TextSecure VS ContactDiscoveryService

Moxie's reasons for disallowing Signal distribution via F-droid always rang a little flat to me ( https://github.com/signalapp/Signal-Android/issues/127 ). Lots of chatter about the supposedly superior security model of Google Play Store, and as a result fewer eyes independently building and testing the Signal code base. Everyone is entitled to their opinions, but independent and reproducible builds seem like a net positive for everyone. Always struggled to understand releasing code as open source without taking advantage of the community's willingness to build and test. Looking at it in a new light after the XZ backdoor, and Jia Tan's interactions with other FOSS folk.

Signal has documentation on how to reproduce their Play Store builds and compare them with what you've installed locally:

https://github.com/signalapp/Signal-Android/blob/main/reprod...

There's nothing on Signal blog as of yet, but Signal's git repository was tagged with v7.0.0 yesterday and we can see from the commit history since the previously tagged version (v6.74.4) that there will be a setting to hide one's phone number [1], as well as disabling the previous default behavior of advertising that one is on Signal to all their contacts already using it [2].

[1] https://github.com/signalapp/Signal-Android/commit/8797236b5... (PNP stands for "Phone Number Privacy")

[2] https://github.com/signalapp/Signal-Android/commit/6097e6c30...

Signal works the same but without the user tracking from Meta/Facebook. Many people use it as well but I'm surprised that a majority sticks to WhatsApp.

Telegram and Signal solve this.

Sadly yes: Looks like an open issue 13290 for Signal, sounds like they were/are indeed still interacting through google's push notification service, wat, and per a link at that issue it was a chore for Tutanota to break away once they realised it was a problem some years ago (though at least they thought about it years ago? wtf Signal...)

Here is one: https://github.com/signalapp/Signal-Android/tree/main/reprod...

Rule 1: Posts to r/signal must relate to Signal.

[1] https://signal.org/blog/private-contact-discovery/

Signal uses SGX for remote attestation, which presumably lets the client verify that the code running on the server is a build of the OSS code and not a modified version. But I don't know the details or if this is reliable.

SGX and remote attestation described here:

https://signal.org/blog/private-contact-discovery/

Signal does private contact discovery and the effort they've gone to to do this is quite impressive.

TEEs have numerous privacy-enhancing applications that may benefit users. One of them is, as discussed earlier, private contact discovery; the Signal application uses a contact discovery service enhanced using Intel SGX, a TEE technology, to protect its users' privacy. A similar application of TEEs is performing malware analysis in a remote cloud service, so that the service may not identify users by the contents of their devices, such as the applications they have installed, especially important as 98.93% of users may be uniquely identified by the list of applications they have installed.

Signal (or, more accurately, one of its predecessors) used to use client-side private set intersection for contact discovery, but this scales poorly [1].

Now they use a solution based on Intel SGX and server-side trusted computing [2].

[1] https://signal.org/blog/contact-discovery/

[2] https://signal.org/blog/private-contact-discovery/