WG Review: Internationalized Domain Names in Applications
iesg-secretary at ietf.org
Thu Apr 3 01:00:01 CEST 2008
A new IETF working group has been proposed in the Applications Area. The
IESG has not made any determination as yet. The following draft charter
was submitted, and is provided for informational purposes only. Please
send your comments to the IESG mailing list (iesg at ietf.org) by Wednesday,
April 9, 2008.
Internationalized Domain Names in Applications (Revised) (idnabis)
Last modified: 2008-03-31
Current Status: Proposed Working Group
Applications Area Directors:
Lisa Dusseault (ldusseault at commerce.net)
Chris Newman (Chris.Newman at sun.com)
Applications Area Advisor:
Lisa Dusseault (ldusseault at commerce.net)
General Discussion: idna-update at alvestrand.no
To Subscribe: http://www.alvestrand.no/mailman/listinfo/idna-update
The original Internationalized Domain Name (IDN) WG specified rules
for the use of characters other than Latin A(a)-Z(z), digits 0-9 and the
hyphen (-) in domain names in RFC3490, RFC3491 and RFC3492 in 2002
(published in 2003 and often referenced collectively as IDNA2003).
These documents depend on RFC 3454 and were tied to Unicode version 3.2.
An update to the current version (5.x) is required to accommodate
additional scripts. In addition, experience has shown that significant
improvements could be made in the protocol as presently specified.
This WG is chartered to decouple IDNA from specific versions of Unicode
using algorithms that define validity based on Unicode properties. It is
recognized that some explicit exceptions may be necessary in any case, but
attempts will be made to minimize these exceptions.
- Separate requirements for valid IDNs at registration time (insertion
of names into DNS zone files), vs. at resolution time (looking up those
- Review, and if necessary revise, the algorithms and rules for handling
right to left character sequences in an IDN context to allow labels based
on additional scripts and languages and to make presentation as
predictable as reasonably possible.
- Permit use of some scripts that were inadvertently excluded by the
- Ensure practical stability of validity algorithms for IDNs.
The constraints of the original IDN WG still apply to IDNABIS, namely to
avoid disturbing the current use and operation of the domain name system,
and for the DNS to continue to allow any system to resolve any domain name
in a consistent way. The client-based approach of the original IDN work
will be maintained -- substantially new protocols or mechanisms are not in
scope. In particular, IDNs continue to use the "xn--" prefix and the same
ASCII-compatible encoding, and the bidirectional algorithm follows the
same basic design.
The specifications are initially organized as four documents: overview
and rationale, protocol, table algorithm, and improvements to the
bidirectional algorithm. These documents are to be used as the basis for
the discussion of the general direction of the work.
This working group will be providing extended public review of the output
of a design team that has been working on improvement of the IDNA
This review-based approach is being used in part because of the way the
work was undertaken by the team; in particular, the design team has been
working with IETF visibility and has solicited and received significant
amounts of technical review already from IETF participants and from others
including experts in the Unicode specifications and the use of scripts in
languages. If the public review provided by this Working Group confirms
the basic method outlined in the input documents, it is expected that the
working group will be able to respond with any needed changes and close in
a short period of time. If technical issues arise that indicate a
fundamentally different approach must be taken from the one outlined
above, it is anticipated that this working group would close, and a new
one with an appropriate charter would be considered.
This work is intended to specify an improved means to produce and use
stable and unambiguous IDN identifiers.
There are a variety of generally unsolvable problems, notably the problem
of characters that are confusingly similar in appearance (often known as
the "phishing" problem) that are not specifically part of the scope of the
WG although some of the preliminary results of the design team suggest
that the improvements contemplated in the specifications might
mitigate some of the ways in which the current IDNA specifications can be
abused for phishing purposes.
While it is referenced from the original IDNA2003 package, the original
Stringprep specification, RFC 3454, is not formally part of the IDNA
package and will not be altered by this work.
The work will update or obsolete RFC 3490. It is not expected to
continue to use Nameprep (RFC 3491). Nameprep is used by other
specifications; determining how (or whether) to update those
specifications and, consequently, the long-term status of Nameprep, are
not part of this effort. The method for ASCII-compatible ("ACE") encoding
of IDNs, "Punycode" (RFC 3492) will not be revised by this WG.
Subject to the more general constraints described above, the WG is
permitted to consider changes that are not strictly backwards-compatible.
For any such change that is recommended, it is expected to document the
reasons for the change, the characters affected, and possible transition
The assumptions outlined above are considered critical to the WG
constituted by this charter. The WG will stop work and recommend that a
new charter be generated if it concludes that any of the following are
necessary to meet its goals:
(i) A change to the "punycode" algorithm or to the ACE approach to
encoding names in the DNS.
(ii) A change to the ACE prefix from "xn--"
(iii) A change to the basic approach taken in the design team documents
(Namely: independence from Unicode version and elimination of character
mapping in the protocol)
Goals and milestones:
Apr 08: WG formation
May 08: Decision on form and structure of the WG document set
Sep 08: WG Last Call on WG document set
Nov 08: IETF Last Call on WG document set
More information about the Idna-update