Internationalized Domain Names in Applications (Revised) (idnabis)

Last Modified: 2008-04-15

Additional information is available at tools.ietf.org/wg/idnabis

Chair(s):

  • Vinton Cerf <vint@google.com>

    Applications Area Director(s):

  • Chris Newman <chris.newman@sun.com>
  • Lisa Dusseault <lisa@osafoundation.org>

    Applications Area Advisor:

  • Lisa Dusseault <lisa@osafoundation.org>

    Mailing Lists:

    General Discussion: idna-update@alvestrand.no
    To Subscribe: http://www.alvestrand.no/mailman/listinfo/idna-update
    Archive: http://www.alvestrand.no/pipermail/idna-update/

    Description of Working Group:

    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.

    Additional goals:

      - Separate requirements for valid IDNs at registration time (insertion
    of names into DNS zone files), vs. at resolution time (looking up those
    names)
      - 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
    original protocols.
      - 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
    specifications.

    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 strategies.

    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 2008  WG formation
    May 2008  Decision on form and structure of the WG document set
    Sep 2008  WG Last Call on WG document set
    Nov 2008  IETF Last Call on WG document set

    Internet-Drafts:

    The Unicode Codepoints and IDNA (167402 bytes)
    Internationalized Domain Names for Applications (IDNA): Definitions, Background and Rationale (132881 bytes)
    Internationalized Domain Names in Applications (IDNA): Protocol (62226 bytes)
    An updated IDNA criterion for right-to-left scripts (40668 bytes)

    No Request For Comments

    IETF Secretariat - Please send questions, comments, and/or suggestions to ietf-web@ietf.org.

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