[PATCH] Crypto use in Samba (was: Re: SMB3 encryption performance)

Volker Lendecke Volker.Lendecke at SerNet.DE
Tue Feb 17 03:24:48 MST 2015

On Tue, Feb 17, 2015 at 10:40:26PM +1300, Andrew Bartlett wrote:
> On Tue, 2015-02-17 at 09:14 +0100, Volker Lendecke wrote:
> > On Tue, Feb 17, 2015 at 11:56:01AM +1300, Andrew Bartlett wrote:
> > > The latest unreleased version of GnuTLS seems to provide it.  Also, the
> > > latest protocol version seems to use the GCM mode. 
> > 
> > It will take a couple of years before this trickles into the relevant
> > distros. I think we need to drop GnuTLS then and look for something
> > else. OpenSSL seems impossible because I don't think we can change our
> > license. Another one that advertises HW support is libgcrypt then. Or
> > for this special use case we might grow something on our own? This can't
> > be rocket science.
> I've not done the complete survey of what gcrypt supports, but while it
> appears to support the AES modes we need, they are not hardware
> accelerated (only CBC and CFM modes are).  Naturally we could ask that
> they be added.  I've double-checked, and they do appear to be both
> supported and hardware accelerated in gnutls GIT.  Of course the
> problems you mention above make that difficult also.
> I realise it isn't exactly what you were aiming for (your goal primarily
> being just faster AES), but my view is that we should be getting out of
> the crypto lib business as much as possible, and so trying to find a
> library that has a sane interface, improves our performance and supports
> as much as possible of what we need.
> Towards that goal, perhaps someone can look over gcrypt and any other
> licence-compatible options and see if it at least covers the other
> algorithms we need, and mark it in the file?

Linux AF_ALG looks promising to me. Very likely a bit slower
than calling the instructions in user space, but probably
faster than our current software implementation. If
something else comes along, we can think of our own
abstraction layer.


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