Problem 4b: How do we generate secret keys?

• It sounds so easy: “Just pick a random key”

• No good standard source of computer randomness

  • pseudorandom generators are just deterministic functions that require a random seed
  • OS state (time-of-day, PID) is very low entropy
  • user keyboard input is very unreliable

• Best practical options aren’t very good

  • inter-event timing (keyboard, network), timing loops, fast clocks and interval timers
  • better would be /dev/random, or hardware generator

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