[samatman]

It's not clear to me what you're actually asking for.

Signal, like it or not (I feel both ways) is keyed on phone numbers. When you look for someone, that's what you look for, and unless someone messages you first, you have to look for them.

So anyone who has your phone number and thinks "hmm, is so and so on Signal?" will find out, yes.

What's the downside to them opting in to getting alerts that the answer is now yes? I find them annoying and turn it off, but I can't avoid anyone who has my number messaging me one time on Signal, that's just how the platform works.

[BeefWellington]

> So anyone who has your phone number and thinks "hmm, is so and so on Signal?" will find out, yes.

It would be more privacy preserving to prevent that user from ever knowing the answer until I send them a message.

The usual areas this is a problem are for example: bad exes, poor former business relations, anyone who is harassing/stalking someone, and so on. I enjoy Signal as an app but it's a bit disingenuous to pretend that there aren't other ways of architecting a messenger system that could preserve anonymity better.

[zrm]

> It would be more privacy preserving to prevent that user from ever knowing the answer until I send them a message.

Someone has to send the first message. To have end to end encryption, that someone needs to be able to retrieve the other person's public key in order to be able to send it. This means they can determine whether you have a public key, i.e. whether you have the app.

> The usual areas this is a problem are for example: bad exes, poor former business relations, anyone who is harassing/stalking someone, and so on.

If your bad exes don't have your phone number, they don't learn that you installed Signal. If they do have your phone number, they learn that you installed Signal, but if them learning this one bit of information is an actual problem for you, maybe you should change your phone number.