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From: Robin Carey <firstname.lastname@example.org>
Subject: Random number generator
I had an idea about how to improve the random number generator in DragonFlyBSD which I would like to share.
There is a bootstrapping problem where it is difficult to get enough "entropy" at boot to ensure the random number generator is fully seeded and completely unpredictable immediately after the system has booted.
Currently the random number generator seeds itself from nanotime() and nanouptime() which introduces a small degree of entropy, but probably not enough to ensure the above requirement is met.
So a possible improvement could be made by introducing more "entropy" at initialisation from a high resolution timer like the TSC - rdtsc() (which is also used in the random number generator - NANOUP_EVENT() - courtesy of Matthew Dillon). That is my suggestion: Use rdtsc() aswell as nanotime() and nanouptime() to ensure the random number generator has enough "entropy" at boot to ensure it is fully seeded and completely unpredictable. If this were done (and true) then you would not need the current ability of the random number generator being able to be seeded from a file - an ability which Matthew Dillon implemented to solve the boot-seeding problem.
I am wondering if there are any other high resolution timers available .....