[Cryptography] Jitsi E2EE

[Dave Howe]

Had it pointed out to me that Jitsi's "beta" E2EE is apparently stable
enough that at least one webconf provider (8x8) is using it to deliver
increased privacy in their solution.

Last blog post on it was April, but they were asking for competent
cryptographic comment on the beta here:

https://jitsi.org/blog/e2ee/

anyone feel like giving them some feedback?