does anyone have a good summary of what data in Matrix is E2E encrypted, what isn't, and where the keys are stored? trying to put together a summary of various E2E messaging options for a local anarchist org
@joepie91 you seem like you might know about this? ^
@alive I've found this to be a decent summary: https://web.archive.org/web/20210804205638/https://serpentsec.1337.cx/matrix
(it is from 2021; I don't know how up-to-date it still is, but I don't *think* much about this has changed since)
Couple other remarks:
- Beware of claims that Signal doesn't retain metadata; these claims are popular but so far unsupported with any technical rationale or evidence, and seem to mostly boil down to "trust me bro"
- In E2EE conversations in Matrix, the server doesn't have a plaintext copy of the keys; it does have an encrypted copy if you enabled key backup (for cross-device sharing), but this only ever gets decrypted on the client
@joepie91 thanks! this is super useful!
re: signal metadata, my impression is that the protocol does enforce at least some of the metadata security (sealed sender, private groups, etc), with the caveat that some of that is "protected" by SGX — is there a good summary of what could be leaked in the case that the signal servers are malicious?