Common ways to generate entropy in a way that’s friendly to computers include: measuring noise from a zener (or other electronic component), delta between two o

Common ways to generate entropy in a way that’s friendly to computers include: measuring noise from a zener (or other electronic component), delta between two or more oscillators, or timing between external events (eg keystrokes, packets, etc). These are all super cheap to manufacture (~$1). If you want to go high end, you can spent ~$1000 and get a generator based on some quantum property (photon spin or background radiation detector). Computers will typically combine two or more sources of entropy. In newer tls version handshakes, the entropy from both, the server and client comes into play. So there’s ways to build defense in depth.