This is a remarkable piece of lateral thinking by the folks at CloudFlare. It’s well known that random numbers are difficult to generate. It can be simulated, but any coded algorithm that generates the numbers can potentially be reversed engineered.
So CloudFlare borrowed an idea from Silicon Graphics to use a wall of lava lamps to generate a very random image. That image, including the random static and artifacts is used to seed an algorithm which generates a random number. Additionally, image information from two other sources in the world are also combined with the lava lamp image to create an algorithm seed that is geographically dispersed as well.
Kurt Kohlstedt reports in his article on Web Urbanist,
The lamps are recorded on video in Cloudflare’s San Francisco headquarters, then translate those movements to create encryption keys for the web.
It’s a remarkable and very cool solution to a very difficult problem. 10% of the web services on the Internet flow through CloudFlare and they are, in part, protected by lava lamps.