Difference between revisions of "XMPP E2E Security"

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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.
 
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.
  
= Security properties =
+
= Proposals =
  
# [http://en.wikipedia.org/wiki/Information_security#Authenticity Authenticity]
+
== XEP-0384: OMEMO Encryption (Signal / Text Secure) ==
# [http://en.wikipedia.org/wiki/Information_security#Integrity Integrity]
+
# [http://en.wikipedia.org/wiki/Encryption Encryption]
+
# [http://en.wikipedia.org/wiki/Forward_secrecy Forward secrecy]
+
# [http://en.wikipedia.org/wiki/Deniable_encryption#Malleable_encryption Malleable encryption]
+
  
 +
'''Recommendation:''' Implement if you need forward secrecy.
  
= Proposals =
+
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-0384: OMEMO Encryption (Signal / Text Secure) ==
+
== XEP-0373: OpenPGP for XMPP / XEP-0374: OpenPGP for XMPP Instant Messaging ==
 +
 
 +
'''Recommendation:''' Exploratory implementations are encouraged.
  
'''Recommendation:''' Implement.
+
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 regarding most parts.
  
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 https://conversations.im/omemo/audit.pdf).
+
OX attempts to fix the various security design flaws of XEP-0027, and additionally specifies features like "arbitrary extension element" verification and protection.
  
== XEP-0027 (PGP) ==
+
Implementations are available for Gajim and Smack, and have been successfully tested against each other for interoperability.
  
'''Recommendation:''' implement only if compatibility with legacy clients is required.
+
== XEP-0027 (Legacy OpenPGP) ==
 +
 
 +
'''Recommendation:''' Do '''not implement''', as the specification has [https://xmpp.org/extensions/xep-0027.html#security serious security issues].
  
 
One of the first proposals for end-to-end security is based on [http://en.wikipedia.org/wiki/Pretty_Good_Privacy PGP] and described in [http://xmpp.org/extensions/xep-0027.html XEP-0027].
 
One of the first proposals for end-to-end security is based on [http://en.wikipedia.org/wiki/Pretty_Good_Privacy PGP] and described in [http://xmpp.org/extensions/xep-0027.html XEP-0027].
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== OTR (Off-the-record Messaging) ==
 
== OTR (Off-the-record Messaging) ==
  
'''Recommendation:''' implement only if compatibility with legacy clients is required.
+
'''Recommendation:''' do not implement unless compatibility with legacy clients is required.
 
+
.
[https://otr.cypherpunks.ca/ OTR] is a crypto protocol, specifically designed to secure instant messaging conversations.
+
 
+
== SCIMP ( Silent Circle Instant Messaging Protocol) ==
+
 
+
'''Recommendation:''' not standardized, do not implement.
+
  
[https://silentcircle.com/web/scimp-protocol/ SCIMP] is the cryptographic protocol used by Silent Text, which enables private conversations over standard XMPP.
+
[https://otr.cypherpunks.ca/ 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 =
 
= Comparative Overview =
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!colspan="5" |Security property
 
!colspan="5" |Security property
 
!colspan="2" |Communication patterns
 
!colspan="2" |Communication patterns
!colspan="4" |Compatibility with XMPP
+
!colspan="3" |Compatibility with XMPP
 
|-
 
|-
!Authenticity
+
![https://en.wikipedia.org/wiki/Digital_signature#Authentication Authenticity]
!Integrity
+
![https://en.wikipedia.org/wiki/Information_security#Integrity Integrity]
!Encryption  
+
![https://en.wikipedia.org/wiki/Encryption Encryption]
!Forward secrecy
+
![https://en.wikipedia.org/wiki/Forward_secrecy Forward secrecy]
!Malleable encryption
+
![https://en.wikipedia.org/wiki/Malleability_(cryptography) Malleability]
 
