The scariest part of this recent news is that TM Signal seem(ed) to be interoperable. People using TM Signal could interact with actual Signal users. How are you to know whether or not your groups have people using bastardized versions of Signal? Are things like Session interoperable with Signal?
In no way does Signal prevent conversations from being archived. For all you know, a recipient could be screenshotting all of your messages, and they could even be using the official app when doing so.
If you don't trust your contacts, probably shouldn't be messaging them anything sensitive.
Yes of course. Signal can archive messages and they can be restored, you can screenshot messages and you can have them backed up as part of a policy like icloud backups.
My question is more about how do you know you're interacting with an authentic signal client, and not a bastardized one.
how do you know you’re interacting with an authentic signal client, and not a bastardized one.
I don't think that's the point... it does not matter. Even if it's an authentic client, if the device (e.g. 0 day vulnerability on the OS) or the user (e.g. does not lock their phone while going to the bathroom) is compromised, your conversation is not secure.
At the moment you can't. The only realistic way I could see that happening is if the servers would check the app's digital signature and refuse the app from communicating with the official infrastructure if it didn't match.
Signal isn't that kind of app. It protects your data in flight, but only has minimal protections after the recipient gets the message. It's a whole other game to protect data at the endpoint. If you can't trust your recipients to protect data, then you shouldn't send them data needing protection. In order to do that you need control over all levels of the device receiving the data, hardware, operating system, file system, and software. Anything else will always leave openings for data at rest at tge destination to be compromised by untrustworthy recipients.
What is the threat model where this matters? You have to trust the recipient with Signal. The only one I can think of is the case where your recipient is using a compromised fork and is unaware. In this case, talking about the tool and checking with them about what they are using is really the only countermeasure.
Well yes, anyone can compile its own version of Signal and use it and it will work as long as there aren't some major changes to its communication protocol
Some photographer took a picture of a politician in the Trump admin using a Signal clone. That signal clone allowed the user to archive chats to a third party.