Post #4612846 · Elektrine

2026-08-11 12:02 UTC

@david_chisnall@infosec.exchange > what can leak from Signal: the timestamp at which you joined the network and the timestamp at which the client last connected to the network you seem to be on a higher protocol level ignoring that Amazon servers know users' IPs (often this means location/city) out of the control of Signal, the adversary can go directly to Amazon for this info without needing collaboration of Signal, and can know then what IP/user is sending message/traffic/data to whom

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@david_chisnall@infosec.exchange 2026-08-11 14:24

@arcanechat@fosstodon.org No, absolutely not. They can go to Amazon and ask who is connecting to that service. And that's why the large anonymity set is useful because that information is sufficient only to say 'these 60M people have Signal accounts'. Good luck doing anything useful with that. If Amazon is also recording the size of messages and when they appear, that still doesn't give them much, because they're in the same place as a passive adversary and that's a problem that's in their threat model already. Messages are padded so it's hard to correlate by size (messages all will be one of a handful of sizes). Messages are buffered for some period of time, so you can see 'messages went from these IP addresses and to these IP addresses in this two-second window' but that doesn't really help you because there will be a lot of messages in that window and some of them are fake (Signal generates ghost traffic specifically to cause problems for this kind of analysis).

Open ##4612847