draft-ietf-xmpp-address-05.txt   draft-ietf-xmpp-address-06.txt 
Network Working Group P. Saint-Andre Network Working Group P. Saint-Andre
Internet-Draft Cisco Internet-Draft Cisco
Intended status: Standards Track October 6, 2010 Intended status: Standards Track October 20, 2010
Expires: April 9, 2011 Expires: April 23, 2011
Extensible Messaging and Presence Protocol (XMPP): Address Format Extensible Messaging and Presence Protocol (XMPP): Address Format
draft-ietf-xmpp-address-05 draft-ietf-xmpp-address-06
Abstract Abstract
This document defines the format for addresses used in the Extensible This document defines the format for addresses used in the Extensible
Messaging and Presence Protocol (XMPP), including support for non- Messaging and Presence Protocol (XMPP), including support for non-
ASCII characters. ASCII characters.
Status of this Memo Status of this Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
skipping to change at page 1, line 32 skipping to change at page 1, line 32
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
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working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on April 9, 2011. This Internet-Draft will expire on April 23, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
2.1. Fundamentals . . . . . . . . . . . . . . . . . . . . . . . 4 3. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4
2.2. Domainpart . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Addresses . . . . . . . . . . . . . . . . . . . . . . . . . . 4
2.3. Localpart . . . . . . . . . . . . . . . . . . . . . . . . 6 4.1. Fundamentals . . . . . . . . . . . . . . . . . . . . . . . 4
2.4. Resourcepart . . . . . . . . . . . . . . . . . . . . . . . 7 4.2. Domainpart . . . . . . . . . . . . . . . . . . . . . . . . 5
3. Internationalization Considerations . . . . . . . . . . . . . 8 4.3. Localpart . . . . . . . . . . . . . . . . . . . . . . . . 7
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 4.4. Resourcepart . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Reuse of Stringprep . . . . . . . . . . . . . . . . . . . 8 5. Internationalization Considerations . . . . . . . . . . . . . 8
4.2. Reuse of Unicode . . . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . 8
4.3. Confusable Characters . . . . . . . . . . . . . . . . . . 8 6.1. Reuse of Stringprep . . . . . . . . . . . . . . . . . . . 8
4.4. Address Spoofing . . . . . . . . . . . . . . . . . . . . . 9 6.2. Reuse of Unicode . . . . . . . . . . . . . . . . . . . . . 9
4.4.1. Address Forging . . . . . . . . . . . . . . . . . . . 9 6.3. Address Spoofing . . . . . . . . . . . . . . . . . . . . . 9
4.4.2. Address Mimicking . . . . . . . . . . . . . . . . . . 10 6.3.1. Address Forging . . . . . . . . . . . . . . . . . . . 9
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 6.3.2. Address Mimicking . . . . . . . . . . . . . . . . . . 9
5.1. Nodeprep Profile of Stringprep . . . . . . . . . . . . . . 11 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
5.2. Resourceprep Profile of Stringprep . . . . . . . . . . . . 11 7.1. Nodeprep Profile of Stringprep . . . . . . . . . . . . . . 12
6. Conformance Requirements . . . . . . . . . . . . . . . . . . . 12 7.2. Resourceprep Profile of Stringprep . . . . . . . . . . . . 12
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8. Conformance Requirements . . . . . . . . . . . . . . . . . . . 13
7.1. Normative References . . . . . . . . . . . . . . . . . . . 13 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
7.2. Informative References . . . . . . . . . . . . . . . . . . 14 9.1. Normative References . . . . . . . . . . . . . . . . . . . 14
Appendix A. Nodeprep . . . . . . . . . . . . . . . . . . . . . . 16 9.2. Informative References . . . . . . . . . . . . . . . . . . 15
A.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 16 Appendix A. Nodeprep . . . . . . . . . . . . . . . . . . . . . . 17
A.2. Character Repertoire . . . . . . . . . . . . . . . . . . . 16 A.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 17
A.3. Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 17 A.2. Character Repertoire . . . . . . . . . . . . . . . . . . . 18
A.4. Normalization . . . . . . . . . . . . . . . . . . . . . . 17 A.3. Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 18
A.5. Prohibited Output . . . . . . . . . . . . . . . . . . . . 17 A.4. Normalization . . . . . . . . . . . . . . . . . . . . . . 18
A.6. Bidirectional Characters . . . . . . . . . . . . . . . . . 17 A.5. Prohibited Output . . . . . . . . . . . . . . . . . . . . 18
A.7. Notes . . . . . . . . . . . . . . . . . . . . . . . . . . 18 A.6. Bidirectional Characters . . . . . . . . . . . . . . . . . 19
Appendix B. Resourceprep . . . . . . . . . . . . . . . . . . . . 18 A.7. Notes . . . . . . . . . . . . . . . . . . . . . . . . . . 19
B.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 18 Appendix B. Resourceprep . . . . . . . . . . . . . . . . . . . . 19
B.2. Character Repertoire . . . . . . . . . . . . . . . . . . . 19 B.1. Introduction . . . . . . . . . . . . . . . . . . . . . . . 19
B.3. Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 19 B.2. Character Repertoire . . . . . . . . . . . . . . . . . . . 20
B.4. Normalization . . . . . . . . . . . . . . . . . . . . . . 19 B.3. Mapping . . . . . . . . . . . . . . . . . . . . . . . . . 20
B.5. Prohibited Output . . . . . . . . . . . . . . . . . . . . 19 B.4. Normalization . . . . . . . . . . . . . . . . . . . . . . 20
B.6. Bidirectional Characters . . . . . . . . . . . . . . . . . 19 B.5. Prohibited Output . . . . . . . . . . . . . . . . . . . . 20
Appendix C. Differences From RFC 3920 . . . . . . . . . . . . . . 20 B.6. Bidirectional Characters . . . . . . . . . . . . . . . . . 21
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 20 Appendix C. Differences From RFC 3920 . . . . . . . . . . . . . . 21
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 21
1. Introduction 1. Introduction
The Extensible Messaging and Presence Protocol (XMPP) is an The Extensible Messaging and Presence Protocol (XMPP) is an
application profile of the Extensible Markup Language [XML] for application profile of the Extensible Markup Language [XML] for
streaming XML data in close to real time between any two or more streaming XML data in close to real time between any two or more
network-aware entities. The address format for XMPP entities was network-aware entities. The address format for XMPP entities was
originally developed in the Jabber open-source community in 1999, originally developed in the Jabber open-source community in 1999,
first described by [XEP-0029] in 2002, and defined canonically by first described by [XEP-0029] in 2002, and defined canonically by
[RFC3920] in 2004. [RFC3920] in 2004.
