM, crypto.jmk at gmail.com (John Kelsey) wrote:
>> The problem is, nobody makes *everything* they use.  A sufficiently
>> resourceful attacker might attack your device on all kinds of
>> levels, and you can't possibly check them all yourself.  
>
>Hmm, 12AX7s cost about $15 and burn a bunch of power. How many do I need to
>perform useful computation? Using the LGP-30 computer as an example, not very
>many. In any case, there is probably a simple enough technology where
>concerns about back doors devolve into pure paranoia.

If you're going to do that, you may as well go with relays:

http://web.cecs.pdx.edu/~harry/Relay/index.html

Or if you need something a bit faster, try the MT15:

http://6502.org/users/dieter/mt15/mt15.htm

All you need is about 3,000 BC547/557s.  Working at that level, you *can*
actually check everything yourself.

Peter.