From de92a8c11f67650e0e0e254e672fb9af2f41cb34 Mon Sep 17 00:00:00 2001 From: Daniel Gultsch Date: Fri, 2 Jun 2017 15:30:11 +0200 Subject: [PATCH 1/6] XEP-0384: switch to 'siacs' namespace and use SignalProtocol --- xep-0384.xml | 83 +++++++++++++++++++++++++++++----------------------- 1 file changed, 46 insertions(+), 37 deletions(-) diff --git a/xep-0384.xml b/xep-0384.xml index 29d76c94..7d388d91 100644 --- a/xep-0384.xml +++ b/xep-0384.xml @@ -27,6 +27,15 @@ andy@strb.org andy@strb.org + + 0.2 + 2017-06-02 + dg + +

Depend on SignalProtocol instead of Olm.

+

Changed to eu.siacs.conversations.axolotl Namespace which is currently used in the wild

+ + 0.1 2016-12-07 @@ -63,17 +72,19 @@ external complexity.

- This XEP defines a protocol that leverages &olm; encryption to provide + This XEP defines a protocol that leverages the SignalProtocol encryption to provide multi-end to multi-end encryption, allowing messages to be synchronized - securely across multiple clients, even if some of them are offline. Olm + securely across multiple clients, even if some of them are offline. The SignalProtocol is a cryptographic double ratched protocol based on work by Trevor Perrin - and Moxie Marlinspike first published as the Axolotl protocol. + and Moxie Marlinspike first published as the Axolotl protocol. The protocol is not fully + documented in public domain and only exists in GPLv3-licensed implementations maintained + by OpenWhisperSystems.

The general idea behind this protocol is to maintain separate, - long-standing Olm-encrypted sessions with each device of each contact + long-standing SignalProtocol-encrypted sessions with each device of each contact (as well as with each of our other devices), which are used as secure key transport channels. In this scheme, each message is encrypted with a fresh, randomly generated encryption key. An encrypted header is added to @@ -87,14 +98,14 @@

As the encrypted payload is common to all recipients, it only has to be - included once, reducing overhead. Furthermore, Olm's transparent handling + included once, reducing overhead. Furthermore, SignalProtocols’s transparent handling of messages that were lost or received out of order, as well as those sent while the recipient was offline, is maintained by this protocol. As a result, in combination with &xep0280; and &xep0313;, the desired property of inter-client history synchronization is achieved.

- OMEMO currently uses version 1 Olm protocol. Instead of an Axolotl key + OMEMO currently uses version 3 SignalProtocol. Instead of an Signal key server, &xep0163; (PEP) is used to publish key data.

@@ -111,7 +122,7 @@
Device
A communication end point, i.e. a specific client instance
 -
OMEMO element
An <encrypted> element in the urn:xmpp:omemo:0 namespace. Can be either MessageElement or a KeyTransportElement
 +
OMEMO element
An <encrypted> element in the eu.siacs.conversations.axolotl namespace. Can be either MessageElement or a KeyTransportElement
MessageElement
An OMEMO element that contains a chat message. Its <payload>, when decrypted, corresponds to a <message>'s <body>.
KeyTransportElement
An OMEMO element that does not have a <payload>. It contains a fresh encryption key, which can be used for purposes external to this XEP.
Bundle
A collection of publicly accessible data that can be used to build a session with a device, namely its public IdentityKey, a signed PreKey with corresponding signature, and a list of (single use) PreKeys.
 @@ -120,12 +131,12 @@
- +
IdentityKey
Per-device public/private key pair used to authenticate communications
PreKey
A Diffie-Hellman public key, published in bulk and ahead of time
 -
PreKeyOlmMessage
An encrypted message that includes the initial key exchange. This is used to transparently build sessions with the first exchanged message.
 -
OlmMessage
An encrypted message
 +
PreKeySignalMessage
An encrypted message that includes the initial key exchange. This is used to transparently build sessions with the first exchanged message.
 +
SignalMessage
An encrypted message
@@ -139,16 +150,16 @@

-

In order to determine whether a given contact has devices that support OMEMO, the devicelist node in PEP is consulted. Devices MUST subscribe to 'urn:xmpp:omemo:0:devicelist' via PEP, so that they are informed whenever their contacts add a new device. They MUST cache the most up-to-date version of the devicelist.

