Re:Convert standard Geiger counter to RNG
by lxgr on Monday November 13, 2023 @04:26PM
(#38255628)
One important thing this does not achieve is forward and backward secrecy.
A proper PRNG periodically irreversibly mutates its internal state (which gives you the property of not being able to retrieve past outputs in case of a point-in-time system compromise) and also incorporates additional entropy into its internal state whenever it becomes available (which makes it impossible to predict all future outputs after a point-in-time compromise).
Backward secrecy can be achieved by completely replacing your current state with some hash function of it, i.e. completely deterministically; forward secrecy needs additional entropy, so it's not always feasible.
A proper PRNG periodically irreversibly mutates its internal state (which gives you the property of not being able to retrieve past outputs in case of a point-in-time system compromise) and also incorporates additional entropy into its internal state whenever it becomes available (which makes it impossible to predict all future outputs after a point-in-time compromise).
Backward secrecy can be achieved by completely replacing your current state with some hash function of it, i.e. completely deterministically; forward secrecy needs additional entropy, so it's not always feasible.