“The article appearing below was one of my recent posts to the sci.crypt newsgroup. These are some notes about building a hardware random bit generator. Johnny von Neumann once said that anybody who contemplates arithmetic methods for the generation of random numbers is in a state of sin. What he meant by that is this: if you try to generate random numbers using only software, the results will necessarily depend on the state of your machine at the outset of the process, and are therefore (at least in principle) insecure. That is, somebody could conceivably reconstruct your allegedly random bitstream.”