Quite a bit of code related to usernames has already been checked into Signal. Here's the username regexp and the method that checks if a username is valid: https://github.com/signalapp/Signal-Android/blob/a5e5a735800...

A Signal username is global to Signal communication; a phone number is global to far more.

Scope tends to widen.

It was trivial to create multiple pseudonyms and the only one who could unmask it was Google and whoever could force Google.

This of course meant you had to trust Google but compared to having to trust everyone that is still a huge improvement.

The other problem is actually the act of sharing a username. If my username is "godelski" then yeah, I can share it on HN and Reddit where I use that username. But now I've deanonymized myself to friends and family who can see that username through Signal. Alternatively, if I have a username "not_godelski" then how do I get in contact with someone on HN while maintaining anonymity? If I use share it under this account then those two names are linked forever and that deanonymizes me. I can't create a new account just to share that name because those groups know me by that name. If I can have an infinite number of usernames, that solves the problem, but this isn't practical (even 5 usernames would be problematic and requires a lot of cognitive load, which is antithetical to Signal's philosophy).

There's also a third problem I don't care as much about but I'd assume Signal does. And that's naming collisions. NYT has a Signal number that allows whistleblowers to contact them. What's stopping me from creating the username NYT_Whistleblower and becoming a honeypot?

Edit: Lots of people are saying you can't share contact without revealing your identity. Does a 1-click link not solve this issue? If I post a signal.me/#one-time-code/jdjkerfe2r3rfwseffre5ge5g then I don't see how that would reveal my identity. (I'm also not a fan of "you can't". I can understand this being unsolved, but it feels like there are solutions to this problem)

You can't, and I don't think that's a surprising outcome. If you have a non-anonymous identity on one platform, and link it to your anonymous identity on another, then that latter identity is no longer anonymous.

You just can't really mix your anonymous and non-anonymous worlds without de-anonymizing the latter. That's kinda a fundamental property of how anonymity works, isn't it?

On the far anonymous end you've got 4Chan style anonymity, no permanent or any ID at all. Keeping track of individual people is nearly impossible. Conversations are chaotic and hard to follow. Pretty solid privacy.

I guess the next step up would be per conversation/thread/group whatever ID, you trade a small amount of privacy for improved conversation, privacy is still pretty good, a poor choice in username or username reuse could prove to be privacy risks.

I guess next up from that would be something like forum style usernames, like hn or reddit where it's persistent across the entire platform, but still doesn't have to be linked to anything permanent or 'real'. It increases the privacy risk again because now, your conversation history can be tracked across time. This does make it easier for more permanent connections to be made between users but does make it easier for sensitive details to be leaked depending on the user's behaviour.

Up from there you start getting into IDs that are linked to real world information about a user. This provides some pretty obvious privacy risks.

Ids linked to phone numbers are a strange case of trying to take an ephemeral ID that in todays world can change quite regularly and use it as a source of info for an ID based on real world information.

Connecting consists of exchanging public keys (which can be global per person, or compartmentalized per contact/conversation).

Rather than a central server relating messages to the right peers, there’s a global feed where you attempt to decrypt everything and the ones which succeed are obviously addressed at you.

The benefit here is that not even a central server operator like Signal can trivially tie messages or chat identities to peers.

That's easy; you want an internal identifier for Signal accounts that is unrelated to display name. This is already routine in most places including Discord.[1] Nothing stops you from creating the username NYT_Whistleblower, but that won't be what the NYT advertises to potential whistleblowers.

> Alternatively, if I have a username "not_godelski" then how do I get in contact with someone on HN while maintaining anonymity?

Well, you can't. Revealing your identity necessarily involves losing your anonymity, and I don't understand how you think those two actions could be theoretically separated. If you want to share your Signal identity with someone who only knows you as "godelski from HN", then once the sharing is accomplished they will know that "godelski from HN" and "godelski from HN's Signal username" are the same person. So will anyone who was allowed to watch the sharing.

Perhaps what you want is a single buffer account, where you tell people on HN to contact your buffer account (openly identifying it with yourself), and then you use the buffer account to reveal the identity of your actual account?

[1] Note that there is a tension between having a unique identifier by which Signal knows who you are, and the need for participants in two group chats not to be able to notice that your two usernames in those two chats belong to the same person. Discord is failing at this. To be part of a group chat at all, someone is going to have to have an identifier for you; if you want to maintain cross-chat anonymity, you'll need to be able to generate disposable identifiers that you can give to chat admins.

Suppose Signal generates a one-click (or even temporary) link. I can share that link that'll connect. That can accomplish the same thing as a signal.me address. Onetime links are definitely a thing. I'm sure people that know more can share even more creative ways to accomplish this. Someone has to have some fancy ZKP method for initiating contact.

> Perhaps what you want is a single buffer account

I think I covered this in my "infinite accounts" above.

> [1]

Seems to be more easily solved by letting me specify a handle at the per-chat level.

> Nothing stops you from creating the username NYT_Whistleblower, but that won't be what the NYT advertises to potential whistleblowers.

