I remember a time when visiting a website that opens a javacript dialog box asking for your name so the message “hi <name entered>” could be displayed was baulked at.
Why does signal want a phone number to register? Is there a better alternative?
I remember a time when visiting a website that opens a javacript dialog box asking for your name so the message “hi <name entered>” could be displayed was baulked at.
Why does signal want a phone number to register? Is there a better alternative?
So, you’re going to get two schools of thought on this, and one of them is wrong. Horrendously wrong. For perspective, I was a certified CEHv7, so take that for what its worth.
There’s a saying in security circles “security through obscurity isn’t security,” which is a saying from the 1850s and people continually attempt to apply the logic to today’s standards and it’s–frankly stupid–but just plain silly. It generally means that if you hide the key to your house under the floor mat, there’s no point to having the lock, because it doesn’t lend you any real security and that if you release the schematics to security protocols and/or devices (like locks), it makes them less secure. And in this specific context, it makes sense and is an accurate statement. Lots of people will make the argument that F/OSS is more secure because it’s openly available and many will make the argument that it’s less secure. But each argument is moot because it deals with software development and not your private data. lol.
When you apply the same logic to technology and private data it breaks down tremendously. This is the information age. With a persons phone number I can very likely find their home address or their general location. Registered cell phones will forever carry with them the city in which they were activated. So if I have your phone number, and know your name is John Smith, I can look up your number and see where it was activated. It’ll tell me “Dallas, Texas” and now I’m not just looking for John Smith, I’m looking for John Smith in Dallas, Texas. With successive breakdowns like this I will eventually find your home address or at the very least your neighborhood.
The supposition made by Signal (and anyone who defends this model) is that generally anyone with your private number is supposed to have it and even if they do, there’s not much they can do with it. But that’s so incredibly wrong it’s not even funny in 2025.
I’ve seen a great number of people in this thread post things like “privacy isn’t anonymity and anonymity isn’t security,” which frankly I find gobstopping hilarious from a community that will break their neck to suggest everyone run VPNs to protect their online identity as a way to protect yourself from fingerprinting and ad tracking.
It frankly amazes me. Protecting your data, including your phone number is the same as protecting your home address and your private data through redirection from a VPN. I don’t think many in this community would argue against using a VPN. But why they feel you should shotgun your phone number all over the internet is fucking stupid, IMO, or that you should only use a secure messaging protocol to speak to people you know, and not people you don’t know. It’s all just so…stupid.
They’ll then continue to say that you should only use Signal to talk to people you know because “that’s what its for!” as if protecting yourself via encryption from compete fucking strangers has no value all of a sudden. lol
You have to be very careful in this community because there are a significant number of armchair experts which simply parrot the things that they’ve read from others ad-nauseam without actually thinking about the basis of what they’re saying.
OK. That’s my rant. I’m ready for your downvote.
The only thing I’ll tack onto this is that with the introduction of Signal usernames, you still have to give Signal your number to verify that at least on some level, you probably are a real person. As someone with 5 different phone numbers, probably doesn’t stop spam as much as they’d hoped, but more than they feared, but at least now you don’t have to give that Craigslist guy who uses Signal your phone number, just your username. Is that the best method? I dunno, but but it is something.
I was unaware of this change, and it’s perfectly acceptable. No one has any ground to lambast Signal for requiring phone numbers to get an account. I think that’s a perfectly reasonable spam mitigation technique. The issue is having to shotgun your phone number to every Howard and Susan that you want to use Signal to communicate with.
This was honestly the only thing holding me back from actually using Signal. I’ll likely register for an account now.
If you are even remotely involved in any activist type of things, you certainly don’t want this US government honeypot have your phone-number and device id.
At least in theory, this is mitigated. The signal activation server sees your phone number, yes. If you use Signal, the threat model doesn’t protect you from someone with privileged network or server access learning that you use Signal (just like someone with privileged network access can learn you use tor, or a vpn, etc).
But the signal servers do not get to see the content of your group messages, nor the metadata about your groups and contacts. Sealed sender keeps that private: https://signal.org/blog/sealed-sender/
You would obviously want to join those groups with a user Id rather than your phone number, or a malicious member could out you. It’s not the best truly anonymous chat platform, but protection from your specific threat model is thought through.
edit: be sure to go to Settings > Privacy > Phone Number. By default anyone who already has your phone number can see you use signal (used for contact discovery, this makes sense to me for all typical uses of Signal), and in a separate setting, contacts and groups can see your phone number. You will absolutely want to un-check that one if you follow my suggestion above.
There are some mitigations in place, yes, but Sealed Sender on a centralized platform is snake-oil as someone with server access can easily do a timing attack and discover who communicated with whom.
Spam accounts are clearly the biggest factor for not letting anyone just sign up with an email. Although getting a new email without a phone verification is getting increasingly hard now.