+

In order to determine whether a given contact has devices that support OMEMO, the devicelist node in PEP is consulted. Devices MUST subscribe to 'eu.siacs.conversations.axolotl.devicelist' via PEP, so that they are informed whenever their contacts add a new device. They MUST cache the most up-to-date version of the devicelist.

- + - + @@ -162,9 +173,9 @@ - + - + @@ -178,9 +189,9 @@ - + - + BASE64ENCODED... @@ -216,10 +227,10 @@ to='juliet@capulet.lit' id='fetch1'> - + ]]> -

A random preKeyPublic entry is selected, and used to build an Olm session.

+

A random preKeyPublic entry is selected, and used to build an SignalProtocol session.

@@ -230,15 +241,15 @@ 128 bit) are concatenated and for each intended recipient device, i.e. both own devices as well as devices associated with the contact, the result of this concatenation is encrypted using the corresponding - long-standing Olm session. Each encrypted payload key/authentication tag + long-standing SignalProtocol session. Each encrypted payload key/authentication tag tuple is tagged with the recipient device's ID. The key element MUST be - tagged with a prekey attribute set to true if a PreKeyOlmMessage is being + tagged with a prekey attribute set to true if a PreKeySignalMessage is being used. This is all serialized into a MessageElement, which is transmitted in a <message> as follows:

- +
BASE64ENCODED... BASE64ENCODED... @@ -258,14 +269,14 @@ SHOULD have at least 128 bit) are concatenated and for each intended recipient device, i.e. both own devices as well as devices associated with the contact, this key is encrypted using the corresponding - long-standing Olm session. Each encrypted payload key/authentication tag + long-standing SignalProtocol session. Each encrypted payload key/authentication tag tuple is tagged with the recipient device's ID. The key element MUST be - tagged with a prekey attribute set to true if a PreKeyOlmMessage is being + tagged with a prekey attribute set to true if a PreKeySignalMessage is being used This is all serialized into a KeyTransportElement, omitting the <payload> as follows:

+
BASE64ENCODED... BASE64ENCODED... @@ -276,25 +287,24 @@

This KeyTransportElement can then be sent over any applicable transport mechanism.

-

When an OMEMO element is received, the client MUST check whether there is a <key> element with an rid attribute matching its own device ID. If this is not the case, the element MUST be silently discarded. If such an element exists, the client checks whether the element's contents are a PreKeyOlmMessage.

+

When an OMEMO element is received, the client MUST check whether there is a <key> element with an rid attribute matching its own device ID. If this is not the case, the element MUST be silently discarded. If such an element exists, the client checks whether the element's contents are a PreKeySignalMessage.

If this is the case, a new session is built from this received element. The client SHOULD then republish their bundle information, replacing the used PreKey, such that it won't be used again by a different client. If the client already has a session with the sender's device, it MUST replace this session with the newly built session. The client MUST delete the private key belonging to the PreKey after use.

-

If the element's contents are a OlmMessage, and the client has a session with the sender's device, it tries to decrypt the OlmMessage using this session. If the decryption fails or if the element's contents are not a OlmMessage either, the OMEMO element MUST be silently discarded.

+

If the element's contents are a SignalMessage, and the client has a session with the sender's device, it tries to decrypt the SignalMessage using this session. If the decryption fails or if the element's contents are not a SignalMessage either, the OMEMO element MUST be silently discarded.

If the OMEMO element contains a <payload>, it is an OMEMO message element. The client tries to decrypt the base64 encoded contents using the key and the authentication tag extracted from the <key> element. If the decryption fails, the client MUST silently discard the OMEMO message. If it succeeds, the decrypted contents are treated as the <body> of the received message.

If the OMEMO element does not contain a <payload>, the client has received a KeyTransportElement. The key extracted from the <key> element can then be used for other purposes (e.g. encrypted file transfer).

Before publishing a freshly generated Device ID for the first time, a device MUST check whether that Device ID already exists, and if so, generate a new one.

-

Clients SHOULD NOT immediately fetch the bundle and build a session as soon as a new device is announced. Before the first message is exchanged, the contact does not know which PreKey has been used (or, in fact, that any PreKey was used at all). As they have not had a chance to remove the used PreKey from their bundle announcement, this could lead to collisions where both Alice and Bob pick the same PreKey to build a session with a specific device. As each PreKey SHOULD only be used once, the party that sends their initial PreKeyOlmMessage later loses this race condition. This means that they think they have a valid session with the contact, when in reality their messages MAY be ignored by the other end. By postponing building sessions, the chance of such issues occurring can be drastically reduced. It is RECOMMENDED to construct sessions only immediately before sending a message.

