> 2. The bulk of metadata protection on Signal comes down to trust in SGX, which indeed is an entirely broken technology and keys can be extracted from it via a

> 2. The bulk of metadata protection on Signal comes down to trust in SGX, which indeed is an entirely broken technology and keys can be extracted from it via a number of side channels if there is sufficient motivation, such as a government trying to track down dissenting views, or a future owner of Signal that secretly is willing to cooperate with a state actor. Intel also could, if ordered, also issue a microcode update intentionally compromising the RNG used for keys, etc. Signal places a huge centralized target on its back so I think these risks are plausible and worth being aware of. Question: are you talking about address book protection, right? Because I don't wee how SGX would be required for protecting 1-to-1 chats -- keypairs for identity management and PFS-compatible encryption would suffice for that.