On 2015-02-03 11:07, Winfried Tilanus wrote: > On 03-02-15 11:03, Ralph Meijer wrote: >> Sure it will be short. However, some notes on limitations and security >> considerations would also need to be added. If only to make it easier to >> compare against other e2e proposals. If you want to make a start with a >> XEP, that's appreciated. > > https://github.com/winfried/XMPP-OTR > > If you give me your github name, I will give you write access ;-)
I have an early draft I started on for "Current OTR Usage in XMPP" but I've been busy with other things. It has some of the issues we have with it written down, which needs to be word-smithed to something more formal. Might be useful as a starting point. -- Kim "Zash" AlvefurTitle: XEP-xxxx: Current OTR Usage in XMPP
XEP-xxxx: Current OTR Usage in XMPP
WARNING: This document has not yet been accepted for consideration or approved in any official manner by the XMPP Standards Foundation, and this document is not yet an XMPP Extension Protocol (XEP). If this document is accepted as a XEP by the XMPP Council, it will be published at <http://xmpp.org/extensions/> and announced on the <standards@xmpp.org> mailing list. Table of Contents
Appendices 1. IntroductionThe Jabber community has long acknowledged the need for privacy and security features in a well-rounded instant messaging system. Unfortunately, finding a consensus solution to the problem of end-to-end encryption is still not really solved. Lots of people are using Off-the-Record Communication [1]. This specification documents OTR as it is used in XMPP today. This document is not intended to present a standard, because more complete solutions are being investigated. 2. NegotiationNegotiation and encrypted content goes over normal <message/> stanzas in the <body/> child. Example 1. Requests to start OTR <message to='reat...@jabber.org/jarl' from='pgmill...@jabber.org/wj_dev2'> <body>?OTRv23? If you can read this, you don't support OTR.</body> </message> 3. EncryptingExample 2. An encrypted message stanza <message to='reat...@jabber.org/jarl' from='pgmill...@jabber.org/wj_dev2'> <body>?OTR:AAEDTmdnbnB4IG5nIHFuamEhCg==.</body> </message> It is considered polite to include an unencrypted message <body/>, but this is not possible in OTR due to the use of the <body/> for carrying the encrypted payload. 4. Security ConsiderationsThe method described herein has the following security issues:
5. Other Known IssuesIn addition to the security considerations listed above, there are several other known issues with this method:
6. IANA ConsiderationsThis document requires no interaction with the Internet Assigned Numbers Authority (IANA) [3]. 7. XMPP Registrar ConsiderationsThis document requires no interaction with the XMPP Registrar. AppendicesAppendix A: Document Information
Series: XEP Appendix B: Author InformationKim Alvefur
Email:
z...@zash.se Appendix C: Legal NoticesCopyrightThis XMPP Extension Protocol is copyright © 1999 - 2014 by the XMPP Standards Foundation (XSF).PermissionsPermission is hereby granted, free of charge, to any person obtaining a copy of this specification (the "Specification"), to make use of the Specification without restriction, including without limitation the rights to implement the Specification in a software program, deploy the Specification in a network service, and copy, modify, merge, publish, translate, distribute, sublicense, or sell copies of the Specification, and to permit persons to whom the Specification is furnished to do so, subject to the condition that the foregoing copyright notice and this permission notice shall be included in all copies or substantial portions of the Specification. Unless separate permission is granted, modified works that are redistributed shall not contain misleading information regarding the authors, title, number, or publisher of the Specification, and shall not claim endorsement of the modified works by the authors, any organization or project to which the authors belong, or the XMPP Standards Foundation.Disclaimer of Warranty## NOTE WELL: This Specification is provided on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, express or implied, including, without limitation, any warranties or conditions of TITLE, NON-INFRINGEMENT, MERCHANTABILITY, or FITNESS FOR A PARTICULAR PURPOSE. ##Limitation of LiabilityIn no event and under no legal theory, whether in tort (including negligence), contract, or otherwise, unless required by applicable law (such as deliberate and grossly negligent acts) or agreed to in writing, shall the XMPP Standards Foundation or any author of this Specification be liable for damages, including any direct, indirect, special, incidental, or consequential damages of any character arising from, out of, or in connection with the Specification or the implementation, deployment, or other use of the Specification (including but not limited to damages for loss of goodwill, work stoppage, computer failure or malfunction, or any and all other commercial damages or losses), even if the XMPP Standards Foundation or such author has been advised of the possibility of