-

As there are no explicit error messages in this protocol, if a client does receive a PreKeyOlmMessage using an invalid PreKey, they SHOULD respond with a KeyTransportElement, sent in a <message> using a PreKeyOlmMessage. By building a new session with the original sender this way, the invalid session of the original sender will get overwritten with this newly created, valid session.

-

If a PreKeyOlmMessage is received as part of a &xep0313; catch-up and used to establish a new session with the sender, the client SHOULD postpone deletion of the private key corresponding to the used PreKey until after MAM catch-up is completed. If this is done, the client MUST then also send a KeyTransportMessage using a PreKeyOlmMessage before sending any payloads using this session, to trigger re-keying. (as above) This practice can mitigate the previously mentioned race condition by preventing message loss.

+

Clients SHOULD NOT immediately fetch the bundle and build a session as soon as a new device is announced. Before the first message is exchanged, the contact does not know which PreKey has been used (or, in fact, that any PreKey was used at all). As they have not had a chance to remove the used PreKey from their bundle announcement, this could lead to collisions where both Alice and Bob pick the same PreKey to build a session with a specific device. As each PreKey SHOULD only be used once, the party that sends their initial PreKeySignalMessage later loses this race condition. This means that they think they have a valid session with the contact, when in reality their messages MAY be ignored by the other end. By postponing building sessions, the chance of such issues occurring can be drastically reduced. It is RECOMMENDED to construct sessions only immediately before sending a message.

+

As there are no explicit error messages in this protocol, if a client does receive a PreKeySignalMessage using an invalid PreKey, they SHOULD respond with a KeyTransportElement, sent in a <message> using a PreKeySignalMessage. By building a new session with the original sender this way, the invalid session of the original sender will get overwritten with this newly created, valid session.

+

If a PreKeySignalMessage is received as part of a &xep0313; catch-up and used to establish a new session with the sender, the client SHOULD postpone deletion of the private key corresponding to the used PreKey until after MAM catch-up is completed. If this is done, the client MUST then also send a KeyTransportMessage using a PreKeySignalMessage before sending any payloads using this session, to trigger re-keying. (as above) This practice can mitigate the previously mentioned race condition by preventing message loss.

As the asynchronous nature of OMEMO allows decryption at a later time to currently offline devices client SHOULD include a &xep0334; <store /> hint in their OMEMO messages. Otherwise, server implementations of &xep0313; will generally not retain OMEMO messages, since they do not contain a <body />

- The Olm library's reference implementation (and presumably its ports to - various other platforms) uses a trust model that doesn't work very well with + The SignalProtocol-library uses a trust model that doesn't work very well with OMEMO. For this reason it may be desirable to have the library consider all keys trusted, effectively disabling its trust management. This makes it necessary to implement trust handling oneself. @@ -305,7 +315,7 @@

When prompting the user for a trust decision regarding a key, the client SHOULD present the user with a fingerprint in the form of a hex string, QR code, or other unique representation, such that it can be compared by the user.

While it is RECOMMENDED that clients postpone private key deletion until after MAM catch-up and this standards mandates that clients MUST NOT use duplicate-PreKey sessions for sending, clients MAY delete such keys immediately for security reasons. For additional information on potential security impacts of this decision, refer to Menezes, Alfred, and Berkant Ustaoglu. "On reusing ephemeral keys in Diffie-Hellman key agreement protocols." International Journal of Applied Cryptography 2, no. 2 (2010): 154-158..

- In order to be able to handle out-of-order messages, the Olm stack has to + In order to be able to handle out-of-order messages, the SignalProtocol stack has to cache the keys belonging to "skipped" messages that have not been seen yet. It is up to the implementor to decide how long and how many of such keys to keep around. @@ -318,9 +328,8 @@

This specification defines the following XMPP namespaces:

    -
  • urn:xmpp:omemo:0
    • +
  • eu.siacs.conversations.axolotl
-

The ®ISTRAR; shall include the foregoing namespace in its registry at &NAMESPACES;, as goverened by &xep0053;.

