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Re: where is my randomness?

From: Matthew Dillon <dillon@xxxxxxxxxxxxxxxxxxxx>
Date: Tue, 24 Jan 2006 10:17:25 -0800 (PST)

::> pair without randomness?
::Does this mean all DragonFly hosts have the same private/public key?
:    It looks like we do have an issue.  Keyboard randomness is still being
:    added, but it looks like the interrupt randomness is not... it has to
:    be turned on with the rndcontrol utility.  That means the only 
:    entropy is going to be the pool hash that occurs when random data is
:    read, which is extremely weak.
:    I am getting different patterns from /dev/urandom on boot, but the
:    results are definitely going to be extremely weak.
:    I will work on fixing this today.

   Addendum... it isn't quite as bad as I thought.  Every time a random
   block is read timer randomness is added back to the pool, but the
   amount of entropy is still going to result in fairly weak results.

   So the answer is no, people's keys will not be the same.  But they
   will not be as strong as they should be, either.

   I have an idea on how to address the issue.  The reason why interrupt
   randomness was not turned on by default was due to the loss in 
   performance due to lack of rate limiting on the calculations.  What I
   will do is add a kernel thread whos sole job is to maintain the entropy
   pool.  The thread will hash various live system parameters plus the 
   timestamp.  Any interrupt will be allowed to trigger the thread but the
   triggering will be rate-limited to something reasonable, like 10 per

   rndcontrol will be removed entirely.

   That should deal with the issue once and for all.

					Matthew Dillon 

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