For those interested in ART, there is an IETF working group attempting to standardise it as the "Messaging Layer Security" protocol. Their website [1] has a draft protocol document [2] which explains the ART scheme from a concrete engineering perspective, which I find easier to follow than the original ART paper.<p>[1]: <a href="https://mlswg.github.io/" rel="nofollow">https://mlswg.github.io/</a><p>[2]: <a href="https://github.com/mlswg/mls-protocol/blob/master/draft-ietf-mls-protocol.md" rel="nofollow">https://github.com/mlswg/mls-protocol/blob/master/draft-ietf...</a>