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on stringprep. Following the lead of the IDNA community, other on stringprep. Following the lead of the IDNA community, other
technology communities that use stringprep have begun discussions technology communities that use stringprep have begun discussions
about migrating away from stringprep toward more "modern" approaches. about migrating away from stringprep toward more "modern" approaches.
The XMPP community is participating in those discussions in order to The XMPP community is participating in those discussions in order to
find a replacement for the Nodeprep and Resourceprep profiles of find a replacement for the Nodeprep and Resourceprep profiles of
stringprep defined in RFC 3920. However, work on improved handling stringprep defined in RFC 3920. However, work on improved handling
of internationalized addresses is currently in progress within the of internationalized addresses is currently in progress within the
PRECIS Working Group and at the time of this writing it seems that PRECIS Working Group and at the time of this writing it seems that
such work might take several years to complete. Because all other such work might take several years to complete. Because all other
aspects of revised documentation for XMPP have been incorporated into aspects of revised documentation for XMPP have been incorporated into
[rfc3920bis], the XMPP Working Group decided to split the XMPP [XMPP], the XMPP Working Group decided to split the XMPP address
address format into a separate specification so as not to format into a separate specification so as not to significantly delay
significantly delay publication of improved documentation for XMPP publication of improved documentation for XMPP while awaiting the
while awaiting the conclusion of work on improved handling of conclusion of work on improved handling of internationalized
internationalized addresses. addresses.
Therefore, this specification provides corrected documentation of the Therefore, this specification provides corrected documentation of the
XMPP address format using the internationalization technologies XMPP address format using the internationalization technologies
available in 2004 (when RFC 3920 was published), with the intent that available in 2004 (when RFC 3920 was published), with the intent that
this specification will be superseded as soon as work on a new this specification will be superseded as soon as work on a new
approach to preparation and comparison of internationalized strings approach to preparation and comparison of internationalized strings
has been defined by the PRECIS Working Group and applied to the has been defined by the PRECIS Working Group and applied to the
specific cases of XMPP localparts and resourceparts. specific cases of XMPP localparts and resourceparts.
2. Addresses 2. Terminology
2.1. Fundamentals
Many important terms used in this document are defined in [IDNA2003],
[STRINGPREP], [UNICODE], and [XMPP].
The keywords "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
[KEYWORDS].
3. Acknowledgements
Some text in this document was borrowed or adapted from [IDNA-DEFS],
[IDNA-PROTO], [IDNA-RATIONALE], and [XEP-0165].
4. Addresses
4.1. Fundamentals
An XMPP entity is anything that is network-addressable and that can An XMPP entity is anything that is network-addressable and that can
communicate using XMPP. For historical reasons, the native address communicate using XMPP. For historical reasons, the native address
of an XMPP entity is called a Jabber Identifier or JID. A valid JID of an XMPP entity is called a Jabber Identifier or JID. A valid JID
is a string of [UNICODE] code points, encoded using [UTF-8], and is a string of [UNICODE] code points, encoded using [UTF-8], and
structured as an ordered sequence of localpart, domainpart, and structured as an ordered sequence of localpart, domainpart, and
resourcepart (where the first two parts are demarcated by the '@' resourcepart (where the first two parts are demarcated by the '@'
character used as a separator, and the last two parts are similarly character used as a separator, and the last two parts are similarly
demarcated by the '/' character). demarcated by the '/' character).
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; code point that satisfies the Nameprep ; code point that satisfies the Nameprep
; profile of stringprep ; profile of stringprep
resourcepart = 1*(resourcepoint) resourcepart = 1*(resourcepoint)
; a "resourcepoint" is a UTF-8 encoded Unicode ; a "resourcepoint" is a UTF-8 encoded Unicode
; code point that satisfies the Resourceprep ; code point that satisfies the Resourceprep
; profile of stringprep ; profile of stringprep
All JIDs are based on the foregoing structure. One common use of All JIDs are based on the foregoing structure. One common use of
this structure is to identify a messaging and presence account, the this structure is to identify a messaging and presence account, the
server that hosts the account, and a connected resource (e.g., a server that hosts the account, and a connected resource (e.g., a
specific device) in the form of <localpart@domain/resource>. specific device) in the form of <localpart@domainpart/resourcepart>.
However, localparts other than clients are possible; for example, a However, localparts other than clients are possible; for example, a
specific chat room offered by a multi-user chat service (see specific chat room offered by a multi-user chat service (see
[XEP-0045]) is addressed as <room@service> (where "room" is the name [XEP-0045]) is addressed as <room@service> (where "room" is the name
of the chat room and "service" is the hostname of the multi-user chat of the chat room and "service" is the hostname of the multi-user chat
service) and a specific occupant of such a room could be addressed as service) and a specific occupant of such a room could be addressed as
<room@service/nick> (where "nick" is the occupant's room nickname). <room@service/nick> (where "nick" is the occupant's room nickname).
Many other JID types are possible (e.g., <domain/resource> could be a Many other JID types are possible (e.g., <domainpart/resourcepart>
server-side script or service). could be a server-side script or service).
Each allowable portion of a JID (localpart, domainpart, and Each allowable portion of a JID (localpart, domainpart, and
resourcepart) MUST NOT be zero bytes in length and MUST NOT be more resourcepart) MUST NOT be zero bytes in length and MUST NOT be more
than 1023 bytes in length, resulting in a maximum total size than 1023 bytes in length, resulting in a maximum total size
(including the '@' and '/' separators) of 3071 bytes. (including the '@' and '/' separators) of 3071 bytes.
An entity's address on an XMPP network MUST be represented as a JID An entity's address on an XMPP network MUST be represented as a JID
(without a URI scheme) and not a [URI] or [IRI] as specified in (without a URI scheme) and not a [URI] or [IRI] as specified in
[XMPP-URI]; the latter specification is provided only for [XMPP-URI]; the latter specification is provided only for
identification and interaction outside the context of XMPP itself. identification and interaction outside the context of XMPP itself.
