Re: [Geopriv] draft-ietf-geopriv-lbyr-requirements-02 comments

From: Roger Marshall ^lt;RMarshall@telecomsys.com>
Date: Wed Jul 30 2008 - 09:21:15 EDT

Martin:
Thanks very much for these comments. These have remained on the list
now for a few weeks with no objections (that have not been resolved).
Since I too have no objection to anything I see here, and presuming no
major objections based on tomorrow's status update in the geopriv
meeting, I plan to fold these changes in, rev the draft, and recommend
to the wg chairs that the doc go to WGLC.

-roger marshall.

> -----Original Message-----
> From: Thomson, Martin [mailto:Martin.Thomson@andrew.com]
> Sent: Wednesday, July 09, 2008 9:38 PM
> To: Roger Marshall
> Cc: GEOPRIV
> Subject: RE: [Geopriv]
> draft-ietf-geopriv-lbyr-requirements-02 comments
>
> {S} New comment: a location URI, by necessity, indicates the
> server that hosts the location information. This could
> reveal something about the location of the Target. This is
> probably worthwhile noting as a security consideration. This
> can be addressed, as with any other problem in this domain,
> by another layer of indirection: namely the use of a (remote)
> presence server.
>
> > -----Original Message-----
> > From: geopriv-bounces@ietf.org [mailto:geopriv-bounces@ietf.org] On
> > Behalf Of Thomson, Martin
> > Sent: Thursday, 10 July 2008 11:12 AM
> > To: Roger Marshall
> > Cc: GEOPRIV
> > Subject: [Geopriv] draft-ietf-geopriv-lbyr-requirements-02 comments
> >
> > Hi Roger,
> >
> > I have quite a few editorial comments. I apologise if this
> seems like
> > a lot; I'm just suggesting a little restructuring to improve
> > readability.
> >
> > I have a few substantive comments (marked with {S}), but they are
> > minor.
> >
> > Based on my reading, I'd be happy to see this document
> published. It
> > would be good to be able to dispense with this particular Dec 2007
> > milestone.
> >
> > Cheers,
> > Martin
> >
> > ~~~
> >
> > Section 1:
> >
> > It's unclear what the intent of the list in the introduction is.
> > From the lead-in, it appears to be enumerating the uses of
> a location
> > reference; the ways that a location URI provides benefit. However,
> > from points 2, 3 and 4, it appears to be describing behaviour.
> > I can't quite work out whether you intended there to be a
> > distinction between point 1 and 2; if it was to separate
> creation from
> > distribution, then I'm not sure that this is the correct way to
> > present it.
> >
> > If the intent is to avoid discussion of possible
> uses/benefits of a
> > location reference, it might just be best to introduce this as the
> > "lifecycle" of a location reference.
> > Creation
> > Dissemination
> > Distribution (conveyance)
> > Dereference
> > Expiry/cancellation
> > Based on this you can then move to set the scope of the document.
> > Note that creation, dissemination and cancellation/expiration fall
> > under the auspices of location configuration protocols; dereference
> > protocols for dereference; point out that conveyance is already
> > adequately covered, so it wont be described in detail by
> the document.
> > I don't think that any of this is missing, but I found it
> hard to get
> > this without reading this bit over a couple of times.
> >
> > You can refer to draft-ietf-geopriv-l7-lcp-ps for the
> definition of
> > 'LIS', as you do for RFC 3693 and 'LS'. (Something for Section 2,
> > which needs a definition for LIS)
> >
> > Section 3:
> >
> > The first paragraph and the first part of the second paragraph of
> > this section might be better suited to Section 1. Section 1 lacks
> > discussion on the motivation for this mechanism.
> >
> > The second part of the second paragraph (discussion of dereference
> > protocols) would fit quite nicely with the discussion of
> configuration
> > protocols from Section 1.
> >
> > If you move those, the section intro looks bare. A vague/generic
> > introduction statement will probably suffice: "This section
> describes
> > the entities and interactions ,etc...."
> >
> > Your caption on Figure 1 is strange - the text is repeated on the
> > next paragraph. I assume that you intended something else
> here. (for
