@ryanc @sophieschmieg @Lookatableflip I guess it’s not pure software, but anything running on a real computer has a hardware component. The randomness bit is pure software, using whatever it can from the environment as entropy sources, but none of the entropy sources alone (without a hardware random number generator) has enough entropy to be useful, and interrupt timings can sometimes be under attacker control (some fun attacks from the ‘90s involved sending packets at specific timing to influence the entropy collection).