Implementation Note: When dividing a JID into its component parts, Implementation Note: When dividing a JID into its component parts,
an implementation needs to match the separator characters '@' and an implementation needs to match the separator characters '@' and
'/' before applying any transformation algorithms, which might '/' before applying any transformation algorithms, which might
decompose certain Unicode code points to the separator characters decompose certain Unicode code points to the separator characters
(e.g., U+FE6B SMALL COMMERCIAL AT might decompose into U+0040 (e.g., U+FE6B SMALL COMMERCIAL AT might decompose into U+0040
COMMERCIAL AT). COMMERCIAL AT).
2.2. Domainpart 4.2. Domainpart
The DOMAINPART of a JID is that portion after the '@' character (if The DOMAINPART of a JID is that portion after the '@' character (if
any) and before the '/' character (if any); it is the primary any) and before the '/' character (if any); it is the primary
identifier and is the only REQUIRED element of a JID (a mere identifier and is the only REQUIRED element of a JID (a mere
domainpart is a valid JID). Typically a domainpart identifies the domainpart is a valid JID). Typically a domainpart identifies the
"home" server to which clients connect for XML routing and data "home" server to which clients connect for XML routing and data
management functionality. However, it is not necessary for an XMPP management functionality. However, it is not necessary for an XMPP
domainpart to identify an entity that provides core XMPP server domainpart to identify an entity that provides core XMPP server
functionality (e.g., a domainpart can identify an entity such as a functionality (e.g., a domainpart can identify an entity such as a
multi-user chat service, a publish-subscribe service, or a user multi-user chat service, a publish-subscribe service, or a user
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a network SHOULD be a fully qualified domain name or "FQDN" (see a network SHOULD be a fully qualified domain name or "FQDN" (see
[DNS]); although the domainpart is allowed to be either an Internet [DNS]); although the domainpart is allowed to be either an Internet
Protocol (IPv4 or IPv6) address or a text label that is resolvable on Protocol (IPv4 or IPv6) address or a text label that is resolvable on
a local network (commonly called an "unqualified hostname"), it is a local network (commonly called an "unqualified hostname"), it is
possible that domainparts that are IP addresses will not be possible that domainparts that are IP addresses will not be
acceptable to other services for the sake of interdomain acceptable to other services for the sake of interdomain
communication. Furthermore, domainparts that are unqualified communication. Furthermore, domainparts that are unqualified
hostnames MUST NOT be used on public networks but MAY be used on hostnames MUST NOT be used on public networks but MAY be used on
private networks. private networks.
Note: If the domainpart includes a final character considered to Implementation Note: If the domainpart includes a final character
be a label separator (dot) by [IDNA2003] or [DNS], this character considered to be a label separator (dot) by [IDNA2003] or [DNS],
MUST be stripped from the domainpart before the JID of which it is this character MUST be stripped from the domainpart before the JID
a part is used for the purpose of routing an XML stanza, comparing of which it is a part is used for the purpose of routing an XML
against another JID, or constructing an [XMPP-URI]; in particular, stanza, comparing against another JID, or constructing an
the character MUST be stripped before any other canonicalization [XMPP-URI]; in particular, the character MUST be stripped before
steps are taken, such as application of the [NAMEPREP] profile of any other canonicalization steps are taken, such as application of
[STRINGPREP] or completion of the ToASCII operation as described the [NAMEPREP] profile of [STRINGPREP] or completion of the
in [IDNA2003]. ToASCII operation as described in [IDNA2003].
A domainpart MUST NOT be zero bytes in length and MUST NOT be more A domainpart MUST NOT be zero bytes in length and MUST NOT be more
than 1023 bytes in length. than 1023 bytes in length.
A domainpart consisting of a fully qualified domain name MUST be an A domainpart consisting of a fully qualified domain name MUST be an
"internationalized domain name" as defined in [IDNA2003], that is, it "internationalized domain name" as defined in [IDNA2003], that is, it
MUST be "a domain name in which every label is an internationalized MUST be "a domain name in which every label is an internationalized
label" and MUST follow the rules for construction of label" and MUST follow the rules for construction of
internationalized domain names specified in [IDNA2003]. When internationalized domain names specified in [IDNA2003]. When
preparing a text label (consisting of a sequence of UTF-8 encoded preparing a text label (consisting of a sequence of UTF-8 encoded
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that ACE label to an internationalized label using the ToUnicode that ACE label to an internationalized label using the ToUnicode
operation (see [IDNA2003]) before including the label in an XMPP operation (see [IDNA2003]) before including the label in an XMPP
domainpart that will be communicated over the wire on an XMPP network domainpart that will be communicated over the wire on an XMPP network
(however, instead of converting the label, there are legitimate (however, instead of converting the label, there are legitimate
reasons why an application might instead refuse the input altogether reasons why an application might instead refuse the input altogether
and return an error to the entity that provided the offending data). and return an error to the entity that provided the offending data).
In the terms of IDNA2008 [IDNA-DEFS], the domainpart of a JID is a In the terms of IDNA2008 [IDNA-DEFS], the domainpart of a JID is a
"domain name slot". "domain name slot".
2.3. Localpart 4.3. Localpart
The LOCALPART of a JID is an optional identifier placed before the The LOCALPART of a JID is an optional identifier placed before the
domainpart and separated from the latter by the '@' character. domainpart and separated from the latter by the '@' character.
Typically a localpart uniquely identifies the entity requesting and Typically a localpart uniquely identifies the entity requesting and
using network access provided by a server (i.e., a local account), using network access provided by a server (i.e., a local account),
although it can also represent other kinds of entities (e.g., a chat although it can also represent other kinds of entities (e.g., a chat
room associated with a multi-user chat service). The entity room associated with a multi-user chat service). The entity
represented by an XMPP localpart is addressed within the context of a represented by an XMPP localpart is addressed within the context of a
specific domain. specific domain.
A localpart MUST NOT be zero bytes in length and MUST NOT be more A localpart MUST NOT be zero bytes in length and MUST NOT be more
than 1023 bytes in length. than 1023 bytes in length.
