Tim May sez: Here's a posting I just sent to sci.crypt, dealing with using alpha particle sources as noise sources for generating one-time pads.

Tim, Why not use a back-biased germanium diode, or other noisy semiconductor junction? Seriously, the NRC has allowed the smoke detector people to spread those little radioactive chunks of Americium for too long.

John Walker of AutoDesk actually built an IBM-PC card that generated random numbers from a radioactive source.

Q: how hard/cheap will it to build a shielded rs232 plud with a noisy diode in it to provide a random number source? I have written on a possible random number source for Sun SparcStations (I and II). I have a program programs the audio chip to take input from mic port 2 (which is not used in a SparcStation) then I turn up the gain in the pre-amps and read the data of the from the DtoA. I do not know how random it is yet (if anyone wants to run some tests for me I will be happy to email them the program) -Pete