On 07/25/2012 08:10 AM, Theodore Ts'o wrote:
Aside from whether it's better to do this step in
xfer_secondary_pool() or extract_entropy() ...
By the way, I looked at doing this in xfer_secondary_pool()... the
problem there is that xfer_secondary_pool() is called exactly once per
invocation of extract_entropy() and so there is no way to make it inject
the same amount of material as it consumes.
One could put it in extract_entropy[_user]() and if you prefer I'll
rewrite the patch to do that, however that code would look very similar
to the one in extract_buf() -- pretty much the same code in the caller
rather than the callee -- but would have the same downside with being
processed on 10-byte chunks because the final buffer might be misaligned
and/or partial. It would mean just running it once rather than twice
per output datum, but I actually expected you would prefer the
additional mashing and security margin.
-hpa
P.S. Anyone who have any insider info on when we can expect the SHA-3
selection? Switching to SHA-2 at this time with SHA-3 around the corner
(and based on numbers I have seen, likely to be faster) seems a bit silly...
--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.
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