Subject: [Ecrit] Additional data

From: Martin Thomson <[email-masked]>
Date: Sat, 24 Mar 2012 16:51:02 -0700

Emergency authorities might request a great range of information.
Some of that information might be illegal to provide in some
jurisdictions, while mandatory in others.  All that this specification
can do is provide the framework for the inclusion of arbitrary data.

The few examples that are included need to be generic enough to
satisfy the needs of all jurisdictions.  That should not prevent an
organization from registering new MIME types, adding elements to the
existing structures, or even choosing to use entirely different
formats.  What is not clear from the draft is that these things are
possible.  A small section on extension might help.

The discussion in the security considerations section is a little
strange.  There is already a global PKI infrastructure sufficient for
the authentication of HTTPS.  Unless the intent is to establish a
parallel PKI infrastructure, the paragraph could be a little cleaner.
Information that is provided by reference MUST be provided using a
mechanism that supports confidentiality.  Ensuring that access to
information is only provided to emergency services depends on client
authentication and the provision of access control policies.  This
document does not attempt to solve the very difficult problem of
client authentication and authorization, but it could do something. If
HTTPS URIs contained a per-call authentication token that was
difficult to guess (in the path component, for example), then it would
only be possible to access this information if the signaling were
seen.  That gives equivalent protection to those parts that are in the
body of the request.

The privacy considerations section is weak.  SHOULD NOT send when
attached to this much of a potential violation of privacy could be
made a lot stronger.  I suspect that taking a closer look at whether
the call is actually an emergency call in the first place would be a
good place to start.  The security section is much stronger on this
point: This additional information MUST NOT be included unless the
call is an emergency call and the inclusion of the additional data is
mandated by an appropriate authority.  If there are cases where it is
not certain that a call is emergency or not when making this
determination, then the information MAY be provided.

A few nits:
MIME types are incomplete in most places. When defined, the full MIME
media type should be used to eliminate ambiguity, e.g.,
"application/addCallSvcInfo+xml".
The language tag should refer to the applicable RFC for language tags, RFC 5646.

--Martin