&NSVER; @@ -330,8 +339,8 @@ + targetNamespace="eu.siacs.conversations.axolotl" + xmlns="eu.siacs.conversations.axolotl"> From 8d6bb1875abfa5b508141d2ba0e33e888b83ca58 Mon Sep 17 00:00:00 2001 From: Andreas Straub Date: Wed, 5 Jul 2017 13:41:14 +0200 Subject: [PATCH 2/6] XEP-0384: clarify wording --- xep-0384.xml | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/xep-0384.xml b/xep-0384.xml index 7d388d91..e86ebefc 100644 --- a/xep-0384.xml +++ b/xep-0384.xml @@ -76,9 +76,11 @@ multi-end to multi-end encryption, allowing messages to be synchronized securely across multiple clients, even if some of them are offline. The SignalProtocol is a cryptographic double ratched protocol based on work by Trevor Perrin - and Moxie Marlinspike first published as the Axolotl protocol. The protocol is not fully - documented in public domain and only exists in GPLv3-licensed implementations maintained - by OpenWhisperSystems. + and Moxie Marlinspike first published as the Axolotl protocol. While the + protocol itself has specifications in the public domain, the + protobuf-based wire format of the signal protocol is not fully + documented. The signal protocol currently only exists in GPLv3-licensed + implementations maintained by OpenWhisperSystems.

From 3cecd09eb6ba1580e649dd1beb4870c657a8d4b4 Mon Sep 17 00:00:00 2001 From: Andreas Straub Date: Wed, 5 Jul 2017 14:25:33 +0200 Subject: [PATCH 3/6] XEP-0384: fix typos --- xep-0384.xml | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/xep-0384.xml b/xep-0384.xml index e86ebefc..a06ee046 100644 --- a/xep-0384.xml +++ b/xep-0384.xml @@ -107,7 +107,7 @@ of inter-client history synchronization is achieved.

- OMEMO currently uses version 3 SignalProtocol. Instead of an Signal key + OMEMO currently uses version 3 SignalProtocol. Instead of a Signal key server, &xep0163; (PEP) is used to publish key data.

@@ -232,7 +232,7 @@ ]]> -

A random preKeyPublic entry is selected, and used to build an SignalProtocol session.

+

A random preKeyPublic entry is selected, and used to build a SignalProtocol session.

From faa981f499c65c830741a85667ca2871416ddf3a Mon Sep 17 00:00:00 2001 From: Emmanuel Gil Peyrot Date: Mon, 17 Jul 2017 21:43:00 +0100 Subject: [PATCH 4/6] XEP-0319: Make the schema more precise about a date being a xs:dateTime. --- xep-0319.xml | 8 +++++++- 1 file changed, 7 insertions(+), 1 deletion(-) diff --git a/xep-0319.xml b/xep-0319.xml index 26a5712a..966947a0 100644 --- a/xep-0319.xml +++ b/xep-0319.xml @@ -24,6 +24,12 @@ idle &tobias; + + 1.0.1 + 2017-07-17 + egp +

Make the schema more precise about a date being a xs:dateTime.

+ 1.0 2015-04-02 @@ -98,7 +104,7 @@ - + From 25d0dba2718e2dfd1744cdde6f5bde0892872b3e Mon Sep 17 00:00:00 2001 From: Thiago Camargo Date: Fri, 15 Sep 2017 17:39:32 +0200 Subject: [PATCH 5/6] Added Support for TURN Added Support for TURN Discovery and Credentials Retrieval --- xep-0278.xml | 101 +++++++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 98 insertions(+), 3 deletions(-) diff --git a/xep-0278.xml b/xep-0278.xml index f6e9255e..7737995a 100644 --- a/xep-0278.xml +++ b/xep-0278.xml @@ -3,6 +3,8 @@ + + %ents; @@ -32,6 +34,12 @@ thiago@xmppjingle.com barata7@gmail.com + + 0.2 + 2017-09-14 + tc +

Added TURN Credentials Service Support.

 + 0.2 2011-06-21 @@ -115,6 +123,7 @@ All signalling, request, response and publishing is done via XMPP, not requiring + @@ -194,6 +203,34 @@ All signalling, request, response and publishing is done via XMPP, not requiring ]]>

After receiving the &CHANNEL; the requester MUST send his stream to 'host' and 'localport' pair and send a &CANDIDATE; containing the 'host' and 'remoteport' values.

 + +

A Jingle Client can request volative TURN credentials, to be used in cases where connectivity check is a requirement. Like, for example, WebRTC. The concept and mechanism is quite similar to the RFC draft REST API For Access To TURN Services'.

