[Security] Enhancements to H.233 and H.234

Even, Roni roni.even at POLYCOM.CO.IL
Tue Sep 17 02:10:39 EDT 2002


Patrick,
I still do not understand number 1 since this tag is in the context of h.233
and should be specified like that.
As for the prime number look at the RFC 2412. H.235 refer to it since it
includes verified prime numbers for 1024 and 1536 and I suggest we have the
same recommendation as H.235. Maybe you should consult with Martin Euchner
Regards
Roni

> -----Original Message-----
> From: Patrick Luthi [mailto:patrick.luthi at tandberg.no]
> Sent: Tuesday, September 17, 2002 12:59 AM
> To: Even, Roni; ITU-SG16 at echo.jf.INTEL.COM
> Subject: RE: [Security] Enhancements to H.233 and H.234
>
>
> Roni,
>
> See my answers in-line!
>
> Regards,
>
> Patrick
>
> At 16:03 9/12/2002 +0300, Even, Roni wrote:
> >Patrick,
> >I looked at the contributions and have some comments.
> >
> >1. In H.233 why the new tag class, why don't you use 11 as
> the rest of H.233
> >messages.
>
> We used 00 because it defines the universal tag class (11
> being context
> specific), and we thought that SE_NULL, as data type null
> message, would
> best belong to that class. This makes it consistent with ASN.1.
>
> >2. By adding the new encryption algorithm you need a longer
> DH prime. In
> >H.235 they have a table in annex D which is based on
> RFC2412. Do you think
> >we should have the option to recommend the same numbers as
> H.235 does.
>
> H.233 nor H.234 are specifying any Diffie Hellman prime values and my
> understanding is that it is left to the implementor to choose
> the best
> value. I see your point, and in the interest of interoperability, a
> specified value would help.
> I will think about how to best integrate some text specifying
> prime values
> in H.234. One idea was to add a note in the section about
> Diffie Hellman
> (clause 4/H.234) saying something (inspired by D.7.1/H.235) like this:
> It is recommended to use a prime value of 512 bits for the
> DES algorithm
> (when exportable security is of concern), 1024 bits for
> Triple DES and AES
> algorithms (when high security is of concern), and 1536 bits
> for Triple DES
> and AES algorithms (when very high security is of concern).
> Would that address your concerns? Any feedback or comments
> are welcomed!
>
>
> >Regards
> >Roni Even
> >
> > > -----Original Message-----
> > > From: Patrick Luthi [mailto:patrick.luthi at TANDBERG.NO]
> > > Sent: Friday, August 30, 2002 1:54 AM
> > > To: ITU-SG16 at echo.jf.INTEL.COM
> > > Subject: [Security] Enhancements to H.233 and H.234
> > >
> > >
> > > Dear experts,
> > >
> > > We would like to share with you 2 proposals for enhancements
> > > to H.233 and
> > > H.234 that we are planning to submit to the October
> meeting of SG16.
> > >
> > > Enhancements to H.233: this contribution proposes to add the
> > > Triple Data
> > > Encryption Algorithm (TDEA or triple DES) and the
> Advanced Encryption
> > > Standard (AES) to the list of algorithms in H.233 along with
> > > corrections of
> > > some inconsistencies.
> > >
> > > Enhancements to H.234: this contribution proposes changes to
> > > H.234 to allow
> > > the exchange of asymmetric length of encryption keys.
> > >
> > > Please let me know if you have any suggestions or comments!
> > > The plan would
> > > be to ask for Consent for both recommendations at the
> closing of the
> > > upcoming SG16.
> > >
> > > Best regards,
> > >
> > > Patrick
> > >
> > > _____________________________
> > > Patrick Luthi
> > > Manager - Technical Standards
> > > Rapporteur (chairman) for the ITU-T multimedia systems,
> terminals and
> > > data-conferencing Experts group (Question 1/16)
> > > TANDBERG
> > > N-1366 Lysaker, Norway
> > > Phone: + 47 67 125 125
> > > e-mail: patrick.luthi at tandberg.no
> > >
>

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