http://svn.apache.org/repos/asf/shindig/trunk/features/src/m...
From the file: This code implements a safer random() method that is seeded from screen width/height and (presumably random/unguessable) mouse movement, in an effort to create a better seed for random().
Its aim is to solve the problem of gadgets that are relying on secret RPC tokens to validate identity.
For example, most people on facebook move their pointers to check their notifications/new messages/friend requests. Wouldn't that produce a lot of "not so random" random numbers?
(I am not looking to start a conversation on how random random numbers are, just curious on why they used this specific technique)
Easiest way is probably with a webcam, which will also give you a pretty good bitrate. The general schema is to read out the bias noise. You do this by blocking out any incoming light to get dark noise + bias noise. Dark noise is an assumed static shift due to CCD characteristics, so read N frames of this and look for the median signal. Subtract that off and you've got the bias, or at least something that's close enough for a weekend project.
Better version, start reading up on the math of noise sources in whatever device you want to use for a sensor. Also do an analysis of N samples to see how close the result comes to the expectation value given the type of noise involved and what deviation is expected at N samples.
you could also point the camera at a flat white surface - that would give you a lot more noise (so much you probably don't need to worry about subtracting anything, if you just take the least significant bits from each pixel)
[i hope i'm right - i wrote astronomy image reducing software for a living]
