Samba and a crypto library

[Andrew Bartlett]

On Wed, 2015-11-18 at 21:48 +0100, Andreas Schneider wrote:
> On Thursday, November 19, 2015 07:41:52 AM Andrew Bartlett wrote:
> > On Wed, 2015-11-18 at 08:42 -0800, Jeremy Allison wrote:
> > > On Wed, Nov 18, 2015 at 08:03:31AM +0100, Andreas Schneider
> > > wrote:
> > > > On Tuesday 17 November 2015 18:02:33 Andreas Schneider wrote:
> > > > > Hello,
> > > > > 
> > > > > I'm currently working on migrating our MS-BRKP implementation
> > > > > to
> > > > > GnuTLS to
> > > > > get rid of the Heimdal dependency for MIT Kerberos support.
> > > > > I've
> > > > > already
> > > > > migrated everthing which is certificate related to GnuTLS.
> > > > > However there
> > > > > are SHA and HMAC functions which are still used from Heimdal.
> > > > > 
> > > > > To do this I would like to add a depenency to a crypto
> > > > > library.
> > > > > As we are
> > > > > already using GnuTLS for some parts of the could, I would
> > > > > like to
> > > > > use GNU
> > > > > Nettle for the low level crypto stuff. GnuTLS depends on
> > > > > libnettle for the
> > > > > low level crypto.
> > > > > 
> > > > > https://www.lysator.liu.se/~nisse/nettle/nettle.html
> > > > > 
> > > > > https://git.lysator.liu.se/nettle/nettle
> > > > > 
> > > > > The license is LGPLv3, GPLv2 and GPLv3.
> > > > > 
> > > > > The crypto operations are mostly written in assembler and
> > > > > also
> > > > > use cpu
> > > > > optimized versions like aesni.
> > > > > 
> > > > > It is really up to date and implement state of the art crypto
> > > > > like chacha-
> > > > > poly1305, Curve25519 etc. The development seems active and
> > > > > healthy.
> > > > > 
> > > > > If we agree I would also suggset not only to use it for MS-
> > > > > BRKP
> > > > > but also
> > > > > replace lib/crypto in future.
> > > > 
> > > > Ok, then I will go ahead. I guess people will start to discuss
> > > > and
> > > > complain as
> > > > soon as I remove lib/crypto ;)
> > > 
> > > I took a look at it and it seemed fine :-). Just didn't
> > > get chance to reply. Does it integrate with crypto-offload
> > > engines ?
> > 
> > Both it and libnettle seem to do it for some ciphers.  See
> > lib/crypto/REQUIREMENTS for some notes we collected earlier this
> > year,
> > and see some of the other threads titled 'crypto' for the other
> > work
> > that was done to use a possible pluggable API.
> > 
> > In particular see:
> > https://git.samba.org/?p=metze/samba/wip.git;a=shortlog;h=refs/head
> > s/ma
> > ster3-smb-crypto
> > 
> > That said, I'm happy with just expanding our dependency on gnutls
> > for
> > now.
> 
> I've changed the backupkey torture test to only use gnutls API. I
> will do the 
> same for the rpc server now.
> 
> I've discussed libnettle with Metze and Volker today and I've also
> talked to 
> Nikos a collegue of mine and the maintainer for GnuTLS. The project
> is healthy 
> and has a lot of improvements for assembler implementation of the
> ciphers so 
> they are faster.
> 
> Also the libnettle API is very good and documented. I prefer it over
> OpenSSL.
> 
> The only cipher missing is aes-cmac but I'm sure the maintainer is
> open to a 
> contribution of that cipher.

Thanks for the assessment.  It feels like a good project to depend on,
it has been around for a good time, maintained it's ABI pretty well,
and hasn't raised any concerns from users when we made it a requirement
for the AD DC in 4.2.

Andrew Bartlett

-- 
Andrew Bartlett
https://samba.org/~abartlet/
Authentication Developer, Samba Team         https://samba.org
Samba Development and Support, Catalyst IT   
https://catalyst.net.nz/services/samba