Comment by saguntum
13 hours ago
I haven't tried it, but Signal supports not sharing your phone number/just communicating with usernames: https://signal.org/blog/phone-number-privacy-usernames/
You still need to use your phone number to sign up, though.
> You still need to use your phone number to sign up, though.
Which defeats the whole point. What if the FBI politely asks Signal about a phone number?
All they'd learn that way is that that phone number has a Signal account, when it was registered, and when it was last active. In other words, it doesn't tell them whether it's part of a given Signal group. (See https://signal.org/bigbrother/.)
They publicly publish these requests. You can see how little information is provided — just a phone number and two unix timestamps IIRC. https://signal.org/bigbrother/
I might be misremembering or mixing memories but i remember something about them only storing the hash of the number.
So the FBI cant ask what phone number is tied to an account, but if a specific phone number was tied to the specific account? (As in, Signal gets the number, runs it through their hash algorythm and compares that hash to the saved one)
But my memory is very very bad, so like i said, i might be wrong
It would be absolutely trivial for the FBI to hash every single assigned phone number and check which one matches. Hashing only provides any anonymity if the source domain is too large to be enumerable.
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