A localpart MUST be formatted such that the Nodeprep profile of A localpart MUST be formatted such that the Nodeprep profile of
[STRINGPREP] can be applied without failing (see Appendix A). Before [STRINGPREP] can be applied without failing (see Appendix A). Before
comparing two localparts, an application MUST first ensure that the comparing two localparts, an application MUST first ensure that the
Nodeprep profile has been applied to each identifier (the profile Nodeprep profile has been applied to each identifier (the profile
need not be applied each time a comparison is made, as long as it has need not be applied each time a comparison is made, as long as it has
been applied before comparison). been applied before comparison).
2.4. Resourcepart 4.4. Resourcepart
The resourcepart of a JID is an optional identifier placed after the The resourcepart of a JID is an optional identifier placed after the
domainpart and separated from the latter by the '/' character. A domainpart and separated from the latter by the '/' character. A
resourcepart can modify either a <localpart@domainpart> address or a resourcepart can modify either a <localpart@domainpart> address or a
mere <domainpart> address. Typically a resourcepart uniquely mere <domainpart> address. Typically a resourcepart uniquely
identifies a specific connection (e.g., a device or location) or identifies a specific connection (e.g., a device or location) or
object (e.g., an occupant in a multi-user chat room) belonging to the object (e.g., an occupant in a multi-user chat room) belonging to the
entity associated with an XMPP localpart at a local domain. entity associated with an XMPP localpart at a local domain.
When an XMPP address does not include a resourcepart (i.e., when it When an XMPP address does not include a resourcepart (i.e., when it
is of the form <domainpart> or <localpart@domainpart>), it is is of the form <domainpart> or <localpart@domainpart>), it is
referred to as a BARE JID. When an XMPP address includes a referred to as a BARE JID. When an XMPP address includes a
resourcepart (i.e., when it is of the form <domain/resource> or resourcepart (i.e., when it is of the form <domainpart/resourcepart>
<localpart@domain/resource>), is referred to as a FULL JID. or <localpart@domainpart/resourcepart>), is referred to as a FULL
JID.
A resourcepart MUST NOT be zero bytes in length and MUST NOT be more A resourcepart MUST NOT be zero bytes in length and MUST NOT be more
than 1023 bytes in length. than 1023 bytes in length.
A resourcepart MUST be formatted such that the Resourceprep profile A resourcepart MUST be formatted such that the Resourceprep profile
of [STRINGPREP] can be applied without failing (see Appendix B). of [STRINGPREP] can be applied without failing (see Appendix B).
Before comparing two resourceparts, an application MUST first ensure Before comparing two resourceparts, an application MUST first ensure
that the Resourceprep profile has been applied to each identifier that the Resourceprep profile has been applied to each identifier
(the profile need not be applied each time a comparison is made, as (the profile need not be applied each time a comparison is made, as
long as it has been applied before comparison). long as it has been applied before comparison).
Note: For historical reasons, the term "resource identifier" is Informational Note: For historical reasons, the term "resource
often used in XMPP to refer to the optional portion of an XMPP identifier" is often used in XMPP to refer to the optional portion
address that follows the domainpart and the "/" separator of an XMPP address that follows the domainpart and the "/"
character; to help prevent confusion between an XMPP "resource separator character; to help prevent confusion between an XMPP
identifier" and the meanings of "resource" and "identifier" "resource identifier" and the meanings of "resource" and
provided in Section 1.1 of [URI], this specification uses the term "identifier" provided in Section 1.1 of [URI], this specification
"resourcepart" instead of "resource identifier" (as in RFC 3920). uses the term "resourcepart" instead of "resource identifier" (as
in RFC 3920).
XMPP entities SHOULD consider resourceparts to be opaque strings and XMPP entities SHOULD consider resourceparts to be opaque strings and
SHOULD NOT impute meaning to any given resourcepart. In particular: SHOULD NOT impute meaning to any given resourcepart. In particular:
o Use of the '/' character as a separator between the domainpart and o Use of the '/' character as a separator between the domainpart and
the resourcepart does not imply that XMPP addresses are the resourcepart does not imply that XMPP addresses are
hierarchical in the way that, say, HTTP addresses are hierarchical in the way that, say, HTTP addresses are
hierarchical; thus for example an XMPP address of the form hierarchical; thus for example an XMPP address of the form
<localpart@domain/foo/bar> does not identify a resource "bar" that <localpart@domainpart/foo/bar> does not identify a resource "bar"
exists below a resource "foo" in a hierarchy of resources that exists below a resource "foo" in a hierarchy of resources
associated with the entity "localpart@domain". associated with the entity "localpart@domain".
o The '@' character is allowed in the resourcepart, and is often o The '@' character is allowed in the resourcepart, and is often
used in the "nick" shown in XMPP chatrooms. For example, the JID used in the "nick" shown in XMPP chatrooms. For example, the JID
<room@chat.example.com/user@host> describes an entity who is an <room@chat.example.com/user@host> describes an entity who is an
occupant of the room <room@chat.example.com> with an (asserted) occupant of the room <room@chat.example.com> with an (asserted)
nick of <user@host>. However, chatroom services do not nick of <user@host>. However, chatroom services do not
necessarily check such an asserted nick against the occupant's necessarily check such an asserted nick against the occupant's
real JID. real JID.
3. Internationalization Considerations 5. Internationalization Considerations
XMPP servers MUST, and XMPP clients SHOULD, support [IDNA2003] for XMPP servers MUST, and XMPP clients SHOULD, support [IDNA2003] for
domainparts (including the [NAMEPREP] profile of [STRINGPREP]), the domainparts (including the [NAMEPREP] profile of [STRINGPREP]), the
Nodeprep (Appendix A) profile of [STRINGPREP] for localparts, and the Nodeprep (Appendix A) profile of [STRINGPREP] for localparts, and the
Resourceprep (Appendix B) profile of [STRINGPREP] for resourceparts; Resourceprep (Appendix B) profile of [STRINGPREP] for resourceparts;
this enables XMPP addresses to include a wide variety of characters this enables XMPP addresses to include a wide variety of characters
outside the US-ASCII range. Rules for enforcement of the XMPP outside the US-ASCII range. Rules for enforcement of the XMPP
address format are provided in [rfc3920bis]. address format are provided in [XMPP].
