tptacek is right. It's a cool art installation, but for practical purposes this is utterly useless. A modern hardware RNG (which is entirely silicon based) generates random bits at a vastly higher rate, and with better reliability, like built-in continuous statistical tests, than something rigged together with lava lamps, Geiger counters or the like.

I've built those kinds of science projects, and they are great for fun and for learning, but they are not practical or necessary in any production environment.

> but they are not practical or necessary in any production environment

But do they provide any greater advantage or greater utility to your "science projects" other than being cheaper to run? What do higher rates and higher reliability have to do with being able to create a non-deterministic and thus truly random bit? In other words, how on earth would a hacker even conceivably be able to hack the lava lamp setup?

The writing by Cloudflare on the subject (hyperlinked here several times already, so I won't) indicates that the utility that Cloudflare sees in it is in militating against the sort of malicious entropy source attacks described by Bernstein. The idea is that one has a set of disparately placed entropy sources, in Cloudflare's head office (of which the lava lamps are just one) and in Cloudflare's data centre, making it hard to supplant one and simultaneously observe all of the others.

I am not sure that Cloudflare is correct about this, however. It seems to me that at the point where the entropy sources are finally mixed, on the beacon machine in the datacentre, it does not matter that the lava lamps are far away, and this factor is just window dressing. The data that they generate has to arrive at the beacon machine on a serial port, Ethernet interface, or other input device, and that is the point where it can be observed/supplanted.

I think you're confusing the medium with which this achieved versus it's utility.

Surely you're not suggesting PRNG/DRBG isn't completely safe from hacking?

Real world RNGs get randomness from two sources: (1) the timings of random events on the machine (primarily network traffic), or (2) a hardware device that runs several oscillators on different clocks and detects coincidence in the derived square waves. Even #1 alone is normally sufficient in the real world. While you're right that there are attacks against RNGs, it's never going to be because an attacker gets control of every little bit of stray RF in your data center such that he can control the exact timing of packet arrival, packet retransmits, etc.

I don't even understand this question. Can you reword it?

Sure. I'm struggling to understand what utility your questioning. Is is it the fact that they are using a hardware based random generator or the way in which they are using a hardware generator (e.g. lava lamps)?

If the former - my question would be - surely you, as a security expert, would agree that a hardware random generator is more secure than a software based one (PseudoRandomNumberGenerator or DeterministicRandomBitGenerator)?

If the latter - why does the way in which they use a hardware generator matter as long as it provides some utility and advantage over a software-based one which has a deterministic set of numbers?