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End-to-end encryption based on the IETF-developed Messaging Layer Security set be used on 100s of millions of mobile devices
7 Apr 2025
Less than two years after Messaging Layer Security (MLS) was published as an RFC, it is poised to be deployed on Android phones and Apple iPhones and other devices, thanks to newly updated RCS specifications, enabling interoperable encryption between different platform providers for the first time.
The GSM Association announced that the latest RCS (Rich Communications Services) standard includes end-to-end encryption (E2EE) based on the Messaging Layer MLS protocol. RCS enhances traditional SMS messaging by offering a suite of service capabilities, including group chat, file transfers, typing notifications, and more. Key stakeholders for RCS implementation include device manufacturers, telecommunications operators, and business service providers.
MLS, developed by the IETF Messaging Layer Security Working Group, provides unsurpassed security and privacy for users of group communications applications. Using MLS, participants always know which other members of a group will receive the messages they send, and the validity of new participants joining a group is verified by all the other participants. During its development in the IETF, MLS underwent formal security analysis and industry review. It currently supports multiple ciphersuites, and makes it straightforward to add quantum attack resistant ciphersuites in the future.
The open processes and “running code” that are hallmarks of the IETF, mean that MLS is already proven to be efficient at Internet scale, working efficiently with groups that have thousands of participants. MLS is already available from, and implemented and deployed by a wide range of companies and organizations. This includes real-time platforms such as Webex, Wire, and Discord, as well as in devices such as drones.
MLS is also extensible, meaning it can be easily updated in a number of ways. Work is continuing in the MLS Working Group in a number of areas and the IETF More Instant Messaging Interoperability (mimi) working group is looking to build on MLS as they aim to specify the minimal set of mechanisms required to make Internet messaging services interoperable.