I feel like there's a bubble of people for whom phone numbers are perhaps a useful, durable identity token, but I really think it's very much a bubble. Most people's phone numbers change fairly frequently.
Citation?
I think it’s just as easy to claim (and I certainly would bet that) most people’s phone numbers do not change frequently - I’d wager on something like 70% remain the same for 5+ years.
Curious / interested to be proven wrong though?
A previous purchaser of a newly provisioned phone number may have already deleted their Signal account before releasing it.
https://support.signal.org/hc/en-us/articles/360007061192-De...
Very few people change their phone number ever.
My servers also don't keep any record of conversations or "buddy lists". Yes, contact lists get wiped when changing device and email addresses aren't as easily stored in phone books (I don't even access a user's phone book for that matter). Just saying that it's possible to not use phone numbers. Granted not as convenient once you've built your entire user base off of their phone numbers
Email is more private though
> By contrast, other relatively popular messengers essentially keep a plaintext database of who talks to who on their service.
I know, there are plenty of not-so-privacy-preserving messengers out there. The way Ricochet[1] and Briar[2] does it is probably the most privacy-preserving one, and it can be made extremely convenient.
[1] https://github.com/blueprint-freespeech/ricochet-refresh/blo...
how do people again discover each other on Signal most of the time?
Anyways, nothing prevents Signal form creating it's own contact list within the app, perhaps bootstrapped from the existing one
This issue has been rehashed dozens of times on HN before (use the search bar below) and has basically nothing to do with the article.
I find it funny rather than scary because I knew the tradeoffs Signal decided on even before I started using it. The fact that you use Signal itself is not a secret. If you need that to be secret, use a burner phone or something else. But I'm pretty sure not everyone else knew that when they joined.
In one case, I got notification that a guy I knew in high school had joined Signal, he was pretty far left then, and googling him I found out he was extremely far left now (splinter of a splinter of an anti-electoral Maoist group). I sent him a friendly note welcoming him, and explaining the basic thing I've explained here, that everyone can see you joining signal.
I never got a reply.
> The first instinct is often just to hash the contact information before sending it to the server. If the server has the SHA256 hash of every registered user, it can just check to see if those match any of the SHA256 hashes of contacts transmitted by a client.
> Unfortunately, this doesn’t work because the “preimage space” (the set of all possible hash inputs) is small enough to easily calculate a map of all possible hash inputs to hash outputs. There are only roughly 10^10 phone numbers, and while the set of all possible email addresses is less finite, it’s still not terribly great. Inverting these hashes is basically a straightforward dictionary attack. It’s not possible to “salt” the hashes, either (they always have to match), which makes building rainbow tables possible.
Regardless of this, Ricochet and Briar both use Tor hidden services and they are metadata-free. You do not send any metadata to any servers. I have a link to the design of Ricochet that is easily digestible in some of my other comments.
What phone numbers allow Signal to do is to piggyback off the contact lists people already have on their devices.