Greetings!

A friend of mine wants to be more secure and private in light of recent events in the USA.

They originally told me they were going to use telegram, in which I explained how Telegram is considered compromised, and Signal is far more secure to use.

But they want more detailed explanations then what I provided verbally. Please help me explain things better to them! ✨

I am going to forward this thread to them, so they can see all your responses! And if you can, please cite!

Thank you! ✨

  • Arthur Besse@lemmy.ml
    1·
    15 hours ago

    They have to know who the message needs to go to, granted. But they don’t have to know who the message comes from, hence why the sealed sender technique works. The recipient verifies the message via the keys that are exchanged if they have been communicating with that correspondent before or else it is a new message request.

    So I don’t see how they can build social graphs if they don’t know who the sender if all messages are, they can only plot recipients which is not enough.

    1. You need to identify yourself to receive your messages, and you send and receive messages from the same IP address, and there are typically not many if any other Signal users sharing the same IP address. So, the cryptography of “sealed sender” is just for show - the metadata privacy remains dependent on them keeping their promise not to correlate your receiving identity with the identities of the people you’re sending to. If you assume that they’ll keep that promise, then the sealed sender cryptography provides no benefit; if they don’t keep the promise, sealed sender doesn’t really help. They outsource the keeping of their promises to Amazon, btw (a major intelligence contractor).

    2. Just in case sealed sender was actually making it inconvenient for the server to know who is talking to who… Signal silently falls back to “unsealed sender” messages if server returns 401 when trying to send “sealed sender” messages, which the server actually does sometimes. As the current lead dev of Signal-for-Android explains: “Sealed sender is not a guarantee, but rather a best-effort sort of thing” so “I don’t think notifying the user of a unsealed send fallback is necessary”.

    Given the above, don’t you think the fact that they’ve actually gone to the trouble of building sealed sender at all, which causes many people to espouse the belief you just did (that their cryptographic design renders them incapable of learning the social graph, not to mention learning which edges in the graph are most active, and when) puts them rather squarely in doth protest too much territory? 🤔