[CiPHPerCoder]

It looks like it uses Olm, which aspired to be an early implementation of the Signal protocol (when it was called Axolotl):

https://matrix.org/git/olm/about/

I've not audited their implementation, but at least that one design choice is sane.

IIRC there were some design changes between the early Axolotl ratchet and the Signal Protocol. If you're interested in using Olm, I would make "find out what the differences are and why" my first priority.

[NobleSir]

Ah ok I'm not necessarily so much interested in using it, but have been looking into the details of the signal ratchet recently, and was wondering what the specific changes / rationale..

[CiPHPerCoder]

If I had the time, I'd do a thorough analysis of the two and publish my findings.