Messaging Layer Security

Security properties of MLS include message confidentiality, message integrity and authentication, membership authentication, asynchronicity, forward secrecy, post-compromise security, and scalability.{{Cite web|url=https://datatracker.ietf.org/wg/mls/about/|title=Messaging Layer Security (mls) -|website=datatracker.ietf.org|access-date=2019-03-05}}

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.{{cite web |title=Das sind die sieben Entwickler-Trends 2019: Vom Java-Comeback über MLS bis KI/ML-zentrierte Technologien |url=https://www.it-finanzmagazin.de/sieben-entwickler-trends-2019-83043/ |website=IT Finanzmagazin |date=2 January 2019 |accessdate=7 January 2019}}

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.{{Cite journal|last1=Cohn-Gordon|first1=Katriel|last2=Cremers|first2=Cas|last3=Garratt|first3=Luke|last4=Millican|first4=Jon|last5=Milner|first5=Kevin|date=2017|title=On Ends-to-Ends Encryption: Asynchronous Group Messaging with Strong Security Guarantees|journal=Cryptology ePrint Archive |url=https://eprint.iacr.org/2017/666}}

The first BoF took place in February 2018 at IETF 101 in London. The founding members are Mozilla, Facebook, Wire, Google, Twitter, University of Oxford, and INRIA.{{cite news |last1=Chirgwin |first1=Richard |title=Elders of internet hash out standards to grant encrypted message security for world+dog |url=https://www.theregister.co.uk/2018/08/22/ietf_draft_proposes_encrypted_message_security_for_all/ |accessdate=30 November 2018 |date=22 August 2018}}

As of March 29, 2023, the IETF has approved publication of Messaging Layer Security (MLS) as a new standard.{{cite web |last1=Sullivan |first1=Nick |last2=Turner |first2=Sean |date=2023-03-29 |title=Messaging Layer Security: Secure and Usable End-to-End Encryption |url=https://www.ietf.org/blog/mls-secure-and-usable-end-to-end-encryption/ |access-date=2023-07-28 |website=IETF}} It was officially published on July 19, 2023.{{Cite web |date=2023-07-19 |title=New MLS protocol provides groups better and more efficient security at Internet scale |url=https://www.ietf.org/blog/mls-protocol-published/ |access-date=2023-07-28}}{{Cite web |last1=Beurdouche |first1=Benjamin |last2=Vasquez |first2=Sarah |date=2023-07-20 |title=Messaging Layer Security is now an internet standard |url=https://blog.mozilla.org/en/mozilla/messaging-layer-security-is-now-an-internet-standard/ |access-date=2023-07-28 |website=Mozilla}} At that time, Google announced it intended to add MLS to the end to end encryption used by Google Messages over RCS.{{Cite web |title=An important step towards secure and interoperable messaging |url=https://security.googleblog.com/2023/07/an-important-step-towards-secure-and.html |access-date=2024-12-12 |website=Google Online Security Blog |language=en}} In March 2025, the GSMA announced the Universal Profile 3.0 standard of RCS would support MLS and Apple announced it would support this RCS standard on Apple Messages.{{Cite web |last=Mayo |first=Benjamin |date=2025-03-14 |title=End-to-end encrypted RCS messaging on iPhone coming in future software update |url=https://9to5mac.com/2025/03/14/end-to-end-encrypted-rcs-messaging-on-iphone/ |access-date=2025-03-14 |website=9to5Mac |language=en-US}}{{Cite web |last=Van Pelt |first=Tom |date=2025-03-14 |title=RCS Encryption: A Leap Towards Secure and Interoperable Messaging |url=https://www.gsma.com/newsroom/article/rcs-encryption-a-leap-towards-secure-and-interoperable-messaging/ |access-date=2025-03-14 |website=GSMA |language=en-GB}}

Matrix is one of the protocols declaring migration to MLS.{{Cite web |title=Are We MLS Yet? |url=https://arewemlsyet.com |access-date=2024-09-23 |website=Are We MLS Yet? |language=en-US}}

Research on adding post-quantum cryptography (PQC) to MLS is ongoing, but MLS does not currently support PQC.{{Cite web |title=Cryspen {{!}} Post-Quantum Group Messaging |url=https://cryspen.com/post/pq-mls/ |access-date=2024-12-12 |website=cryspen.com}}{{Cite web |last1=Hashimoto |first1=Keitaro |last2=Katsumata |first2=Shuichi |last3=Prest |first3=Thomas |date=2022-11-07 |title=How to Hide MetaData in MLS-Like Secure Group Messaging: Simple, Modular, and Post-Quantum |url=https://eprint.iacr.org/2022/1533.pdf |access-date=2024-12-09 |website=Cryptology ePrint Archive}}{{Cite web |last= |date=2024-02-22 |title=Post-quantum messaging: examining Apple's new PQ3 protocol |url=https://pqshield.com/post-quantum-messaging-examining-apples-new-pq3-protocol/ |access-date=2024-12-09 |website=PQShield |language=en-GB}}

{{Reflist}}

• {{IETF RFC|9420}} – The Messaging Layer Security (MLS) Protocol

Category:Cryptography

Category:Internet privacy

Category:Secure communication

{{crypto-stub}}