[Samba] Strong cryptography for Kerberos available?

[Andrew Bartlett]

On Sat, 2014-07-05 at 18:11 +0200, Lars Hanke wrote:
> Am 04.07.2014 13:09, schrieb Andrew Bartlett:
> > On Thu, 2014-07-03 at 22:54 +0200, Lars Hanke wrote:
> >> If I query the AD DC I see:
> >>
> >> root at samba4:/# ldapsearch -H  ldap://samba.ad.microsult.de -Y GSSAPI
> >> '(sAMAccountName=mgr)'
> >> SASL/GSSAPI authentication started
> >> SASL username: Administrator at AD.MICROSULT.DE
> >> SASL SSF: 56
> >> SASL data security layer installed.
> >>
> >> I would like to see SASL SSF: 112. Does anyone know whether and where
> >> this can be configured?
> >
> > I don't think it's actually that weak, but the SASL libs probably don't
> > know how to tell any better.  At the very least it would be using
> > arcfour-hmac-md5, perhaps AES if provisioned at a high enough functional
> > level.
> 
> Well, single DES can be brute-forced in less than a day using hardware 
> available at several universities. And there are people driving cars 
> worth more than such a hardware. This is weak!

And is disabled by default in all modern kerberos libs.  See
'allow_weak_crypto' in krb5.conf. 

> Do I interpret your answer correctly that the choice of algorithms is 
> driven by SASL?

No, SASL has no part in selecting the kerberos crypto algorithm.  The
strongest mutually supported algorithm is securely selected between the
KDC, client and server.  

Andrew Bartlett

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