ENUM -- Telephone Number Mapping A. Mayrhofer
Working Group enum.at
Internet-Draft August 03, 2006
Expires: February 4, 2007
IANA Registration for vCard Enumservice
draft-ietf-enum-vcard-03
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Copyright Notice
Copyright (C) The Internet Society (2006).
Abstract
This memo registers the Enumservice "vCard" with the subtypes
"plain", "xml" and "rdf" using the URI schemes "http" and "https"
according to the IANA Enumservice registration process described in
RFC 3761. This Enumservice is to be used to refer from an ENUM
domain name to a vCard instance describing the user of the respective
E.164 number.
Information gathered from those vCards could be used before, during
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or after inbound or outbound communication takes place. For example,
a callee might be presented with the name and association of the
caller before picking up the call.
Table of Contents
1. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. ENUM Service Registrations - vCard . . . . . . . . . . . . . . 4
3.1. "Plain" Subtype . . . . . . . . . . . . . . . . . . . . . 4
3.2. "RDF" Subtype . . . . . . . . . . . . . . . . . . . . . . 5
3.3. "XML" Subtype . . . . . . . . . . . . . . . . . . . . . . 5
4. Example . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5. Security & Privacy Considerations . . . . . . . . . . . . . . 6
5.1. The ENUM Record Itself . . . . . . . . . . . . . . . . . . 6
5.2. The Resource Identified . . . . . . . . . . . . . . . . . 6
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 7
7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 7
8. Normative References . . . . . . . . . . . . . . . . . . . . . 7
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 9
Intellectual Property and Copyright Statements . . . . . . . . . . 10
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1. Change Log
[Note to editors: This section is to be removed before publication -
XML source available on request]
draft-ietf-enum-vcard-03
Fixed typo in abstract
Added acks
Added text about PII data
draft-ietf-enum-vcard-02
added Acknowledgement section
clarified security considerations
extended introduction
sanitized references
added subtypes and URI schemes to Abstract
draft-ietf-enum-vcard-01
minor title change
removed sink type
draft-ietf-enum-vcard-00
changed name to reflect WG adoption
subtyped Enumservice
added "sink" type idea
worked on the text
draft-mayrhofer-enum-vcard-00
initial draft
2. Introduction
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [8].
E.164 Number Mapping (ENUM) [1] uses the Domain Name System (DNS) [2]
to refer from E.164 numbers [3] to Uniform Resource Identifiers
(URIs) [5]. The registration process for Enumservices is described
in section 3 of RFC 3761.
"vCard" [6] is a transport independent data format for the exchange
of information about an individual. For the purpose of this
document, the term "vCard" refers to a specific instance of this data
format - an "electronic business card". vCards are exchanged via
several protocols, most commonly they are distributed as electronic
mail attachments or published on web servers. Most popular personal
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information manager applications are capable of reading and writing
vCards.
In addition to the format specified in RFC 2426, 'Representing vCard
Objects in RDF/XML' [4] specifies two alternative formats for
representing vCard data, namely as RDF or "plain" XML documents.
The Enumservice specified in this document deals with the relation
between an E.164 number and vCards. An ENUM record using this
Enumservice identifies a resource from where a vCard corresponding to
the respective E.164 number could be fetched. Each subtype of the
Enumservice corresponds to one of the vCard data formats mentioned
above.
Clients could use those resources to eg. automatically update local
address books (a Voice over IP phone could try to fetch vCards for
all outbound and inbound calls taking place on that phone and display
them together with the call journal). In a more integrated scenario,
Information gathered from those vCards could even be automatically
incorporated into the personal information manager application of the
respective user.
3. ENUM Service Registrations - vCard
3.1. "Plain" Subtype
Enumservice Name: "vCard"
Enumservice Type: "vcard"
Enumservice Subtype: "plain"
URI Schemes: "http", "https"
Functional Specification:
This Enumservice indicates that the resource identified is a plain
vCard according to RFC 2426 which may be accessed using HTTP/HTTPS
[7].
Clients fetching the vCard from the resource indicated should
expect access to be restricted. Additionally, the comprehension
of the data provided may vary depending on the client's identity.
Security Considerations: see Section 5
Intended Usage: COMMON
Authors: Alexander Mayrhofer (see "Author's Address" section for
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contact details)
3.2. "RDF" Subtype
Enumservice Name: "vCard"
Enumservice Type: "vcard"
Enumservice Subtype: "rdf"
URI Schemes: "http", "https"
Functional Specification:
This Enumservice indicates that the resource identified is a RDF-
formatted vCard according to section 3 - 5 of W3C vcard-rdf [4]
which may be accessed using HTTP/HTTPS.
Clients fetching the vCard from the resource indicated should
expect access to be restricted. Additionally, the comprehension
of the data provided may vary depending on the client's identity.
