Signal has started rolling out Signal Login, an optional registration method that allows users to create a Signal account without providing a phone number. The feature will be rolled out first on Android and will come to iOS later.
As we previously reported, Signal Login is not a free alternative registration method. Signal requires users who choose to register without a phone number to make a one-time payment. The price at launch is $2.99 / € 3.49, although this may vary by region and currency.
You don’t want to have to use a payment method at all… the problem with not having a phone number is there is no way to tie the account to someone who is responsible for the content, and Signal does not want the liability nor the spam traffic, of potentially harmful traffic (in whatever sense that may mean).
Or if you want the tinfoil hat response… they need/want to tie your account to a real identity for surveillance purposes, and they can’t do that if there is no phone number, so they use a payment record instead. (I made all that up and have no idea if it’s true)
They’re using zero-knowledge proofs for the payments so they can’t link the account to the credit card used to pay it.
Google can, since it’s their OS and their payments.
But even if you’re not using Play Store to pay, the vast majority of people who are paying are going to be using the same device/IP/fingerprint/etc. where Signal is running, so it’s not impossible to put the two together to link an account to a specific payment, if say, a government forced them to do so in order to track someone. It’s just a bad idea for several different privacy reasons.
Google can know you’ve paid but they can’t link it to your Signal account thanks to zero-knowledge proofs.
Except for tracing IP addresses, timing etc… as you’ve mentioned, but that’s much more involved and cannot be done retroactively.
They can… as I said they control the entire OS. They can see you’re running Signal with account# XYZ, that you clicked the pay button, that Signal generated the ZKP (which they can read in memory or network packets), and all the key clicks and numbers entered of the payment details for that ZKP, the entire process.
That’s just conspiracy theories at this point. If you assume google is constantly spying on the memory of all applications on your phone there is no reason at all to believe that.
I never said they were doing it or that people should assume it, just that it’s possible. Whether or not that matters is up to each individual’s own threat model and should be weighed accordingly.
Zero-knowledge proofs as a concept sound sus to me. How do you prove that you don’t know something? The fact of being tested already means you know of it. What’s a good writeup n how Signal does it? And how can a user of Signal test or certify it?
Here is a basic explanation for how zero-knowledge proofs can work in a very similar context as Signal.