Technology preview: Private contact discovery for Signal
I don&#x27;t really understand why this is an improvement on the existing architecture.<p>In the current contact discovery implementation you need to fully trust the server, namely the open source component that is the contact discovery service.<p>In this proposed new implementation, you still have to trust the server; you need to trust closed source processor hardware offering the Software Guard Extensions.<p>Those extensions need necessarily be kept away from user control, because otherwise you could pretend to attest a particular program, while actually running a different program. So this encourages a centralization of trust into a private key managed by processor manufacturers, which with server hardware is primarily Intel.<p>(note that you fully need to trust the processor hardware in both cases; I&#x27;m only arguing that this scheme possibly isn&#x27;t an improvement)<p>Could anyone shed some light onto why this is an improvement, assuming you don&#x27;t trust the CPU manufacturer? This is kind of the premise of the article, which notes that &quot;more fundamentally for us, we simply don’t want people to have to trust us&quot;, &quot;that’s not what privacy is about&quot;.