4. Security Considerations 6. Security Considerations
4.1. Reuse of Stringprep 6.1. Reuse of Stringprep
The security considerations described in [STRINGPREP] apply to the The security considerations described in [STRINGPREP] apply to the
Nodeprep (Appendix A) and Resourceprep (Appendix B) profiles defined Nodeprep (Appendix A) and Resourceprep (Appendix B) profiles defined
in this document for XMPP localparts and resourceparts. The security in this document for XMPP localparts and resourceparts. The security
considerations described in [STRINGPREP] and [NAMEPREP] apply to the considerations described in [STRINGPREP] and [NAMEPREP] apply to the
Nameprep profile that is re-used here for XMPP domainparts. Nameprep profile that is re-used here for XMPP domainparts.
4.2. Reuse of Unicode 6.2. Reuse of Unicode
The security considerations described in [UNICODE-SEC] apply to the The security considerations described in [UNICODE-SEC] apply to the
use of Unicode characters in XMPP addresses. use of Unicode characters in XMPP addresses.
4.3. Confusable Characters 6.3. Address Spoofing
The Unicode and ISO/IEC 10646 repertoires have many characters that
look similar (so-called "confusable characters"). In many cases,
users of security protocols might perform visual matching, such as
when comparing the names of trusted third parties. Because it is
impossible to map similar-looking characters without a great deal of
context (such as knowing the fonts used), stringprep does nothing to
map similar-looking characters together, nor to prohibit some
characters because they look like others. Some specific suggestions
about identification and handling of confusable characters appear in
the Unicode Security Considerations [UNICODE-SEC].
A localpart can be employed as one part of an entity's address in
XMPP. One common usage is as the username of an instant messaging
user; another is as the name of a multi-user chat room; and many
other kinds of entities could use localparts as part of their
addresses. The security of such services could be compromised based
on different interpretations of the internationalized localpart; for
example, a user entering a single internationalized localpart could
access another user's account information, or a user could gain
access to a hidden or otherwise restricted chat room or service.
A resourcepart can be employed as one part of an entity's address in
XMPP. One common usage is as the name for an instant messaging
user's connected resource; another is as the nickname of a user in a
multi-user chat room; and many other kinds of entities could use
resourceparts as part of their addresses. The security of such
services could be compromised based on different interpretations of
the internationalized resourcepart; for example, a user could attempt
to initiate multiple connections with the same name, or a user could
send a message to someone other than the intended recipient in a
multi-user chat room.
4.4. Address Spoofing
There are two forms of address spoofing: forging and mimicking. There are two forms of address spoofing: forging and mimicking.
4.4.1. Address Forging 6.3.1. Address Forging
In the context of XMPP technologies, address forging occurs when an In the context of XMPP technologies, address forging occurs when an
entity is able to generate an XML stanza whose 'from' address does entity is able to generate an XML stanza whose 'from' address does
not correspond to the account credentials with which the entity not correspond to the account credentials with which the entity
authenticated onto the network (or an authorization identity provided authenticated onto the network (or an authorization identity provided
during SASL negotiation). For example, address forging occurs if an during SASL negotiation). For example, address forging occurs if an
entity that authenticated as "juliet@im.example.com" is able to send entity that authenticated as "juliet@im.example.com" is able to send
XML stanzas from "nurse@im.example.com" or "romeo@example.net". XML stanzas from "nurse@im.example.com" or "romeo@example.net".
Address forging is difficult in XMPP systems, given the requirement Address forging is difficult in XMPP systems, given the requirement
for sending servers to stamp 'from' addresses and for receiving for sending servers to stamp 'from' addresses and for receiving
servers to verify sending domains via server-to-server authentication servers to verify sending domains via server-to-server authentication
(see [rfc3920bis]). However, address forging is not impossible, (see [XMPP]). However, address forging is not impossible, since a
since a rogue server could forge JIDs at the sending domain by rogue server could forge JIDs at the sending domain by ignoring the
ignoring the stamping requirement. Therefore, an entity outside the stamping requirement. Therefore, an entity outside the security
security perimeter of a particular server cannot reliably distinguish perimeter of a particular server cannot reliably distinguish between
between bare JIDs of the form <localpart@domainpart> at that server bare JIDs of the form <localpart@domainpart> at that server and thus
and thus can authenticate only the domainpart of such JIDs with any can authenticate only the domainpart of such JIDs with any level of
level of assurance. This specification does not define methods for assurance. This specification does not define methods for
discovering or counteracting such rogue servers. discovering or counteracting such rogue servers.
Furthermore, it is possible for an attacker to forge JIDs at other Furthermore, it is possible for an attacker to forge JIDs at other
domains by means of a DNS poisoning attack if DNS security extensions domains by means of a DNS poisoning attack if DNS security extensions
[DNSSEC] are not used. [DNSSEC] are not used.
4.4.2. Address Mimicking 6.3.2. Address Mimicking
Address mimicking occurs when an entity provides legitimate Address mimicking occurs when an entity provides legitimate
authentication credentials for and sends XML stanzas from an account authentication credentials for and sends XML stanzas from an account
whose JID appears to a human user to be the same as another JID. For whose JID appears to a human user to be the same as another JID. For
example, in some XMPP clients the address "paypa1@example.org" example, in some XMPP clients the address "ju1iet@example.org"
(spelled with the number one as the final character of the localpart) (spelled with the number one as the third character of the localpart)
might appear to be the same as "paypal@example.org (spelled with the might appear to be the same as "juliet@example.org (spelled with the
lower-case version of the letter "L"), especially on casual visual lower-case version of the letter "L"), especially on casual visual
inspection; this phenomenon is sometimes called "typejacking". A inspection; this phenomenon is sometimes called "typejacking". A
more sophisticated example of address mimicking might involve the use more sophisticated example of address mimicking might involve the use
of characters from outside the US-ASCII range, such as the Cherokee of characters from outside the familiar Latin extended-A block of
characters U+13DA U+13A2 U+13B5 U+13AC U+13A2 U+13AC U+13D2 instead Unicode code points, such as the characters U+13DA U+13A2 U+13B5
of the US-ASCII characters "STPETER". U+13AC U+13A2 U+13AC U+13D2 from the Cherokee block instead of the
similar-looking US-ASCII characters "STPETER".
