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Joined 3 years ago
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Cake day: July 2nd, 2023

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  • Yes, subpoena was poorly worded. NSL is more likely. But still it is a time-forward threat, which means there is value while the server is or was accepting sealed sender.

    And I wasn’t suggesting timing attack is required to defeat sealed sender. I was, on the contrary, pointing out that was a threat even with sealed sender. Though that is non-trivial, especially with CGNAT.

    So in summary. You’re right. Sealed sender is not a great solution. But it is a mitigation for the period where those messages are being accepted. A better solution is probably out there. I hope somebody implements it. In the meantime, for somebody who needs that level of metadata privacy, Signal isn’t the solution; maybe cwtch or briar.


  • Sure. If a state serves a subpoena to gather logs for metadata analysis, sealed sender will prevent associating senders to receivers, making this task very difficult.

    On the other hand, what it doesn’t address is if the host itself is compromised where sealed sender can be disabled allowing such analysis (not posthoc though). This is also probably sensitive to strong actors with sufficient resources via a timing attack.

    But still, as long as the server is accepting sealed sender messages the mitigation is useful.


  • Don’t mistake me for saying you’re wrong. I agree with you, mostly. But sealed sender isn’t theater, in my view. It is a best effort attempt to mitigate one potential threat. I think everybody would like that solved but actually solving it isn’t easy as I understand it. Maybe not intractable, but if you have a solution, you can implement it. That is one of the things I like about free software.

    In any case, I’m only saying Signal is good for a subset of privacy concerns. Certainly not that it is the best solution in all cases.


  • It isn’t a meme. It is a fact of modern cryptography in many settings. For example TLS, which is a huge bulk of the traffic, guarantees again privacy not anonymity. I’m not saying one shouldn’t care about metadata privacy. Every communication one engages in requires risk benefit analysis. If your threat modeling shows that for a given message, anonymity is required, then signal, and nearly every single other protocol out there is insufficient.

    That doesn’t mean TLS or lib signal, or any other cryptographic tool is not useful, especially in conjunction with other tools.

    There are many cases where I want my messages to be private and the cost of entry for the message receiver to be low. Signal is great for that. But I’m not saying no other tools should be considered, just that signal is good at what it does.



  • Cool strawmen; I didn’t say any of that. Signal protocol is awesome for privacy, not anonymity. Maybe I don’t have half a brain, but I happen to think the double ratchet implementation is an impressive piece of tech. Maybe I’m as dumb as your fever dream, but compromised exits doesn’t make tor any less of an achievement. Though i2p is also superb. I guess my brain is too weak to understand why those statements are mutually exclusive.




  • The sandboxes are different. The embeddable Java plugin sandbox was a bit different and susceptible to confused deputy and other attacks. So yeah, I guess you can say it is iterative but they’re kind of worlds apart. You can run thousands of wasm modules in a single process and have them all be completely isolated. Its performance and security gains, portability, and usability are all superb.

    I guess I can’t really defend it well, but I think it is interesting and important.