[Karl] was in need of a hardware random number generator, but is needs had a few caveats: it needed to be cheap, and sufficiently random. Random number generation can get quite crazy with Geiger tubes ...

There are a great variety of ways to build a random number generator, and similarly many ways to generate numbers that appear random, but in a pure mathematical sense generally aren’t. [Daniel Valuch] ...

Random number sequences are essential to a host of encryption schemes. But true randomness in the strict sense is not possible in the classical world; it only occurs in quantum-mechanical processes.