In some examples of address mimicking, it is unlikely that the In some examples of address mimicking, it is unlikely that the
average user could tell the difference between the real JID and the average user could tell the difference between the real JID and the
fake JID. (Indeed, there is no way to distinguish with full fake JID. (Indeed, there is no programmatic way to distinguish with
certainty which is the fake JID and which is the real JID; in some full certainty which is the fake JID and which is the real JID; in
communication contexts, the JID with Cherokee characters might be the some communication contexts, the JID formed of Cherokee characters
real JID and the JID with US-ASCII characters might thus appear to be might be the real JID and the JID formed of US-ASCII characters might
the fake JID.) Because JIDs can contain almost any Unicode thus appear to be the fake JID.) Because JIDs can contain almost any
character, it can be relatively easy to mimic some JIDs in XMPP properly-encoded Unicode code point, it can be relatively easy to
systems. The possibility of address mimicking introduces security mimic some JIDs in XMPP systems. The possibility of address
vulnerabilities of the kind that have also plagued the World Wide mimicking introduces security vulnerabilities of the kind that have
Web, specifically the phenomenon known as phishing. also plagued the World Wide Web, specifically the phenomenon known as
phishing.
As noted in [IDNA-DEFS], "there are no comprehensive technical These problems arise because Unicode and ISO/IEC 10646 repertoires
solutions to the problems of confusable characters". Mimicked JIDs have many characters that look similar (so-called "confusable
that involve characters from only one character set or from the characters" or "confusables"). In many cases, XMPP users might
character set typically employed by a particular user are not easy to perform visual matching, such as when comparing the JIDs of
combat (e.g., the simple typejacking attack previously described, communication partners. Because it is impossible to map similar-
which relies on a surface similarity between the characters "1" and looking characters without a great deal of context (such as knowing
"l" in some presentations). However, mimicked addresses that involve the fonts used), stringprep and stringprep-based technologies such as
characters from more than one character set, or from a character set Nameprep, Nodeprep, and Resourceprep do nothing to map similar-
not typically employed by a particular user, can be mitigated looking characters together, nor do they prohibit some characters
somewhat through intelligent presentation. In particular, every because they look like others. As a result, XMPP localparts and
human user of an XMPP technology presumably has a preferred language resourceparts could contain confusable characters, producing JIDs
(or, in some cases, a small set of preferred languages), which an that appear to mimic other JIDs and thus leading to security
XMPP application SHOULD gather either explicitly from the user or vulnerabilities such as the following:
implicitly via the operating system of the user's device.
Furthermore, every language has a range (or a small set of ranges) of o A localpart can be employed as one part of an entity's address in
characters normally used to represent that language in textual form. XMPP. One common usage is as the username of an instant messaging
Therefore, an XMPP application SHOULD warn the user when presenting a user; another is as the name of a multi-user chat room; and many
JID that mixes characters from more than one character set or that other kinds of entities could use localparts as part of their
uses characters outside the normal range of the user's preferred addresses. The security of such services could be compromised
language(s). This recommendation is not intended to discourage based on different interpretations of the internationalized
communication across language communities; instead, it recognizes the localpart; for example, a user entering a single internationalized
existence of such language communities and encourages due caution localpart could access another user's account information, or a
when presenting unfamiliar character sets to human users. user could gain access to a hidden or otherwise restricted chat
room or service.
5. IANA Considerations o A resourcepart can be employed as one part of an entity's address
in XMPP. One common usage is as the name for an instant messaging
user's connected resource; another is as the nickname of a user in
a multi-user chat room; and many other kinds of entities could use
resourceparts as part of their addresses. The security of such
services could be compromised based on different interpretations
of the internationalized resourcepart; for example, a user could
attempt to bind multiple resources with the same name, or a user
could send a message to someone other than the intended recipient
in a multi-user chat room.
Despite the fact that some specific suggestions about identification
and handling of confusable characters appear in the Unicode Security
Considerations [UNICODE-SEC], it is also true (as noted in
[IDNA-DEFS]) that "there are no comprehensive technical solutions to
the problems of confusable characters". Mimicked JIDs that involve
characters from only one script, or from the script typically
employed by a particular user or community of language users, are not
easy to combat (e.g., the simple typejacking attack previously
described, which relies on a surface similarity between the
characters "1" and "l" in some presentations). However, mimicked
addresses that involve characters from more than one script, or from
a script not typically employed by a particular user or community of
language users, can be mitigated somewhat through the application of
appropriate registration policies at XMPP services and presentation
policies in XMPP client software. Therefore the following policies
are encouraged:
1. Because an XMPP service that allows registration of XMPP user
accounts (localparts) plays a role similar to that of a registry
for DNS domain names, such a service SHOULD establish a policy
about the scripts or blocks of characters it will allow in
localparts at the service. Such a policy is likely to be
informed by the languages and scripts that are used to write
registered account names; in particular, to reduce confusion, the
service MAY forbid registration of XMPP localparts that contain
characters from more than one script and to restrict
registrations to characters drawn from a very small number of
scripts (e.g., scripts that are well-understood by the
administrators of the service). For related considerations in
the context of domain name registration, refer to Section 4.3 of
[IDNA-PROTO] and Section 3.2 of [IDNA-RATIONALE]. Note well that
methods for enforcing such restrictions are out of scope for this
document.
2. Because every human user of an XMPP client presumably has a
preferred language (or, in some cases, a small set of preferred
languages), an XMPP client SHOULD gather that information either
explicitly from the user or implicitly via the operating system
of the user's device. Furthermore, because most languages are
typically represented by a single script (or a small set of
scripts) and most scripts are typically contained in one or more
blocks of characters, an XMPP client SHOULD warn the user when
presenting a JID that mixes characters from more than one script
or block, or that uses characters outside the normal range of the
user's preferred language(s). This recommendation is not
intended to discourage communication across different communities
of language users; instead, it recognizes the existence of such
communities and encourages due caution when presenting unfamiliar
scripts or characters to human users.
7. IANA Considerations
The following sections update the registrations provided in The following sections update the registrations provided in
[RFC3920]. [RFC3920].
