Technology preview: Private contact discovery for Signal
1–10 of 169 posts
Re: Technology preview: Private contact discovery for Signal
#2As always, Moxie impresses. :)
Re: Technology preview: Private contact discovery for Signal
#3>clients will be able to efficiently and scalably determine whether the contacts in their address book are Signal users without revealing the contacts in their address book to the Signal service.
This should be the fucking defacto standard!
We really need Privacy-as-a-service and security-as-a-service
Re: Technology preview: Private contact discovery for Signal
#4This is totally awesome technology, and it sounds like it is well designed and scalable. AWESOME.
Re: Technology preview: Private contact discovery for Signal
#5The security assumptions that SGX is built on are flawed. They assume that no side channel attacks will be mounted to determine the processes that occur in side the chip. You can even build software to do side channel analysis on the physical chip:
7:16:26 Daniel Gruss / Michael Schwarz - Cache Attacks on SGX https://youtu.be/eCE2OzKIab8?t=26193
Re: Technology preview: Private contact discovery for Signal
#6So this looks better than the status quo, but is it really trustless? Couldn't OWS still be compelled to drop something in that walks & talks like this secure enclave, but enables remote collection of address books? It seems we've just moved the trust down the stack into hardware.
Kinda depressed that we seem to have given up on the scalable Private Set Intersection problem. It's a hard problem but an important one for privacy-preserving social apps.
Re: Technology preview: Private contact discovery for Signal
#7> clients will be able to efficiently and scalably determine whether the contacts in their address book are Signal users without revealing the contacts in their address book to the Signal service. This should be the fucking defacto standard! We really need Privacy-as-a-service and security-as-a-service
> We really need Privacy-as-a-service and security-as-a-service
We can provide food-as-a-service, but we can't provide digestion-as-a-service. Which is to say, we can provide many useful services but privacy and security are things that can't be outsourced, just like you can't hire someone to digest your food for you. They require deep integration and planning, and they're difficult to pull off in the best of cases. Trying to service-ify them is just asking for pain.
Re: Technology preview: Private contact discovery for Signal
#8Can I use Signal on iOS without obligatory access to Contacts already?
Re: Technology preview: Private contact discovery for Signal
#9Super interesting.
A related problem I think about frequently is this: how do users know/trust the client software they are running works as they expect?
I wonder if there is some way to use SGX to enhance trust in the client side too.
Re: Technology preview: Private contact discovery for Signal
#10Signal is applying SGX secure enclaves to engineer a new contact discovery server design. This is doubtlessly promising and innovative.
My only question is the following: what protection is there against the server sending a correct remote attestation for the code being executed to the client, and then, right after this attestation is validated, the server rerouting the network pipe so that the contact list the client sends goes to a different server running different, non-SGX code?
I ask that as a non-expert in SGX, so this might be something that has an obvious answer.
Edited to add: Also, isn't it the case that verifying SGX remote attestations requires phoning home to Intel? If that's the case here (and I'm not sure that it is,) is Intel consequently able to build an IP address graph of Signal users?
Edit 2: Matthew Green has provided a credible answer to my initial question: https://twitter.com/matthew_d_green/status/91274558241391820...