My concern, personally, is that Signal seems to be designing features with the assumption that SGX is sufficiently secure to be used to provide Signal's privacy

My concern, personally, is that Signal seems to be designing features with the assumption that SGX is sufficiently secure to be used to provide Signal's privacy guarantees. While yes, SGX is better than the nothing, "Intel has the keys and probably won't publish them" is very different from "only your device has the keys." To me, much of the appeal of Signal is that they actually back up their privacy guarantees with crypto, not just promise they won't read it. Given that (I assume) Intel has the remote attestation keys, SGX doesn't seem much better than any other promise-based privacy scheme. Additionally, I am generally very careful about sharing my contacts list only with apps I know won't upload it[1]. To me, silently starting to upload my contacts—even if they're protected by Actual Strong Crypto, but especially if it's a scheme like SGX that relies on humans doing the right thing—feels like a huge betrayal of trust. I'll be honest: I've never actually used Signal (I have the app installed, but nobody I want to talk to does). But I used to be enthusiastic about finding a chance to use it, but now it's more of a "probably better than any alternative" situation. [1]: It's probably silly, given that my Instagram and WhatsApp usage probably provides a better picture of my social graph than my contact list does, but oh well.