Group Messaging E2EE
Membership authentication in groups
More is Less: How Group Chats Weaken the Security of In- stant Messengers Signal, WhatsApp, and Threema
Efficient Post-Compromise Security Beyond One Group
video: What's Up With Group Messaging?
blog: Better Encrypted Group Chat
Randomly generate your sender key
For every user in the group, encrypt your sender key with your pair key that you share with that user
Send every user their encrypted copy of your sender ket as an auxiliary message
Send an application message m:
Encrypts m with her sender key precisely once
Broadcasts the ciphertext to the group
Removal members and PCS don't work.
Removing needs O(N^2) communication cost same as setup phase because sender keys need to be updated.
Signal Sender Keys: Why it works and which is the common key at the end?
On Ends-to-Ends Encryption
TreeKEM: Asynchronous Decentralized Key Management for Large Dynamic Groups
A Rust implementation of the Message Layer Security group messaging protocol
Messaging Layer Security (mls)
Security Analysis and Improvements for the IETF MLS Standard for Group Messaging
Keep the Dirt: Tainted TreeKEM, an Efficient and Provably Secure Continuous Group Key Agreement Protocol
RWC20 tweet about mls