It cannot be averaged out, as there is no way to take multiple samples. Look at it: for any specific input it always sleeps for a deterministic amount of time.

It cannot be averaged out, as there is no way to take multiple samples. Look at it: for any specific input it always sleeps for a deterministic amount of time. Unlike random timing noise, which can be averaged away. You take averages and all you know is the value of (actual time + some unknown value) very precisely. That doesn't help you. (He is, however, missing that it should also have a random salt, generated once and stored.) Of course, this is still breakable most of the time.