Messaging Layer Security (MLS) is a security layer for
end-to-end encrypting messages in arbitrarily sized groups. It is maintained by the MLS working group of the
Internet Engineering Task Force to provide an efficient and practical security mechanism.[1][2][3]
Security properties
Security properties of MLS include message confidentiality, message integrity and authentication, membership authentication, asynchronicity,
forward secrecy, post-compromise security, and scalability.[4]
History
The idea was born in 2016 and first discussed in an unofficial meeting during IETF 96 in Berlin with attendees from
Wire,
Mozilla and
Cisco.[5]
Initial ideas were based on pairwise encryption for secure 1:1 and group communication. In 2017, an academic paper introducing Asynchronous Ratcheting Trees was published by the University of Oxford and Facebook setting the focus on more efficient encryption schemes.[6]
As of March 29, 2023, the IETF has approved publication of Messaging Layer Security (MLS) as a new standard.[8] It was officially published on July 19, 2023.[9][10]