Re: Entropy Pool Contents

From: Phillip Susi
Date: Mon Nov 27 2006 - 11:16:12 EST


Gunter Ohrner wrote:
IMHO something really fishy's going on there. If I explicitely write data
into the pool, it shouldd not stay at "zero", from wwhat I understood about
how /dev/*random work.


<snip>

I'm mainly wondering why writing stuff to /dev/*random does not change the
entropy from zero to at least any low non-zero value...


I ran into this the other day myself and when I investigated the kernel code, I found that writes to /dev/random do accept the data into the entropy pool, but do NOT update the entropy estimate. In order to do that, you have to use a root only ioctl to add the data and update the estimate. I am not sure why this is, or if there is a tool already written somewhere to use this ioctl, maybe someone else can comment?


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