Matrix also has an OTR-like multi-party encryption scheme based on the Axolotl ratchet called Olm[1]. It also went through an NCC security audit[2]. I believe it has many of the same features as (n+1)sec, so I'm a little confused why they said

> Now that a first protocol for secure distributed multiparty chat exists

are they not aware of Olm, or do they not think it provides the same guarantees?

[1]: https://git.matrix.org/git/olm/about/ [2]: https://www.nccgroup.trust/us/our-research/matrix-olm-crypto...