On Thu, May 15, 2008 at 06:04:04PM -0400, Jeff Garzik wrote:

quoted

I have seen embedded systems with zero entropy, and dubious entropy might 
there be better than no entropy at all.
Or am I wrong on the latter?

It's also relevant to the discussion to note that input data to kernel 
devrandom is mixed, and we can control the amount of "credit" applied to 
incoming entropy.

Sure, and one possible thing to do is to simply always input the
interrupt information to the random number generator, but give it a
"entropy credit" of 0.  That has the net result of potentially
improving the entropy found in /dev/random and /dev/urandom, but not
necessarily compromising /dev/random, since /dev/random's output is
throttled by the entropy estimate.

The only cost of doing this would be the overhead in sending the
information into the entropy pool.

						- Ted