Analysis of X's new XChat shows that X can probably decrypt users' messages, as it holds users' private keys on its servers (Matthew Green/A Few Thoughts ...)

Matthew Green / A Few Thoughts on Cryptographic Engineering:
Analysis of X's new XChat shows that X can probably decrypt users' messages, as it holds users' private keys on its servers  —  Matthew Garrett has a nice post about Twitter (uh, X)'s new end-to-end encryption messaging protocol, which is now called XChat.  The TL;DR of Matthew's post …