[Docs] [txt|pdf|xml|html] [Tracker] [WG] [Email] [Diff1] [Diff2] [Nits]

Versions: (draft-saintandre-precis-nickname) 00 01 02 03 04 05 06 07 08 09 10 11 12 13 14 15 16 17 18 19 RFC 7700

PRECIS                                                    P. Saint-Andre
Internet-Draft                                       Cisco Systems, Inc.
Intended status: Standards Track                      September 20, 2012
Expires: March 24, 2013


                Preparation and Comparison of Nicknames
                     draft-ietf-precis-nickname-01

Abstract

   This document describes how to prepare and compare Unicode strings
   representing nicknames, primarily as used within textual chatrooms.
   This profile is intended to be used by chatroom technologies based on
   both the Message Session Relay Protocol (MSRP) and the Extensible
   Messaging and Presence Protocol (XMPP).

Status of this Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF).  Note that other groups may also distribute
   working documents as Internet-Drafts.  The list of current Internet-
   Drafts is at http://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
   and may be updated, replaced, or obsoleted by other documents at any
   time.  It is inappropriate to use Internet-Drafts as reference
   material or to cite them other than as "work in progress."

   This Internet-Draft will expire on March 24, 2013.

Copyright Notice

   Copyright (c) 2012 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.



Saint-Andre              Expires March 24, 2013                 [Page 1]


Internet-Draft               PRECIS Nickname              September 2012


Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.1.  Overview  . . . . . . . . . . . . . . . . . . . . . . . . . 3
     1.2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
   2.  Rules . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3
   3.  Security Considerations . . . . . . . . . . . . . . . . . . . . 4
     3.1.  Reuse of PRECIS . . . . . . . . . . . . . . . . . . . . . . 5
     3.2.  Reuse of Unicode  . . . . . . . . . . . . . . . . . . . . . 5
     3.3.  Visually Similar Characters . . . . . . . . . . . . . . . . 5
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5
   5.  References  . . . . . . . . . . . . . . . . . . . . . . . . . . 5
     5.1.  Normative References  . . . . . . . . . . . . . . . . . . . 5
     5.2.  Informative References  . . . . . . . . . . . . . . . . . . 6
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . . . 7




































Saint-Andre              Expires March 24, 2013                 [Page 2]


Internet-Draft               PRECIS Nickname              September 2012


1.  Introduction

1.1.  Overview

   Technologies for textual chatrooms customarily enable participants to
   specify a nickname for use in the room; e.g., this is true of
   Internet Relay Chat [RFC2811], Multi-User Chat (MUC) based on the
   Extensible Messaging and Presence Protocol (XMPP) [XEP-0045], and
   multi-party chat based on the Message Session Relay Protocol (MSRP)
   [I-D.ietf-simple-chat].  Recent chatroom technologies also allow
   internationalized nicknames because they support characters from
   outside the ASCII range [RFC20], typically by means of the Unicode
   character set [UNICODE].  Although such nicknames tend to be used
   primarily for display purposes, they are sometimes used for
   programmatic purposes as well (e.g., kicking users or avoiding
   nickname conflicts).

   To increase the likelihood that nicknames will work in ways that make
   sense for typical users throughout the world, this document defines
   rules for preparing and comparing internationalized nicknames.

1.2.  Terminology

   Many important terms used in this document are defined in
   [I-D.ietf-precis-framework], [RFC6365], and [UNICODE].  Relevant XMPP
   terms are defined in [RFC6120] and [XEP-0045], and relevant MSRP
   terms are defined in [RFC4975] and [I-D.ietf-simple-chat].

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in RFC
   2119 [RFC2119].


2.  Rules

   A nickname MUST consist only of Unicode code points that conform to
   the "FreeClass" base string class defined in
   [I-D.ietf-precis-framework].

   For preparation purposes (most commonly, when a chatroom client
   generates a nickname from user input for inclusion as a protocol
   element that represents a "nickname slot"), an application MUST at a
   minimum ensure that the string conforms to the "FreeClass" base
   string class defined in [I-D.ietf-precis-framework]; however, it MAY
   in addition perform the normalization and mapping operations
   specified below for comparison purposes.




Saint-Andre              Expires March 24, 2013                 [Page 3]


Internet-Draft               PRECIS Nickname              September 2012


   For comparison purposes (e.g., when a chatroom server determines if
   two nicknames are in conflict during the authorization process), an
   application MUST treat a nickname as follows, where the operations
   specified MUST be completed in the order shown (in particular,
   normalization MUST be performed before all other mapping steps and
   validity checks, consistent with [I-D.ietf-precis-framework]):

   1.  The string MUST be normalized using Unicode Normalization Form KC
       (NFKC).  Because NFKC is more "aggressive" in finding matches
       than other normalization forms (in the terminology of Unicode, it
       performs both canonical and compatibility decomposition before
       recomposing code points), this rule helps to reduce the
       possibility of confusion by increasing the number of characters
       that would match (e.g., U+2163 ROMAN NUMERAL FOUR would match the
       combination of U+0049 LATIN CAPITAL LETTER I and U+0056 LATIN
       CAPITAL LETTER V).

   2.  Uppercase and titlecase characters MUST be mapped to their
       lowercase equivalents.  In applications that prohibit conflicting
       nicknames, this rule helps to reduce the possibility of confusion
       by ensuring that nicknames differing only by case (e.g.,
       "stpeter" vs. "StPeter") would not be allowed in a chatroom at
       the same time.

