RCC 16 – Rich Communication Suite – End-to-End Encryption Specification

Version 4.0

This specification defines the procedures for supporting end-to-end encryption of RCS messages and other user-provided content based on the Messaging Layer Security (MLS) protocol. It defines the overall concepts for applying MLS in the context of RCS, including the interactions between client providers, and defines the client procedures for encrypting and decrypting the RCS content. This new version brings in the lessons learnt from initial interoperability testing, including efficiency improvements, more robust recovery procedures for when a client lost alignment with the encryption state of the conversations and improved procedures for updating the subject and icon associated to a Group Chat.