> > the XML format, you only need to use <figure anchor="arch"
> > title="Location Reference Entities and Interactions">... and <xref
> > target="arch"/>)
> >
> > Note B: s/authorize anything of than/authorize anything
> other than/
> >
> > Note C: s/Note C. that the/Note C. The/
> >
> > Next paragraph: extraneous comma: s/via HELD, (/via HELD (/
> >
> > {S} Where you say that a geospatial boundary can be
> expressed to get
> > an updated location when it crosses a boundary, you
> reference geopriv-
> > policy. While it is possible to use policy to restrict access to
> > location information based on its value, policy cannot cause a
> > notification to be sent once the condition is met. This is another
> > use for loc-filters.
> >
> > {S} Next paragraph: Justification for expiry needs to include
> > security. This is the primary use, particularly where
> references use
> > the "possession" model. Expiry limits the time that accidental
> > leaking of a URI causes. (from a requirements perspective I tend
> > towards a MUST use, but would be happy with SHOULD use and
> MUST implement - c.f.
> > HELD design). I have another comment on Section 4 on this topic.
> >
> > Your statement on "access control" and "possession" states a
> > requirement: "Dereference protocols must support both types." It's
> > probably not necessary to put this here (ahead of D11).
> >
> > I don't like the terms you've used for "use types". The
> terms that
> > used in draft-winterbottom-geopriv-deref-protocol (which
> was long ago
> > agreed as a WG item) are better. "authorization model" is good:
> > "possession authorization model" and "access control authorization
> > model" are clearer and consistent with the other work.
> >
> > {S} Your discussion of the Access control use type seems to imply
> > that the LIS applies authentication and authorization on
> the location
> > configuration protocol. This isn't necessary - what it
> necessary is
> > that the rule maker (owner/target) is able to provide authorization
> > policies to the LIS during this stage, or through some
> other parallel
> > mechanism (your interface 1b). In fact, I would shift the
> focus from
> > the LCP at this stage to concentrate on how policies are
> attached to a
> > reference through an (undisclosed) mechanism.
> >
> > The paragraph after the two "use types" shouldn't be indented.
> >
> > Section 4:
> >
> > {S} C3: For the possession model, this requirement is a MUST.
> >
> > {S} In addition to requirement C2 and C3, I'd like to see
> a SHOULD-
> > strength requirement on expiry time. Again, for the possession
> > authorization model, this is a MUST. The motivation for
> this is the
> > similar to that for cancellation: the time that a reference can be
> > used needs by unknown attackers needs to be limited. If a user's
> > LocURI gets leaked to an attacker, with an expiration time, the
> > exposure is limited.
> >
> > {Semi-S} C8: change the name to "Location Only".
> >
> > {S} C7 and D6: These requirements pre-suppose a protocol
> > implementation, namely that expiration needs to be indicated in
> > relative terms. (It also pre-supposes that people prefer
> seconds over
> > other units, like microfortnights.) I'd prefer the following
> > requirement:
> > A configuration/dererefence protocol MUST provide an
> indication of
> > the expiry time (or validity interval) for a location URI.
> > (Absolute and relative both have drawbacks. Absolute
> suffers from
> > problems when clocks are out of sync; relative time suffers from a
> > period of uncertainty at the end of the interval due to the
> receiver
> > not knowing when the interval started. I prefer absolute,
> but I can
> > appreciate how relative time indications use fewer bits.)
> >
> > {S} C11 and D11: Time saving is nice, but this isn't a hard
> > requirement. These are SHOULD requirements.
> >
> > Section 5:
> >
> > Remove the lead-in sentence.
> >
> > Remove the "pawn ticket" reference and refer to the possession
> > authorization model instead.
> >
> >
> > ~~
> >
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Received on Wed, 30 Jul 2008 06:21:15 -0700

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