entropy

[Roberto Ragusa]

Don Quixote de la Mancha wrote:

> But it's just like a bunch of Physicists to go to all the trouble to
> build a randomness source out of a Geiger counter.  A noisy resistor
> or diode would have done the job just as well.

IMHO, 16 bit sampling of a mic with high gain will produce at least 100 bit/s
of entropy, especially in a noisy environment (server room with a lot
of fans).

A webcam could easily provide 1000 bit/frame, so 25000 bit/s. A 640x480
frame has about 300000 pixels, so we are just asking one bit of randomness
out of 300 sampled pixels. I would guess the quality of the randomness
would be really good; extra points if the webcam is pointed to something
dynamic and unpredictable (traffic out of the window, glass of water,
mirror, unstable webcam support, flickering lights,...).

Obviously you should sample the entire frame and then hash the hell
out of it to get to the desired number of bits.

-- 
   Roberto Ragusa    mail at robertoragusa.it