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by chimeracoder
1975 days ago
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> I'm just curious how we trust companies such as Signal, Telegram, Mozilla, that claim they don't store and sell our data? These are three very different companies with very different security processes and trust profiles. In the case of Signal: if you trust that the source code they distribute is the same as the app available in the Play Store, then it's pretty easy to verify that the messaging data is end-to-end encrypted in a way that prevents Signal from having much metadata that they even could store. With "sealed sender", they don't even know who's talking to whom: https://signal.org/blog/sealed-sender/ There's the possibility that Signal could ship a different app in the Play store, but that would require active malice to do in a way that would not be trivial to discover[0], and at some point you do have to trust someone. It's not impossible, but it's hard to imagine a world in which Signal is compromised but other links in the chain aren't, because quite frankly, there are far more easily corruptible or hackable links in the hardware/software stack that you use, so Signal would make a pretty inefficient target for someone who wants monetizeable data. [0] ie, an accidental divergence between the two would be more conspicuous |
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The point is that even if Signal permanently stored everything you ever sent them, then they wouldn't be able to read it.
- You can build the client yourself per Signal's reproducible builds, so actually, they could not ship a different app to the published source without it being immediately detectable
- You can validate the source code does not send any unencrypted data to Signal
- You can validate that your private keys used for encryption are stored locally on the device and not transmitted to Signal
Theoretically, anyone who has the corresponding private key could decrypt the message. So if your contact uses an unofficial client which does share their private key with a third party, then that third party could unencrypt that message, however by that point, the app creator has compromised the device anyway, and could do something as naive as take screenshots of all of the messages in the background after Signal has done the work of ensuring the secure transmission of the message.
Note, I haven't actually done all that, because I do trust Signal. But I could if I wanted to. And obviously, this assumes that all the cryptographic standards used in Signal are still unbroken - but if they were, then you're screwed either way.