On: Looking back at how Signal works

[lliamander]

As I understand it, the purpose of using telephone numbers is that it can use the contact list stored on your phone without having to store contact lists on their servers.

Contact lists can be useful information for an attacker. If Signal doesn't have it, it can't be taken from them.

[em-bee → lliamander]

how does having phone numbers help with storing contacts in the client? they could store any other contact id just as well.

the only thing that phone numbers help with is discovability of signal users among your existing phone contact list.

that is something i explicitly do not want. ever.

telegram and wechat allow to block being found via phone numbers.

[Legogris → lliamander]

There's nothing inherent in phone numbers here. Both iOS and Android also allows you to add e-mail addresses (and other identifiers) to your local contacts. I'm yet to hear an argument as to why e-mail addresses or other identifiers can't be used in addition to phone numbers, or why it would be a complicating factor.