Just to echo (again), Olm is indeed an independent C/C++ implementation of the double ratchet, and we've been avoiding the overloaded term 'axolotl'. Olm has r

Just to echo (again), Olm is indeed an independent C/C++ implementation of the double ratchet, and we've been avoiding the overloaded term 'axolotl'. Olm has recently added a group ratchet on top called Megolm which diverges significantly from the Signal protocol, as it's optimised for Matrix's specific use cases of (optionally) syncing and decrypting existing history onto new devices, which obviously comes at the expense of PFS. In terms of study & scrutiny: Olm and Megolm is still alpha, we're even not using it in earnest in Matrix yet. Things are moving forward fast though, and we're getting a security audit booked in which should hopefully significantly improve our study & scrutiny quotient! (moxie: did you see my mail? any interest in grabbing a beer next week?)