| ▲ | feurio 3 hours ago |
| And how does one verify that the public key received belongs to the intended party, rather than a mitm? If the answer is blind trust in a third party that runs the messaging service then I suspect that you can guess what the people asking those questions are really asking. |
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| ▲ | danparsonson 2 hours ago | parent | next [-] |
| https://en.wikipedia.org/wiki/Diffie%E2%80%93Hellman_key_exc... If Meta are turning it off then I guess it's reasonable to assume that there is something to turn off. |
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| ▲ | LPisGood 2 hours ago | parent | next [-] | | Diffe-Hellman-Merkel key exchange is vulnerable to attacker-in-the-middle attacks. Eave could just do key negotiation with Alice and separately do key negotiation with Bob. You have to use a slightly more complicated cryptographic protocol to avoid this issue. | |
| ▲ | tardedmeme 2 hours ago | parent | prev [-] | | How would the keys get stored in the user's private browsing window? Do they lose all chat history when they log in on a private browsing window and then close it? | | |
| ▲ | danparsonson 2 hours ago | parent [-] | | I don't know the technical details of that for sure, but I think the answer is that keys and chat history are stored on-device only; for example you lose your WhatsApp history if you don't restore a backup when moving to a new phone. If a messaging app is showing you message history in a private browsing window then perhaps the encryption key for that history is derived from your password or something like that; that can be done locally so that all the server ever sees is encrypted data. | | |
| ▲ | tardedmeme 2 hours ago | parent [-] | | If you log in to the app on one phone and then in a web browser should you still be able to see your messages in the web browser? | | |
| ▲ | danparsonson 2 hours ago | parent [-] | | Sorry do you mean, that's how it works now, or, that's how you think it should work? Are you talking about Instagram or WA or something else? edit: misread your message; if you have two sessions active at the same time, then yes I would expect both sessions to receive the same messages. | | |
| ▲ | tardedmeme an hour ago | parent [-] | | What if you log into the app and then log out of the app and then log into the app again? Should you be able to see your messages? E2EE is a fail-secure design. In case of any doubt it deletes your private messages. When applied to this case I don't think the downside of constantly losing all your messages outweighs the upside of Facebook pretending they don't have a copy of all of them. | | |
| ▲ | danparsonson an hour ago | parent [-] | | Are you asking for technical details about E2EE in messaging apps, or simply making the point that you don't like it? If you don't like it, then fine, you do you, however I would point out that we all accept some inconvenience in our lives as a trade off for improved security; the lock on my front door is inconvenient but I'd rather have it than not. As to whether or not Meta have been lying about it, then that would be on-brand for them, but then what are they turning off if so? Or maybe the whole thing is theatre, and I should better disconnect from the internet altogether? I don't see the value in speculating about that. | | |
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| ▲ | mrexcess 2 hours ago | parent | prev [-] |
| > And how does one verify that the public key received belongs to the intended party, rather than a mitm? Fingerprints. Again, this is like Crypto 101. Not saying that as a personal attack of any kind, I just remain incredulous that what used to be entry level knowledge in “our thing” has evidently become so obscure. |
