Lavarand

Lavarand, also known as the Wall of Entropy, is a hardware random number generator designed by Silicon Graphics that worked by taking pictures of the patterns made by the floating material in lava lamps, extracting random data from the pictures, and using the result to seed a pseudorandom number generator.

It was covered under the now-expired U.S. patent 5,732,138, titled "Method for seeding a pseudo-random number generator with a cryptographic hash of a digitization of a chaotic system."

Landon Curt Noll, one of the process's originators, went on to help develop LavaRnd, which does not use lava lamps.

[3] Despite the short life of lavarand.sgi.com, it is often cited as an example of an online random number source.

[4][5] As of 2017[update], Cloudflare maintains a similar system of lava lamps for securing Internet traffic, which it also calls the "Wall of Entropy".