That title is really misleading; this hack doesn’t require a lava lamp… anymore. I initially went googling for a 1996 project at SGI that generated random numbers by taking photos of a lava lamp. The lava lamp was chosen because of its chaotic nature. I was suprised to find that SGI had patented/trademarked the lavarandtm technology. The system required you to use IRIX, took up a lot of space, and because of patents wasn’t easy to implement. In 2000 the engineers behind the original decided to develop an open source alternative know as LavaRnd (note the capital “L” and “R” ;-). This iteration doesn’t use a lava lamp. Its source of chaos is camera with the lens cap on. The gain on the CMOS sensor is cranked all the way up to create a really noisy image. The image data is then sent through an algorithm to generate the random numbers. If you want to see the original project you’re going to have to ask the Wayback Machine.