3 Network Working Group P. Saint-Andre
4 Internet-Draft Jabber Software Foundation
5 Expires: December 3, 2003 J. Hildebrand
10 Nodeprep: A Stringprep Profile for Node Identifiers in XMPP
11 draft-ietf-xmpp-nodeprep-03
15 This document is an Internet-Draft and is in full conformance with
16 all provisions of Section 10 of RFC2026.
18 Internet-Drafts are working documents of the Internet Engineering
19 Task Force (IETF), its areas, and its working groups. Note that other
20 groups may also distribute working documents as Internet-Drafts.
22 Internet-Drafts are draft documents valid for a maximum of six months
23 and may be updated, replaced, or obsoleted by other documents at any
24 time. It is inappropriate to use Internet-Drafts as reference
25 material or to cite them other than as "work in progress."
27 The list of current Internet-Drafts can be accessed at http://
28 www.ietf.org/ietf/1id-abstracts.txt.
30 The list of Internet-Draft Shadow Directories can be accessed at
31 http://www.ietf.org/shadow.html.
33 This Internet-Draft will expire on December 3, 2003.
37 Copyright (C) The Internet Society (2003). All Rights Reserved.
41 This document defines a stringprep profile for node identifiers in
42 the Extensible Messaging and Presence Protocol (XMPP).
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62 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
63 1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
64 1.2 Discussion Venue . . . . . . . . . . . . . . . . . . . . . . . 3
65 1.3 Intellectual Property Notice . . . . . . . . . . . . . . . . . 3
66 2. Character Repertoire . . . . . . . . . . . . . . . . . . . . . 5
67 3. Mapping . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
68 4. Normalization . . . . . . . . . . . . . . . . . . . . . . . . 7
69 5. Prohibited Output . . . . . . . . . . . . . . . . . . . . . . 8
70 6. Bidirectional Characters . . . . . . . . . . . . . . . . . . . 9
71 7. Security Considerations . . . . . . . . . . . . . . . . . . . 10
72 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11
73 Normative References . . . . . . . . . . . . . . . . . . . . . 12
74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12
75 A. Revision History . . . . . . . . . . . . . . . . . . . . . . . 13
76 A.1 Changes from draft-ietf-xmpp-nodeprep-02 . . . . . . . . . . . 13
77 A.2 Changes from draft-ietf-xmpp-nodeprep-01 . . . . . . . . . . . 13
78 A.3 Changes from draft-ietf-xmpp-nodeprep-00 . . . . . . . . . . . 13
79 Intellectual Property and Copyright Statements . . . . . . . . 14
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118 This document, which defines a profile of stringprep (RFC 3454 [1]),
119 specifies processing rules that will enable users to enter
120 internationalized node identifiers in XMPP (see XMPP Core [2]) and
121 have the highest chance of getting the content of the strings
122 correct. These processing rules are intended only for XMPP node
123 identifiers (which are often associated with usernames), and are not
124 intended for arbitrary text.
126 This profile defines the following, as required by RFC 3454 [1]:
128 o The intended applicability of the profile: internationalized node
129 identifiers within XMPP
131 o The character repertoire that is the input and output to
132 stringprep: Unicode 3.2, specified in section 2
134 o The mappings used: specified in section 3
136 o The Unicode normalization used: specified in section 4
138 o The characters that are prohibited as output: specified in section
141 o Bidirectional character handling: specified in section 6
146 This document inherits the terminology defined in XMPP Core [2].
148 The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
149 "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
150 "OPTIONAL" in this document are to be interpreted as described in RFC
155 The authors welcome discussion and comments related to the topics
156 presented in this document. The preferred forum is the
157 <xmppwg@jabber.org> mailing list, for which archives and subscription
158 information are available at <http://www.jabber.org/cgi-bin/mailman/
161 1.3 Intellectual Property Notice
163 This document is in full compliance with all provisions of Section 10
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172 of RFC 2026. Parts of this specification use the term "jabber" for
173 identifying namespaces and other protocol syntax. Jabber[tm] is a
174 registered trademark of Jabber, Inc. Jabber, Inc. grants permission
175 to the IETF for use of the Jabber trademark in association with this
176 specification and its successors, if any.
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228 2. Character Repertoire
230 This profile uses Unicode 3.2 with the list of unassigned code points
231 being Table A.1, both defined in Appendix A of RFC 3454 [1].
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286 This profile specifies mapping using the following tables from RFC
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342 This profile specifies using Unicode normalization form KC, as
343 described in RFC 3454 [1].
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398 This profile specifies prohibiting use of the following tables from
423 In addition, the following Unicode characters are also prohibited:
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452 6. Bidirectional Characters
454 This profile specifies checking bidirectional strings as described in
455 section 6 of RFC 3454 [1].
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508 7. Security Considerations
510 The Unicode and ISO/IEC 10646 repertoires have many characters that
511 look similar. In many cases, users of security protocols might do
512 visual matching, such as when comparing the names of trusted third
513 parties. Because it is impossible to map similar-looking characters
514 without a great deal of context such as knowing the fonts used,
515 stringprep does nothing to map similar-looking characters together
516 nor to prohibit some characters because they look like others.
518 A node identifier can be employed as one part of an entity's address
519 in XMPP. One common usage is as the username of an instant messaging
520 user; another is as the name of a multi-user chat room; and many
521 other kinds of entities could use node identifiers as part of their
522 addresses. The security of such services could be compromised based
523 on different interpretations of the internationalized node
524 identifier; for example, a user entering a single internationalized
525 node identifier could access another user's account information, or a
526 user could gain access to an otherwise restricted chat room or
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564 8. IANA Considerations
566 This is a profile of stringprep. If and when it becomes an RFC, it
567 should be registered in the stringprep profile registry maintained by
570 Name of this profile:
574 RFC in which the profile is defined:
578 Indicator whether or not this is the newest version of the profile:
580 This is the first version of Nodeprep
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622 [1] Hoffman, P. and M. Blanchet, "Preparation of Internationalized
623 Strings ("stringprep")", RFC 3454, December 2002.
625 [2] Saint-Andre, P. and J. Miller, "XMPP Core",
626 draft-ietf-xmpp-core-13 (work in progress), June 2003.
628 [3] Bradner, S., "Key words for use in RFCs to Indicate Requirement
629 Levels", BCP 14, RFC 2119, March 1997.
631 [4] Internet Assigned Numbers Authority, "Internet Assigned Numbers
632 Authority", January 1998, <http://www.iana.org/>.
638 Jabber Software Foundation
640 EMail: stpeter@jabber.org
641 URI: http://www.jabber.org/people/stpeter.php
647 EMail: jhildebrand@jabber.com
648 URI: http://www.jabber.org/people/hildjj.php
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676 Appendix A. Revision History
678 Note to RFC Editor: please remove this entire appendix, and the
679 corresponding entries in the table of contents, prior to publication.
681 A.1 Changes from draft-ietf-xmpp-nodeprep-02
683 o Provided additional examples of node identifier usage.
685 o Made several small editorial changes.
688 A.2 Changes from draft-ietf-xmpp-nodeprep-01
690 o Made small editorial changes to address RFC Editor requirements.
693 A.3 Changes from draft-ietf-xmpp-nodeprep-00
695 o Clarified references to Unicode 3.2 and unassigned code points.
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732 Intellectual Property Statement
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751 this standard. Please address the information to the IETF Executive
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