Security Considerations: see Section 5
Intended Usage: COMMON
Authors: Alexander Mayrhofer (see "Author's Address" section for
contact details)
3.3. "XML" Subtype
Enumservice Name: "vCard"
Enumservice Type: "vcard"
Enumservice Subtype: "xml"
URI Schemes: "http", "https"
Functional Specification:
This Enumservice indicates that the resource identified is a XML-
formatted vCard according to section 6 of W3C vcard-rdf [4] which
may be accessed using HTTP/HTTPS.
Clients fetching the vCard from the resource indicated should
expect access to be restricted. Additionally, the comprehension
of the data provided may vary depending on the client's identity.
Security Considerations: see Section 5
Intended Usage: COMMON
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Authors: Alexander Mayrhofer (see "Author's Address" section for
contact details)
4. Example
An example ENUM entry referencing to a plain vCard could look like:
$ORIGIN 4.3.6.1.4.6.5.0.5.1.3.4.e164.arpa.
@ IN NAPTR 100 10 "u" "E2U+vcard:plain"
"!^.*$!http://example.com/vcard-alex.vcf!" .
5. Security & Privacy Considerations
5.1. The ENUM Record Itself
Since ENUM uses DNS - a publicly available database - any information
contained in records provisioned in ENUM domains must be considered
public as well. Even after revoking the DNS entry and removing the
refered resource, copies of the information could still be available.
Information published in ENUM records could reveal associations
between E.164 numbers and their owners - especially if URIs contain
personal identifiers or domain names for which ownership information
can be obtained easily.
However, it is important to note that the ENUM record itself does not
need to contain any personal information. It just points to a
location where access to personal information could be granted.
ENUM records pointing to third party resources can easily be
provisioned on purpose by the ENUM domain owner - so any assumption
about the association between a number and an entity could therefore
be completely bogus unless some kind of identity verification is in
place. This verification is out of scope for this memo.
5.2. The Resource Identified
In most cases, vCards provide information about individuals. Linking
telephone numbers to such Personally Identifyable Information (PII)
is a very sensitive topic, because it provides a "reverse lookup"
from the number to its owner. Publication of such PII is covered by
data protection law in many legislations. In most cases, the
explicit consent of the affected individual is required.
Users MUST therefore carefully consider information they provide in
the resource identified by the ENUM record as well as in the record
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itself. Considerations SHOULD include serving information only to
entities of the user's choice and/or limiting the comprehension of
the information provided based on the requesting entity.
On the other hand, most of the information which a vCard would
typically contain is already available via more "traditional" sources
like white pages and offline/online directories, especially if those
resources already allow "reverse lookups" (using phone numbers as the
search key). In such cases, publishing a vCard on the internet and
associating it to a phone number does not neccessarily increase the
amount of available information. It may, however, ease access to
this information (which is actually the intention of this Enumservice
in the first place).
If access restrictions on the vCard resource are deployed, Standard
HTTP mechanisms MUST be used to enforce those restrictions. HTTPS
SHOULD be preferred if the deployed mechanisms are prone to
eavesdropping and replay attacks.
6. IANA Considerations
This memo requests registration of the "vCard" Enumservice according
to the definitions in this document and RFC 3761 [1].
7. Acknowledgements
The author wishes to thank David Lindner for his contributions during
the early stages of this document. In addition, Klaus Nieminen and
Ondrej Sury provided helpful suggestions.
8. Normative References
[1] Faltstrom, P. and M. Mealling, "The E.164 to Uniform Resource
Identifiers (URI) Dynamic Delegation Discovery System (DDDS)
Application (ENUM)", RFC 3761, April 2004.
[2] Mockapetris, P., "Domain names - Implementation and
Specification", STD 13, RFC 1035, November 1987.
[3] ITU-T, "The international public telecommunication numbering
plan", Recommendation E.164 (02/05), Feb 2005.
[4] Iannella, R., "Representing vCard Objects in RDF/XML", W3C
NOTE NOTE-vcard-rdf-20010222, February 2001.
[5] Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
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Resource Identifier (URI): Generic Syntax", STD 66, RFC 3986,
January 2005.
[6] Dawson, F. and T. Howes, "vCard MIME Directory Profile",
RFC 2426, September 1998.
[7] Fielding, R., Gettys, J., Mogul, J., Frystyk, H., Masinter, L.,
Leach, P., and T. Berners-Lee, "Hypertext Transfer Protocol --
HTTP/1.1", RFC 2616, June 1999.
[8] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997.
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Author's Address
Alexander Mayrhofer
enum.at GmbH
Karlsplatz 1/9
Wien A-1010
Austria
Phone: +43 1 5056416 34
Email: alexander.mayrhofer@enum.at
URI: http://www.enum.at/
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