Subject: [saag] Confidential Group Communications

From: "Shaun Cooley (shcooley)" <[email-masked]>
Date: Thu, 5 Nov 2015 07:46:27 +0000

This is a follow up to my 60 second speed pitch from today's open session...

Questions: 
 - How can we represent and manage group membership in a way that is verifiable, tamper-proof, and practical in both centralized and decentralized topologies?
 - How do we share encryption keys for resources shared within the group?
 - How do we federate group membership and keys between a single group that spans multiple central authorities?
 - How do we have groups that consist of a mix of both centralized and decentralized users?

Our first draft, draft-abiggs-saag-primitives-for-conf-group-comms-01, defines two primitives that can be used to answer the above questions.  Specifically, a Group Membership Block Chain (GMBC) and a Group Key (GK).  Additionally, the draft defines both a centralized and decentralized model, introduces the concept of a "curator" for the centralized model, and provides nominal sequences for each model.

A Group Membership Block Chain (GMBC) is.
 - a ledger of group membership updates over time
- a publicly verifiable record of membership and policy
- tamper-proof based on public key authentication
- supports zero-conflict centralized topologies
- supports conflict-resolution in decentralized topologies

A Group Key (GK) is.
 - a standard JOSE JSON representation that wraps a content key with the public keys of each other GMBC group members.
 - an object that can be shared openly without compromising confidentiality

Our second draft, draft-abiggs-saag-key-management-service-03, provides details of a centralized confidential group communication model that is derived from the primitives listed above and lists communication sequences for HTTP file sharing and XMPP.

We will publish a third draft in the near future to further detail the use of the primitives in a decentralized model.

If anyone else is working in this area, we'd like to chat and hopefully collaborate!  Please reach out to me via email or find me in Yokohama tonight or tomorrow.  I'll be at the Intercontinental lobby bar after Bits-n-Bites tonight.

The drafts:
 - https://tools.ietf.org/html/draft-abiggs-saag-primitives-for-conf-group-comms-01
 - https://tools.ietf.org/html/draft-abiggs-saag-key-management-service-03

I also mentioned a related draft by Martin Thomson and Adam Roach, which can be found at:
 - https://tools.ietf.org/html/draft-thomson-xmpp-secure-00

-Shaun