Re: [dns-privacy] I-D Action: draft-ietf-dprive-padding-policy-01.txt

[Hugo Connery <[e-mail]>]

Hi Alexander (and list),

Thanks, Alexander, for your efforts on the document
(and DKG for the empirical work).

May I suggest that another strategy is included, that of 
"always pad to the maximum message size".  This is obviously
wasteful, and may be recommended against.  However, I believe
its inclusion is equivalent to the "no padding" and "fixed
block size pad" options which are listed for completeness whilst
providing no or very little privacy protection.

The "always pad to maximum message size" option is actually 
the maximal privacy setting (when encrypted) but is horribly
wasteful.

Perhaps mention it directly after the "no padding option" and
describe that it provides maximal privacy protection, but is 
wasteful and more balanced strategies are described below,
including the recommended strategy.

Something like this:

---

4.2 Maximal Length Padding

In maximal length padding the sender pads every message to the
maximum allowed size for a message.

Advantages: Maximal length padding, when combined with encrypted
transport, provides the highest level of privacy protection.

Disadvantages: Maximal length padding places a heavy burden on all
parties, including the client, all intervening network equipment, and
the server.

Maximal length padding is not a recommended strategy.

---

Regards,  Hugo Connery


On Mon, 2017-07-03 at 23:29 +0200, Alexander Mayrhofer wrote:
> Hi,
> 
> i've updated the Padding Policy draft - the main change is the
> inclusion of an actual recommendation, essentially a blunt copy of
> Daniel's recommendations from his empirical research work.
> 
> I'm looking forward to hearing a discussion around these
> recommendations - I will subsequently update the draft based on the
> outcome of those discussions.
> 
> best,
> Alex
> 
> 
> On Mon, Jul 3, 2017 at 11:25 PM, <[e-mail]> wrote:
> > A New Internet-Draft is available from the on-line Internet-Drafts
> > directories.
> > This draft is a work item of the DNS PRIVate Exchange of the IETF.
> > 
> >         Title           : Padding Policy for EDNS(0)
> >         Author          : Alexander Mayrhofer
> >         Filename        : draft-ietf-dprive-padding-policy-01.txt
> >         Pages           : 7
> >         Date            : 2017-07-03
> > 
> > Abstract:
> >    RFC 7830 specifies the EDNS0 'Padding' option, but does not
> > specify
> >    the length of padding to be used in specific applications.  This
> > memo
> >    lists the possible options ("Padding Policies"), discusses the
> >    implications of each of these options, and provides a
> > recommended
> >    option.
> > 
> > 
> > The IETF datatracker status page for this draft is:
> > https://datatracker.ietf.org/doc/draft-ietf-dprive-padding-policy/
> > 
> > There are also htmlized versions available at:
> > https://tools.ietf.org/html/draft-ietf-dprive-padding-policy-01
> > https://datatracker.ietf.org/doc/html/draft-ietf-dprive-padding-pol
> > icy-01
> > 
> > A diff from the previous version is available at:
> > https://www.ietf.org/rfcdiff?url2=draft-ietf-dprive-padding-policy-
> > 01
> > 
> > 
> > Please note that it may take a couple of minutes from the time of
> > submission
> > until the htmlized version and diff are available at
> > tools.ietf.org.
> > 
> > Internet-Drafts are also available by anonymous FTP at:
> > ftp://ftp.ietf.org/internet-drafts/
> > 
> > _______________________________________________
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> > https://www.ietf.org/mailman/listinfo/dns-privacy
> 
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