Difference between revisions of "XMPP E2E Security"
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OMEMO is based on the Signal double ratchet and provides forward secrecy, compatibility with history retrieval for devices that are already part of the ratchet, and a number of other benefits over legacy encryption mechanisms. It has had an independent third party audit (see related links at bottom). | OMEMO is based on the Signal double ratchet and provides forward secrecy, compatibility with history retrieval for devices that are already part of the ratchet, and a number of other benefits over legacy encryption mechanisms. It has had an independent third party audit (see related links at bottom). | ||
== XEP-0373: OpenPGP for XMPP / XEP-0374: OpenPGP for XMPP Instant Messaging == | |||
'''Recommendation:''' Exploratory implementations are encouraged. | |||
The OpenPGP for XMPP (OX) specification currently consists of a baseline specification: [https://xmpp.org/extensions/xep-0373.html XEP-0373] and a profile for Instant Messaging specification [https://xmpp.org/extensions/xep-0374.html XEP-0374]. It is under active development and thus subject to change although can be considered pretty stable for the major parts. | |||
OX attempts to fix the various security design flaws of XEP-0027, and additionally specifies features like "arbitrary extension element" verification and protection. | |||
Implementations are available for Gajim and Smack. | |||
== XEP-0027 (legacy PGP) == | == XEP-0027 (legacy PGP) == | ||
Revision as of 08:03, 17 October 2018
This page aims to provide an overview, comparison and evaluation of existing and proposed end-to-end security solutions for XMPP, after providing the characteristings of the XMPP setting with regard to communication and the security of it.
Proposals
XEP-0384: OMEMO Encryption (Signal / Text Secure)
Recommendation: Implement.
OMEMO is based on the Signal double ratchet and provides forward secrecy, compatibility with history retrieval for devices that are already part of the ratchet, and a number of other benefits over legacy encryption mechanisms. It has had an independent third party audit (see related links at bottom).
XEP-0373: OpenPGP for XMPP / XEP-0374: OpenPGP for XMPP Instant Messaging
Recommendation: Exploratory implementations are encouraged.
The OpenPGP for XMPP (OX) specification currently consists of a baseline specification: XEP-0373 and a profile for Instant Messaging specification XEP-0374. It is under active development and thus subject to change although can be considered pretty stable for the major parts.
OX attempts to fix the various security design flaws of XEP-0027, and additionally specifies features like "arbitrary extension element" verification and protection.
Implementations are available for Gajim and Smack.
XEP-0027 (legacy PGP)
Recommendation: do not implement unless compatibility with legacy clients is required.
One of the first proposals for end-to-end security is based on PGP and described in XEP-0027.
The way XEP-0027 uses PGP, it doesn't provide protection from replay attacks. It also only encrypts messages and doesn't sign them, so they could be replaced with different correctly encrypted messages on the wire.(Source: chat in xsf@m.x.o) Thus it has been obsoleted by the XMPP Council in it's meeting on 2014-03-12.
OTR (Off-the-record Messaging)
Recommendation: do not implement unless compatibility with legacy clients is required. .
OTR is a crypto protocol, specifically designed to secure instant messaging conversations. Its usage in XMPP is documented (but not standardized) in https://xmpp.org/extensions/xep-0364.html
Comparative Overview
| Proposal | Security property | Communication patterns | Compatibility with XMPP | |||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Authenticity | Integrity | Encryption | Forward secrecy | Malleability | One-to-One | Groupchat | Offline messages | Multiple resources | Discovery of support | |
| OMEMO (XEP-0384) | Yes | Except in the case of a malicious authenticated device | Yes | Yes | By authenticated devices | Yes | Yes (Non-anonymous only) | Yes | Yes | Yes |
| Legacy PGP (XEP-0027) | No (messages only encrypted, not signed) | No | Yes | No | N/A | Yes | No | Yes | Yes (if same keypair at all resources) | No |
| OTR | Yes | Yes | Yes | Yes | Yes | Yes | No | No | No | No |
Related Documents
- https://developer.pidgin.im/wiki/EndToEndXMPPCrypto
- http://trevp.net/talk_2014_04_02.pdf
- https://conversations.im/omemo/audit.pdf
Discussion
If you have any questions or comments regarding this page, please join the XSF chatroom at xsf@muc.xmpp.org.