!One-to-One
 
!One-to-One
 
!Groupchat
 
!Groupchat
!Online chats
 
 
!Offline messages
 
!Offline messages
 
!Multiple resources
 
!Multiple resources
 
!Discovery of support
 
!Discovery of support
 
|-
 
|-
|XEP-0027
+
|OMEMO (XEP-0384)
|No (messages only encrypted, not signed)
+
|No
+
 
|Yes
 
|Yes
|No
+
|Except in the case of a malicious authenticated device
|N/A
+
 
|Yes
 
|Yes
|No
 
 
|Yes
 
|Yes
 +
|By authenticated devices
 
|Yes
 
|Yes
|Yes (if same keypair at all resources)
+
|Yes (Non-anonymous only)
|No
+
|-
+
|RFC 3923
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|-
+
|XEP-0200
+
 
|Yes
 
|Yes
 
|Yes
 
|Yes
 
|Yes
 
|Yes
 +
|-
 +
|XEP-0374: OpenPGP for XMPP Instant Messaging
 
|Yes
 
|Yes
 
|Yes
 
|Yes
 
|Yes
 
|Yes
 
|No
 
|No
|Yes (XEP-0116/XEP-217)
+
|N/A
|Yes (XEP-0187)
+
|No
+
 
|Yes
 
|Yes
|-
+
|Possible and planned, but currently unspecified
|XTLS
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|?
+
|-
+
|miller-e2e
+
|Optional (Nesting signature/encryption)
+
 
|Yes
 
|Yes
 
|Yes
 
|Yes
 +
|Yes
 +
|-
 +
|Legacy PGP (XEP-0027)
 +
|No (messages only encrypted, not signed)
 
|No
 
|No
 +
|Yes
 
|No
 
|No
|Yes
+
|N/A
|Possible
+
 
|Yes
 
|Yes
 
|No
 
|No
 
|Yes
 
|Yes
|Yes
+
|Yes (if same keypair at all resources)
 +
|No
 
|-
 
|-
 
|OTR
 
|OTR
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|Yes
 
|Yes
 
|No
 
|No
|Yes
 
 
|No
 
|No
 
|No
 
|No
 
|No
 
|No
|-
 
|TS
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|-
 
|SCIMP
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
|?
 
 
|}
 
|}
  
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* https://developer.pidgin.im/wiki/EndToEndXMPPCrypto
 
* https://developer.pidgin.im/wiki/EndToEndXMPPCrypto
 
* http://trevp.net/talk_2014_04_02.pdf
 
* http://trevp.net/talk_2014_04_02.pdf
 +
* https://conversations.im/omemo/audit.pdf
  
 
= Discussion =
 
= Discussion =
 
If you have any questions or comments regarding this page, please [xmpp:xsf@muc.xmpp.org?join join the XSF chatroom at xsf@muc.xmpp.org].
 
If you have any questions or comments regarding this page, please [xmpp:xsf@muc.xmpp.org?join join the XSF chatroom at xsf@muc.xmpp.org].
 +
 +
= Abandoned and Legacy E2EE specifications =
 +
 +
Those specifications are very likely not relevant any more. They either gained no adoption or where replaced in favor of newer specifications. They are listed here only for the sake of completeness.
 +
 +
== draft-miller-xmpp-e2e ==
 +
 +
https://datatracker.ietf.org/doc/draft-miller-xmpp-e2e/
 +
 +
== ESessions ==
 +
 +
https://xmpp.org/extensions/xep-0187.html
 +
https://xmpp.org/extensions/xep-0188.html
 +
 +
== RFC 3923: End-to-End Signing and Object Encryption for the Extensible Messaging and Presence Protocol (XMPP) ==
 +
 +
https://tools.ietf.org/html/rfc3923

Latest revision as of 09:37, 14 November 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 if you need forward secrecy.

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 regarding most 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, and have been successfully tested against each other for interoperability.

XEP-0027 (Legacy OpenPGP)

Recommendation: Do not implement, as the specification has serious security issues.

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
XEP-0374: OpenPGP for XMPP Instant Messaging Yes Yes Yes No N/A Yes Possible and planned, but currently unspecified 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

Discussion

If you have any questions or comments regarding this page, please join the XSF chatroom at xsf@muc.xmpp.org.

Abandoned and Legacy E2EE specifications

Those specifications are very likely not relevant any more. They either gained no adoption or where replaced in favor of newer specifications. They are listed here only for the sake of completeness.

draft-miller-xmpp-e2e

https://datatracker.ietf.org/doc/draft-miller-xmpp-e2e/

ESessions

https://xmpp.org/extensions/xep-0187.html https://xmpp.org/extensions/xep-0188.html

RFC 3923: End-to-End Signing and Object Encryption for the Extensible Messaging and Presence Protocol (XMPP)

https://tools.ietf.org/html/rfc3923