Its end to end encrypted chat. They could store the encrypted messages sure. I think the biggest fear people should have with signal is the client side encryption.
Right! the keyword here is "Reproducible Builds". Basically once there is documentation about how to produce the release build, you can do it yourself and compare the resulting hash with the build distributed in the Store.
Generally speaking it does no come for free, but once you find a way (e.g. for iOS compiling with a specific Xcode version in a specific OS with some adjusted config) is kind of doable (except that Apple encrypts your build server side for DRM purposes, so you'll need a jailbroken phone to do something about it)
For Signal there is an open issue here for iOS [1]
and some documentation for Android [2]
This has nothing to do with the comment you replied to, as you have no idea what software is running on their server, so what would it even mean to reproduce it in the first place? The correct answer is merely "the server never received much in the first place so it doesn't matter as much if they stored all of it".
Ok, sure. But what do you propose? It's still a much better situation than what we have with Whatsapp. Is there something that the Signal Foundation could do to alleviate that concern you have? There's no technical solution in any technology for preventing the other side being compromised, as far as I can see.
That doesn't mean I blindly trust them, only that despite seeing potential for abuse I judge that they have more incentive to be telling the truth than not.
Also check the comment by user faitswulff where they mention how they have been subpoenaed "and could only supply account creation time and last connection time".
>>> You're still only as secure as the client on the other side of the conversation. If that one is compromised ... it could very well be sending all messages in clear text to a malicious party.
>> There's no technical solution in any technology for preventing the other side being compromised, as far as I can see.
I don't know Matrix, but I can guarantee that it doesn't solve the problem of a compromised client obtaining the messages willingly sent to it.
Yeah and since you have the possibility of dealing with state actors with deep pockets, you have to wonder if Android or iOS doesn't have the ability to copy your private keys and send those off somewhere for storage. Because of signal's popularity, it feels pretty possible to me.
If the NSA did have it backdoored somehow through the OS, it's a good bet they'd force LE agencies to use parallel construction to keep that information top secret.
That is why we really need open source hardware and OS's. A good (or even functional) open linux phone can't come fast enough.
Key authentication is not for the "paranoid" or simply those with "high risk profiles", otherwise every web browser in the universe wouldn't do it by default on every single connection to every single website. It is a normal, routine thing that is expected in all modern secure communications systems.
We've got certificate authorities to centralize trust for server public keys. And those require trusting organizations that lots of people don't want to trust. We don't have an equivalent system for individuals. There is no trivial push-button key verification process for peer-to-peer communications. Key signing parties suck and never worked. Key validation for things like Signal is nicely automated if you are physically near the other person. But beyond that it is tricky.
It is hard enough to get my parents to use a secure messenger. If I told them they needed to do a key verification process for every person they ever communicate with... they'd just go back to facebook messenger or sms.
I think it is completely reasonable for somebody to say "I don't care enough to worry about validating public keys" while also educating people like journalists about how to do that correctly.
Video calls alone won't stop a MITM attack. They would just send both video streams along, and record both sides.
Signal does have the capability to have a verification phrase displayed, which is generated from the session key. Reading that off can make the video more difficult to MITM, because then they'd have to morph the audio to match the phrase, and if it's done after the video is setup, morph the video as well. Not impossible, but difficult.
This is false. A video call will not prevent or detect MITM. You may be suggesting that a video call is used to authenticate the key, which is certainly a step in the right direction, but I don't think Signal supports this.
It will, because it will prove (or give you a lot of confidence) that the agent who sent you their public key is your legit correspondent.
This uses the fact that the client on each side is open source and inspectable, so that each side knows that they sent only the public key that they generated on their own device.
PS: to answer your last sentence, Signal allows you to flag specifically contacts that you managed to verify. Which is technically equivalent to say that you verified that the public key is theirs.
I do think it is a valid concern. Over the years, various sources reported that intelligence agencies mostly use metadata (who's talking to whom, i.e. the social network) in their analysis because message content is harder to parse and understand (and, outside of email traffic, harder to obtain in the first place).
Metadata can be as damning as the actual message data, and in a lot of places you don't want the authorities to know that you are even communicating at all.
