Messaging Layer Security (MLS)


Messaging Layer Security (MLS) is an IETF working group building a modern, efficient, secure group messaging protocol.

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What is Messaging Layer Security (MLS)?

Messaging Layer Security (MLS) is a security layer for encrypting messages in groups of size two to many. It is being built by the MLS working group and designed to be efficient, practical and secure. The proposed MLS specification is in two parts:

The right place to ask any questions or keep on top of development is the mailing list, or you can check out the current documents. There’s also a public Wire group for chatting.


If you have insights, comments or just want to help, please do join in! We’re particularly interested in hearing from coders who would like to help implement draft versions, and from researchers who would like to formally analyse draft specifications, but all input is valuable. Be aware that all contributions fall under the IETF’s Note Well.


Should I use this right now?

Yes! The protocol has been approved by the IESG and has been published as RFC9420. There are several implementations, of which some are open source.