5.1. Nodeprep Profile of Stringprep 7.1. Nodeprep Profile of Stringprep
The Nodeprep profile of stringprep is defined under Nodeprep The Nodeprep profile of stringprep is defined under Nodeprep
(Appendix A). The IANA has registered Nodeprep in the stringprep (Appendix A). The IANA has registered Nodeprep in the stringprep
profile registry. profile registry.
Name of this profile: Name of this profile:
Nodeprep Nodeprep
RFC in which the profile is defined: RFC in which the profile is defined:
XXXX XXXX
Indicator whether or not this is the newest version of the profile: Indicator whether or not this is the newest version of the profile:
This is the first version of Nodeprep This is the first version of Nodeprep
5.2. Resourceprep Profile of Stringprep 7.2. Resourceprep Profile of Stringprep
The Resourceprep profile of stringprep is defined under Resourceprep The Resourceprep profile of stringprep is defined under Resourceprep
(Appendix B). The IANA has registered Resourceprep in the stringprep (Appendix B). The IANA has registered Resourceprep in the stringprep
profile registry. profile registry.
Name of this profile: Name of this profile:
Resourceprep Resourceprep
RFC in which the profile is defined: RFC in which the profile is defined:
XXXX XXXX
Indicator whether or not this is the newest version of the profile: Indicator whether or not this is the newest version of the profile:
This is the first version of Resourceprep This is the first version of Resourceprep
6. Conformance Requirements 8. Conformance Requirements
This section describes a protocol feature set that summarizes the This section describes a protocol feature set that summarizes the
conformance requirements of this specification. This feature set is conformance requirements of this specification. This feature set is
appropriate for use in software certification, interoperability appropriate for use in software certification, interoperability
testing, and implementation reports. For each feature, this section testing, and implementation reports. For each feature, this section
provides the following information: provides the following information:
o A human-readable name o A human-readable name
o An informational description o An informational description
skipping to change at page 12, line 44 skipping to change at page 13, line 44
formats proposed by Larry Masinter within the IETF's NEWTRK Working formats proposed by Larry Masinter within the IETF's NEWTRK Working
Group in 2005, as captured in [INTEROP]. Although this feature set Group in 2005, as captured in [INTEROP]. Although this feature set
is more detailed than called for by [REPORTS], it provides a suitable is more detailed than called for by [REPORTS], it provides a suitable
basis for the generation of implementation reports to be submitted in basis for the generation of implementation reports to be submitted in
support of advancing this specification from Proposed Standard to support of advancing this specification from Proposed Standard to
Draft Standard in accordance with [PROCESS]. Draft Standard in accordance with [PROCESS].
Feature: address-domain-length Feature: address-domain-length
Description: Ensure that the domainpart of an XMPP address is at Description: Ensure that the domainpart of an XMPP address is at
least one byte in length and at most 1023 bytes in length. least one byte in length and at most 1023 bytes in length.
Section: Section 2.2 Section: Section 4.2
Roles: Both MUST. Roles: Both MUST.
Feature: address-domain-prep Feature: address-domain-prep
Description: Ensure that the domainpart of an XMPP address conforms Description: Ensure that the domainpart of an XMPP address conforms
to the Nameprep profile of Stringprep. to the Nameprep profile of Stringprep.
Section: Section 2.2 Section: Section 4.2
Roles: Client SHOULD, Server MUST. Roles: Client SHOULD, Server MUST.
Feature: address-localpart-length Feature: address-localpart-length
Description: Ensure that the localpart of an XMPP address is at Description: Ensure that the localpart of an XMPP address is at
least one byte in length and at most 1023 bytes in length. least one byte in length and at most 1023 bytes in length.
Section: Section 2.3 Section: Section 4.3
Roles: Both MUST. Roles: Both MUST.
Feature: address-localpart-prep Feature: address-localpart-prep
Description: Ensure that the localpart of an XMPP address conforms Description: Ensure that the localpart of an XMPP address conforms
to the Nodeprep profile of Stringprep. to the Nodeprep profile of Stringprep.
Section: Section 2.3 Section: Section 4.3
Roles: Client SHOULD, Server MUST. Roles: Client SHOULD, Server MUST.
Feature: address-resource-length Feature: address-resource-length
Description: Ensure that the resourcepart of an XMPP address is at Description: Ensure that the resourcepart of an XMPP address is at
least one byte in length and at most 1023 bytes in length. least one byte in length and at most 1023 bytes in length.
Section: Section 2.4 Section: Section 4.4
Roles: Both MUST. Roles: Both MUST.
Feature: address-resource-prep Feature: address-resource-prep
Description: Ensure that the resourcepart of an XMPP address Description: Ensure that the resourcepart of an XMPP address
conforms to the Resourceprep profile of Stringprep. conforms to the Resourceprep profile of Stringprep.
Section: Section 2.2 Section: Section 4.2
Roles: Client SHOULD, Server MUST. Roles: Client SHOULD, Server MUST.
7. References 9. References
7.1. Normative References 9.1. Normative References
[ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax [ABNF] Crocker, D. and P. Overell, "Augmented BNF for Syntax
Specifications: ABNF", STD 68, RFC 5234, January 2008. Specifications: ABNF", STD 68, RFC 5234, January 2008.
[IDNA2003] [IDNA2003]
Faltstrom, P., Hoffman, P., and A. Costello, Faltstrom, P., Hoffman, P., and A. Costello,
"Internationalizing Domain Names in Applications (IDNA)", "Internationalizing Domain Names in Applications (IDNA)",
RFC 3490, March 2003. RFC 3490, March 2003.
See Section 1 for an explanation of why the normative See Section 1 for an explanation of why the normative
skipping to change at page 14, line 13 skipping to change at page 15, line 13
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[NAMEPREP] [NAMEPREP]
Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep Hoffman, P. and M. Blanchet, "Nameprep: A Stringprep
Profile for Internationalized Domain Names (IDN)", Profile for Internationalized Domain Names (IDN)",
RFC 3491, March 2003. RFC 3491, March 2003.
See Section 1 for an explanation of why the normative See Section 1 for an explanation of why the normative
reference to an obsoleted specification is needed. reference to an obsoleted specification is needed.
[rfc3920bis]
Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", draft-ietf-xmpp-3920bis-17 (work
in progress), October 2010.