   3.  Non-ASCII space characters from the "N" category defined under
       Section 6.14 of [I-D.ietf-precis-framework] MUST be mapped to
       U+0020 SPACE.

   4.  Other mappings MAY be applied, such as those defined in
       [I-D.yoneya-precis-mappings].  (Note that mapping of fullwidth
       and halfwidth characters to their decomposition mappings is not
       necessary, since those mappings are performed as part of
       normalization using NFKC.)

   For both preparation and comparison, the "Bidi Rule" defined in
   [RFC5893] applies to the directionality of a nickname.

   After all of the foregoing rules have been applied, a nickname MUST
   NOT be zero bytes in length and MUST NOT be more than 1023 bytes in
   length (the latter restriction is derived from the length restriction
   on XMPP resourceparts, see [RFC6122]).


3.  Security Considerations







Saint-Andre              Expires March 24, 2013                 [Page 4]


Internet-Draft               PRECIS Nickname              September 2012


3.1.  Reuse of PRECIS

   The security considerations described in [I-D.ietf-precis-framework]
   apply to the "FreeClass" base string class used in this document for
   nicknames.

3.2.  Reuse of Unicode

   The security considerations described in [UTR39] apply to the use of
   Unicode characters in nicknames.

3.3.  Visually Similar Characters

   Section 10.5 of [I-D.ietf-precis-framework] describes some of the
   security considerations related to visually similar characters, also
   called "confusable characters" or "confusables".

   Although the mapping rules defined under Section 2 of this document
   are designed in part to reduce the possibility of confusion about
   nicknames, this document does not provide more detailed
   recommendations regarding the handling of visually similar
   characters, such as those in [UTR39].


4.  IANA Considerations

   The IANA shall add an entry to the PRECIS Usage Registry for reuse of
   the PRECIS FreeClass in the preparation and comparison of nicknames.

   Application Protocol(s):  MSRP and XMPP.
   Base Class:  FreeClass.
   Subclassing:  No.
   Normalization:  NFKC.
   Casemapping:  Map uppercase and titlecase characters to lowercase.
   Additional Mappings:  Map non-ASCII space characters to ASCII space.
   Directionality:  The "Bidi Rule" defined in RFC 5893 applies.
   Specification:  RFC XXXX.


5.  References

5.1.  Normative References

   [I-D.ietf-precis-framework]
              Saint-Andre, P. and M. Blanchet, "Precis Framework:
              Handling Internationalized Strings in Protocols",
              draft-ietf-precis-framework-05 (work in progress),
              August 2012.



Saint-Andre              Expires March 24, 2013                 [Page 5]


Internet-Draft               PRECIS Nickname              September 2012


   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC5893]  Alvestrand, H. and C. Karp, "Right-to-Left Scripts for
              Internationalized Domain Names for Applications (IDNA)",
              RFC 5893, August 2010.

   [UNICODE]  The Unicode Consortium, "The Unicode Standard, Version
              6.1", 2012,
              <http://www.unicode.org/versions/Unicode6.1.0/>.

   [UTR39]    The Unicode Consortium, "Unicode Technical Report #39:
              Unicode Security Mechanisms", August 2010,
              <http://unicode.org/reports/tr39/>.

5.2.  Informative References

   [I-D.ietf-simple-chat]
              Niemi, A., Garcia, M., and G. Sandbakken, "Multi-party
              Chat Using the Message Session Relay Protocol (MSRP)",
              draft-ietf-simple-chat-16 (work in progress), August 2012.

   [I-D.yoneya-precis-mappings]
              YONEYA, Y. and T. NEMOTO, "Mapping characters for PRECIS
              classes", draft-yoneya-precis-mappings-02 (work in
              progress), July 2012.

   [RFC20]    Cerf, V., "ASCII format for network interchange", RFC 20,
              October 1969.

   [RFC2811]  Kalt, C., "Internet Relay Chat: Channel Management",
              RFC 2811, April 2000.

   [RFC4975]  Campbell, B., Mahy, R., and C. Jennings, "The Message
              Session Relay Protocol (MSRP)", RFC 4975, September 2007.

   [RFC6120]  Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Core", RFC 6120, March 2011.

   [RFC6122]  Saint-Andre, P., "Extensible Messaging and Presence
              Protocol (XMPP): Address Format", RFC 6122, March 2011.

   [RFC6365]  Hoffman, P. and J. Klensin, "Terminology Used in
              Internationalization in the IETF", BCP 166, RFC 6365,
              September 2011.

   [XEP-0045]
              Saint-Andre, P., "Multi-User Chat", XSF XEP 0045,



Saint-Andre              Expires March 24, 2013                 [Page 6]


Internet-Draft               PRECIS Nickname              September 2012


              February 2012.


Author's Address

   Peter Saint-Andre
   Cisco Systems, Inc.
   1899 Wynkoop Street, Suite 600
   Denver, CO  80202
   USA

   Phone: +1-303-308-3282
   Email: psaintan@cisco.com






































Saint-Andre              Expires March 24, 2013                 [Page 7]


Html markup produced by rfcmarkup 1.129c, available from https://tools.ietf.org/tools/rfcmarkup/