[Noisebridge-discuss] Group order of Entropy Keys: hardware random number generators

[Brian Cloutier]

> I'm guessing the entropykey is nothing more than a little amp for
> thermal (resistor) noise into an ADC, followed by a whitening
> algorithm. And some kind of device driver to pipe it into /dev/random.

Its quite a bit more than that. According to the website its a transistor
with some reverse voltage applied /just/ to the the point where it breaks
down. Electrons that escape through "quantum tunneling" (I don't know
enough ee to know of this is BS or not, but it sounds like the correct
effect) are then measured. Its actually two transistors, each of which are
measured for entropy, which are combined into a random bit source which is
again measured for entropy. Apparently the stream is then encrypted, the
USB key emulates a serial port, and a small program on the host decrypts
the data and finally feeds it into the entropy pool. (I'm at a loss as to
why its encrypted, but I assume its to prevent some obscure side channel
attack like reading the USB line voltage off an LED on the case flickering
and inferring the data sent)

> Of course we could make a radioactive one with Mike Kan's transistor
> alpha detector trick (pop the top off an old TO-3 can transistor),

I would absolutely /love/ to do this, especially if we hook it into a
banana (potassium is radioactive!) as our source of radiation. We could
then make jokes along the lines of "well how are /you/ going to feed a
million simulated monkeys bashing randomly? A mere /pseudo/random source?"

- Brian
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