[STRINGPREP] [STRINGPREP]
Hoffman, P. and M. Blanchet, "Preparation of Hoffman, P. and M. Blanchet, "Preparation of
Internationalized Strings ("stringprep")", RFC 3454, Internationalized Strings ("stringprep")", RFC 3454,
December 2002. December 2002.
[UNICODE] The Unicode Consortium, "The Unicode Standard, Version [UNICODE] The Unicode Consortium, "The Unicode Standard, Version
3.2.0", 2000. 3.2.0", 2000.
The Unicode Standard, Version 3.2.0 is defined by The The Unicode Standard, Version 3.2.0 is defined by The
Unicode Standard, Version 3.0 (Reading, MA, Addison- Unicode Standard, Version 3.0 (Reading, MA, Addison-
skipping to change at page 14, line 41 skipping to change at page 15, line 36
Standard Annex #28: Unicode 3.2 Standard Annex #28: Unicode 3.2
(http://www.unicode.org/reports/tr28/). (http://www.unicode.org/reports/tr28/).
[UNICODE-SEC] [UNICODE-SEC]
The Unicode Consortium, "Unicode Technical Report #36: The Unicode Consortium, "Unicode Technical Report #36:
Unicode Security Considerations", 2008. Unicode Security Considerations", 2008.
[UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO [UTF-8] Yergeau, F., "UTF-8, a transformation format of ISO
10646", STD 63, RFC 3629, November 2003. 10646", STD 63, RFC 3629, November 2003.
7.2. Informative References [XMPP] Saint-Andre, P., "Extensible Messaging and Presence
Protocol (XMPP): Core", draft-ietf-xmpp-3920bis-17 (work
in progress), October 2010.
9.2. Informative References
[DNS] Mockapetris, P., "Domain names - implementation and [DNS] Mockapetris, P., "Domain names - implementation and
specification", STD 13, RFC 1035, November 1987. specification", STD 13, RFC 1035, November 1987.
[DNSSEC] Arends, R., Austein, R., Larson, M., Massey, D., and S. [DNSSEC] Arends, R., Austein, R., Larson, M., Massey, D., and S.
Rose, "DNS Security Introduction and Requirements", Rose, "DNS Security Introduction and Requirements",
RFC 4033, March 2005. RFC 4033, March 2005.
[IDNA-DEFS] [IDNA-DEFS]
Klensin, J., "Internationalized Domain Names for Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Definitions and Document Framework", Applications (IDNA): Definitions and Document Framework",
RFC 5890, August 2010. RFC 5890, August 2010.
[IDNA-PROTO] [IDNA-PROTO]
Klensin, J., "Internationalized Domain Names in Klensin, J., "Internationalized Domain Names in
Applications (IDNA): Protocol", RFC 5891, August 2010. Applications (IDNA): Protocol", RFC 5891, August 2010.
[IDNA-RATIONALE]
Klensin, J., "Internationalized Domain Names for
Applications (IDNA): Background, Explanation, and
Rationale", RFC 5894, August 2010.
[INTEROP] Masinter, L., "Formalizing IETF Interoperability [INTEROP] Masinter, L., "Formalizing IETF Interoperability
Reporting", draft-ietf-newtrk-interop-reports-00 (work in Reporting", draft-ietf-newtrk-interop-reports-00 (work in
progress), October 2005. progress), October 2005.
[IRI] Duerst, M. and M. Suignard, "Internationalized Resource [IRI] Duerst, M. and M. Suignard, "Internationalized Resource
Identifiers (IRIs)", RFC 3987, January 2005. Identifiers (IRIs)", RFC 3987, January 2005.
[PROCESS] Bradner, S., "The Internet Standards Process -- Revision [PROCESS] Bradner, S., "The Internet Standards Process -- Revision
3", BCP 9, RFC 2026, October 1996. 3", BCP 9, RFC 2026, October 1996.
skipping to change at page 15, line 46 skipping to change at page 16, line 50
[XEP-0029] [XEP-0029]
Kaes, C., "Definition of Jabber Identifiers (JIDs)", XSF Kaes, C., "Definition of Jabber Identifiers (JIDs)", XSF
XEP 0029, October 2003. XEP 0029, October 2003.
[XEP-0030] [XEP-0030]
Hildebrand, J., Millard, P., Eatmon, R., and P. Saint- Hildebrand, J., Millard, P., Eatmon, R., and P. Saint-
Andre, "Service Discovery", XSF XEP 0030, June 2008. Andre, "Service Discovery", XSF XEP 0030, June 2008.
[XEP-0045] [XEP-0045]
Saint-Andre, P., "Multi-User Chat", XSF XEP 0045, Saint-Andre, P., "Multi-User Chat", XSF XEP 0045,
January in progress, last updated 2010. July 2008.
[XEP-0060] [XEP-0060]
Millard, P., Saint-Andre, P., and R. Meijer, "Publish- Millard, P., Saint-Andre, P., and R. Meijer, "Publish-
Subscribe", XSF XEP 0060, September 2008. Subscribe", XSF XEP 0060, September 2008.
[XEP-0165]
Saint-Andre, P., "Best Practices to Discourage JID
Mimicking", XSF XEP 0045, December 2007.
[XML] Paoli, J., Maler, E., Sperberg-McQueen, C., Yergeau, F., [XML] Paoli, J., Maler, E., Sperberg-McQueen, C., Yergeau, F.,
and T. Bray, "Extensible Markup Language (XML) 1.0 (Fourth and T. Bray, "Extensible Markup Language (XML) 1.0 (Fourth
Edition)", World Wide Web Consortium Recommendation REC- Edition)", World Wide Web Consortium Recommendation REC-
xml-20060816, August 2006, xml-20060816, August 2006,
<http://www.w3.org/TR/2006/REC-xml-20060816>. <http://www.w3.org/TR/2006/REC-xml-20060816>.
[XMPP-URI] [XMPP-URI]
Saint-Andre, P., "Internationalized Resource Identifiers Saint-Andre, P., "Internationalized Resource Identifiers
(IRIs) and Uniform Resource Identifiers (URIs) for the (IRIs) and Uniform Resource Identifiers (URIs) for the
Extensible Messaging and Presence Protocol (XMPP)", Extensible Messaging and Presence Protocol (XMPP)",
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