3 Network Working Group P. Saint-Andre
4 Internet-Draft Jabber Software Foundation
5 Expires: August 4, 2003 J. Hildebrand
10 Nodeprep: A Stringprep Profile for Node Identifiers in XMPP
11 draft-ietf-xmpp-nodeprep-00
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
20 other groups may also distribute working documents as Internet-
23 Internet-Drafts are draft documents valid for a maximum of six months
24 and may be updated, replaced, or obsoleted by other documents at any
25 time. It is inappropriate to use Internet-Drafts as reference
26 material or to cite them other than as "work in progress."
28 The list of current Internet-Drafts can be accessed at http://
29 www.ietf.org/ietf/1id-abstracts.txt.
31 The list of Internet-Draft Shadow Directories can be accessed at
32 http://www.ietf.org/shadow.html.
34 This Internet-Draft will expire on August 4, 2003.
38 Copyright (C) The Internet Society (2003). All Rights Reserved.
42 This document defines a stringprep profile for node identifiers in
43 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 References . . . . . . . . . . . . . . . . . . . . . . . . . . 12
74 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 12
75 Full Copyright Statement . . . . . . . . . . . . . . . . . . . 13
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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 for XMPP node
123 identifiers only, and not for arbitrary text.
125 This profile defines the following, as required by RFC 3454 [1]:
127 o The intended applicability of the profile: internationalized node
128 identifiers within XMPP
130 o The character repertoire that is the input and output to
131 stringprep: Unicode 3.2, specified in section 2
133 o The mappings used: specified in section 3
135 o The Unicode normalization used: specified in section 4
137 o The characters that are prohibited as output: specified in section
140 o Bidirectional character handling: specified in section 6
145 This document inherits the terminology defined in XMPP Core [2].
147 The capitalized key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
148 "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
149 "OPTIONAL" in this document are to be interpreted as described in RFC
154 The authors welcome discussion and comments related to the topics
155 presented in this document. The preferred forum is the
156 <xmppwg@jabber.org> mailing list, for which archives and subscription
157 information are available at <http://www.jabber.org/cgi-bin/mailman/
160 1.3 Intellectual Property Notice
162 This document is in full compliance with all provisions of Section 10
163 of RFC 2026. Parts of this specification use the term "jabber" for
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172 identifying namespaces and other protocol syntax. Jabber[tm] is a
173 registered trademark of Jabber, Inc. Jabber, Inc. grants permission
174 to the IETF for use of the Jabber trademark in association with this
175 specification and its successors, if any.
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228 2. Character Repertoire
230 This profile uses Unicode 3.2, as defined in Appendix A.1 of RFC 3454
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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 Node identifiers are commonly employed as the username of users who
519 connect to XMPP servers for instant messaging and presence services.
520 The security of such services could be compromised if a user entering
521 a single internationalized node identifier could access another
522 user's account information based on different interpretations of the
523 internationalized node identifier.
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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 (draft-ietf-xmpp-core-
626 02, work in progress)", February 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 Full Copyright Statement
678 Copyright (C) The Internet Society (2003). All Rights Reserved.
680 This document and translations of it may be copied and furnished to
681 others, and derivative works that comment on or otherwise explain it
682 or assist in its implementation may be prepared, copied, published
683 and distributed, in whole or in part, without restriction of any
684 kind, provided that the above copyright notice and this paragraph are
685 included on all such copies and derivative works. However, this
686 document itself may not be modified in any way, such as by removing
687 the copyright notice or references to the Internet Society or other
688 Internet organizations, except as needed for the purpose of
689 developing Internet standards in which case the procedures for
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691 followed, or as required to translate it into languages other than
694 The limited permissions granted above are perpetual and will not be
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697 This document and the information contained herein is provided on an
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702 MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
706 Funding for the RFC Editor function is currently provided by the
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