+

TURN provides an access control mechanism described in &rfc5389;, where long-term credentials are provided as part of the TURN protocol. Therefore the credentials provided in this Jingle Nodes mechanism are time-limited, but SHOULD be used as long-term credentials, when authentication against a TURN Server. +

+

+ Note: There is no need to run TURN server or support within a Jingle Relay. This mechanism allows decoupled deployment of distributed TURN Servers, without the requirement of database based authentication. +

+ + + +]]> + + + +]]> + @@ -293,7 +330,7 @@ All signalling, request, response and publishing is done via XMPP, not requiring -

The &SERVICES; element MAY be empty or contain &RELAY; and/or &TRACKER; elements.

+

The &SERVICES; element MAY be empty or contain &RELAY;, &STUN; and/or &TRACKER; elements.

The attributes of the &RELAY; and &TRACKER; element are as follows.

@@ -323,6 +360,48 @@ All signalling, request, response and publishing is done via XMPP, not requiring
+ +

The attributes of the &TURN; element are as follows.

+ + + + + + + + + + + + + + + + + + + + + + + + + + +
AttributeDefinitionInclusion
ttlThe duration in seconds for which the provided credentials are valid.REQUIRED
uriThe TURN Server URI.REQUIRED
usernameThe username to be used on TURN authentication. THe recommended format is a colon-delimited concatenation of expiration timestamp and the requester bare JID.REQUIRED
passwordThe ppassword to be used on TURN authentication. Is the result of 'base64(hmac(secret_key, username))'. Where 'secret_key' is shared between the TURN server and entity providing the credentials.REQUIRED
+ +

The duration in seconds for which the provided credentials are valid. The usual and recommended value is 86400 seconds (one day).

+ + +

The TURN Server URI as described in I-D.petithuguenin-behave-turn-uris

+ + +

WebRTC's TURN request uses the 'username' value for its USERNAME and PASSWORD attributes, for the input to the MESSAGE-INTEGRITY hash.

+ + +

Along with 'username', WebRTC's TURN request uses the 'password' value for its USERNAME and PASSWORD attributes, for the input to the MESSAGE-INTEGRITY hash.

+ +

To advertise its support for the Jingle Nodes support, when replying to &xep0030; information requests an entity MUST return URNs for any version of this protocol that the entity supports -- e.g., "http://jabber.org/protocol/jinglenodes" for this version&VNOTE;.

@@ -342,8 +421,9 @@ All signalling, request, response and publishing is done via XMPP, not requiring to='romeo@montague.lit/orchard' type='result'> - - + + + ]]> @@ -356,6 +436,10 @@ All signalling, request, response and publishing is done via XMPP, not requiring Note: This use case is also similar to a Jingle to SIP Interoperability Service.

+ +

A Jingle Client that uses WebRTC, therefore requiring a TURN Server and its credentials to successfully alocate channels. This specification describes a simple way of discovering TURN Services and retrieving credentials to successfully allocate channels. + This also simplifies deployment and distribution of TURN servers, since its stateless authentication does not require connectivity to database authoriztion services.

+

A Jingle Client with STUN support but no TURN support can use Relay Node Services as the fallback candidate instead of a TURN candidate. For instance, after a connectivity check proccess, none of the direct candidates worked. The Client can use the Relay Node Candidate as the fallback candidate(the lowest priority candidate).

 @@ -420,6 +504,13 @@ All signalling, request, response and publishing is done via XMPP, not requiring + + + + + + + @@ -435,6 +526,10 @@ All signalling, request, response and publishing is done via XMPP, not requiring type='serviceElementType' minOccurs='0' maxOccurs='unbounded'/> + From f9e12ba4a055c0dc06b4986d3e95e4c95c728fb9 Mon Sep 17 00:00:00 2001 From: Jonas Wielicki Date: Fri, 15 Sep 2017 18:19:39 +0200 Subject: [PATCH 6/6] XEP-0278: un-defer after update --- xep-0278.xml | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/xep-0278.xml b/xep-0278.xml index 7737995a..1a678e22 100644 --- a/xep-0278.xml +++ b/xep-0278.xml @@ -16,7 +16,7 @@ This documents specifies how Jingle Clients can interact with Jingle Relay Nodes Services and how XMPP entities can provide, search and list available Jingle Relay Nodes. &LEGALNOTICE; 0278 - Deferred + Experimental Standards Track Standards Council