such damages.IPR ConformanceThis XMPP Extension Protocol has been contributed in full conformance with the XSF's Intellectual Property Rights Policy (a copy of which can be found at <http://xmpp.org/about-xmpp/xsf/xsf-ipr-policy/> or obtained by writing to XMPP Standards Foundation, 1899 Wynkoop Street, Suite 600, Denver, CO 80202 USA).Appendix D: Relation to XMPPThe Extensible Messaging and Presence Protocol (XMPP) is defined in the XMPP Core (RFC 6120) and XMPP IM (RFC 6121) specifications contributed by the XMPP Standards Foundation to the Internet Standards Process, which is managed by the Internet Engineering Task Force in accordance with RFC 2026. Any protocol defined in this document has been developed outside the Internet Standards Process and is to be understood as an extension to XMPP rather than as an evolution, development, or modification of XMPP itself. Appendix E: Discussion VenueThe primary venue for discussion of XMPP Extension Protocols is the <standards@xmpp.org> discussion list. Discussion on other xmpp.org discussion lists might also be appropriate; see <http://xmpp.org/about/discuss.shtml> for a complete list. Errata can be sent to <edi...@xmpp.org>. Appendix F: Requirements ConformanceThe following requirements keywords as used in this document are to be interpreted as described in RFC 2119: "MUST", "SHALL", "REQUIRED"; "MUST NOT", "SHALL NOT"; "SHOULD", "RECOMMENDED"; "SHOULD NOT", "NOT RECOMMENDED"; "MAY", "OPTIONAL". Appendix G: Notes1. Off-the-Record Communication, or, Why Not to Use PGP <http://www.cypherpunks.ca/otr/otr-codecon.pdf> <http://www.cypherpunks.ca/otr/otr-wpes.pdf>. 2. XEP-0280: Message Carbons <http://xmpp.org/extensions/xep-0280.html>. 3. The Internet Assigned Numbers Authority (IANA) is the central coordinator for the assignment of unique parameter values for Internet protocols, such as port numbers and URI schemes. For further information, see <http://www.iana.org/>. Appendix H: Revision HistoryNote: Older versions of this specification might be available at http://xmpp.org/extensions/attic/ Version 0.1 (2013-12-20)First draft. (ka)
END |
<?xml version='1.0' encoding='UTF-8'?>
<!DOCTYPE xep SYSTEM 'xep.dtd' [
<!ENTITY % ents SYSTEM 'xep.ent'>
%ents;
]>
<?xml-stylesheet type='text/xsl' href='xep.xsl'?>
<xep>
<header>
<title>Current OTR Usage in XMPP</title>
<abstract>This document outlines the current usage of OTR for encrypted messaging.</abstract>
&LEGALNOTICE;
<number>xxxx</number>
<status>ProtoXEP</status>
<type>Historical</type>
<sig>Standards</sig>
<dependencies>
<spec>XMPP Core</spec>
<spec>OTR spec?</spec>
</dependencies>
<supersedes/>
<supersededby/>
<shortname>otr</shortname>
&zash;
<revision>
<version>0.1</version>
<date>2013-12-20</date>
<initials>ka</initials>
<remark>First draft.</remark>
</revision>
</header>
<section1 topic='Introduction' anchor='intro'>
<p>
The Jabber community has long acknowledged the need for privacy and security features in a well-rounded instant messaging system.
Unfortunately, finding a consensus solution to the problem of end-to-end encryption is still not really solved.
Lots of people are using &otr;.
This specification documents OTR as it is used in XMPP today.
This document is not intended to present a standard, because more complete solutions are being investigated.
</p>
</section1>
<section1 topic='Negotiation' anchor='negotiation'>
<p>Negotiation and encrypted content goes over normal &MESSAGE; stanzas in the &BODY; child.</p>
<example caption='Requests to start OTR'><![CDATA[
<message to='reat...@jabber.org/jarl' from='pgmill...@jabber.org/wj_dev2'>
<body>?OTRv23? If you can read this, you don't support OTR.</body>
</message>
]]></example>
</section1>
<section1 topic='Encrypting' anchor='encrypting'>
<example caption='An encrypted message stanza'><![CDATA[
<message to='reat...@jabber.org/jarl' from='pgmill...@jabber.org/wj_dev2'>
<body>?OTR:AAEDTmdnbnB4IG5nIHFuamEhCg==.</body>
</message>
]]></example>
<p>It is considered polite to include an unencrypted message &BODY;, but this is not possible in OTR due to the use of the &BODY; for carrying the encrypted payload.</p>
</section1>
<section1 topic='Security Considerations' anchor='security'>
<p>The method described herein has the following security issues:</p>
<ul>
<li>No encryption of complete stanzas</li>
<li>Non-body payloads are not secured</li>
<li>Anything else?</li>
</ul>
</section1>
<section1 topic='Other Known Issues' anchor='issues'>
<p>In addition to the security considerations listed above, there are several other known issues with this method:</p>
<ul>
<li>Gets messy with multiple resources or &xep0280;.</li>
<li>Not integrated with XMPP.</li>
<li>Does not work with Offline messages or archives. (Some may consider this a good thing)</li>
</ul>
</section1>
<section1 topic='IANA Considerations' anchor='iana'>
<p>This document requires no interaction with &IANA;.</p>
</section1>
<section1 topic='XMPP Registrar Considerations' anchor='registrar'>
<p>This document requires no interaction with the XMPP Registrar.</p>
</section1>
</xep>
signature.asc
Description: OpenPGP digital signature