Seems you're passing the buck. Making it a "not my problem" issue and I think this is a big enough problem that it would make platforms like NYT wary of using such a system.

How? So you've got your account with a display name of "NYT_Whistleblower". Now... how does somebody else find it by accident?

1. Godelski shares 1-click link with Brigandish.

2. Brigandish clicks link and that registers Brigandish's Signal account with Godelski's Signal account, but no communication can take place yet.

3. Brigandish shares 1-click link with Godelski.

4. Godelski clicks the link, if Godelski has a registration waiting for Brigandish's Signal account then the handshake is complete.

I came up with this right now, I'm sure someone else can find a problem with it beyond it being a tad more bothersome than usual.

Well, if you're under attack, the 1-click link will reveal your identity to the first person to click on the link. But that's entirely different from what you're asking for, which is to reveal your identity to a specific person designated by yourself, regardless of who sees your link first.

The reason people are telling you you can't reveal your identity while staying anonymous is that those are opposite concepts. But if you're not trying to preserve your anonymity against the same person you want to reveal your identity to, you're on the much simpler problem of communicating in a way that is resistant to eavesdroppers. You don't need anything from Signal; you need an encrypted channel of communication with your counterparty.

That's true, but much easier to defend against. Since you can talk in a semi-synchronous manner and we can have a high _probability_ that the correct person will be be the one clicking on the link.

So if it works:

Godelski: Hey, let's chat on Signal, my link is signal.me/#one-time-code/jdjkerfe2r3rfwseffre5ge5g

Thaumasiotes: Great!

If it doesn't work:

Godelski: Hey, let's chat on Signal, my link is signal.me/#one-time-code/jdjkerfe2r3rfwseffre5ge5g

Thaumasiotes: Hey, link seems bad

While you're right that there are no guarantees, I don't think that's true for any system. There's only probabilities. Obviously there are other ways to do this along the same lines. I can have a global link that has infinite links (e.g. one I could place under my HN profile) that I can only have there. These strings are much easier to generate than usernames given that with higher entropy you don't have the same likelihood of a birthday clash.

I'm not saying that communicating without revealing your identity isn't a challenging problem. But there are clearly some versions that reveal _more_ than others. Maybe there's no perfect system (I'm not smart enough to know) but there's clearly better ones than others. Standard usernames seems to just be throwing your hands up and giving up.

> you're on the much simpler problem of communicating in a way that is resistant to eavesdroppers

We already have that. It's called E2EE.

> Godelski: Hey, let's chat on Signal, my link is signal.me/#one-time-code/jdjkerfe2r3rfwseffre5ge5g

> Thaumasiotes: Hey, link seems bad

Sure, that interaction degraded gracefully. But your identity was also permanently compromised; it doesn't make sense to focus on how easy it was for me to say "hey, that didn't work". The reason the link went bad is that you disclosed your identity to someone you were specifically trying to keep it a secret from. This is an unforgivable flaw in the protocol.

>> you're on the much simpler problem of communicating in a way that is resistant to eavesdroppers

> We already have that. It's called E2EE.

Well, no. E2EE is the answer to resisting one particular eavesdropper. What you're trying to get at is called "public key cryptography", the system whereby two strangers can establish a secure channel without relying on an already-existing secure channel. E2EE has nothing to say about establishing secure channels; it just refers to the concept of using one.

Here's the system you actually want:

Godelski: Hey, let's chat on Signal, what's your PGP public key?.

Thaumasiotes: My PGP key is yyyyy.

Godelski: [encrypted for yyyyy: Here's how you can find me on Signal]

But notice that Signal doesn't participate in this exchange. Nor can it. I'm not on Signal, as far as you know; your messages to me have to use some other medium.

Only if I accepted the request. Clicking the link would presumably act the same way as a contact that you don't know. It asks before you accept. So I can wait till you respond.

Users in conversations are linked by (private id and the persona id at creation), where messages get sent between the clients.

Meanwhile, people (or rather private ids) get added to conversations by using the publicly searchable personas (i.e. any globally unique string). Then for the life of that conversation, the persona is sticky. You could even add multiple personas from the same user to the same conversation if that is necessary. For some the persona id could be phone numbers, full names, online aliases, emails, etc.

People can then hand out different personas depending on the context.

I can see some reasoning, but there's technically nothing stopping them from allowing more universal ASCII characters at the very least.

Session has a lot of cool things going for it. They managed to solve the problems of P2P (high battery life number one) with these incentivised traffic passing nodes. They improved on TOR and you can already use the fruits of its invention for general traffic.

The big problem as I see it is the team is all Australian. They'll need to find a way to pass stewardship to the community in time.

Because that's a pipe dream.

First of all, you can't monetize it, and, unfortunately that is a non-starter. I can't see people throwing money at this, with the implications. Secondly, assume I want to contact the same anonymous person again. They have to somehow easily prove they have access to that username.

Even 4chan had a mechanism for this. Assuming you don't shield your IP, or you move between locations between, at least the service knows that, and that isn't anonymous.

A pre shared key off a one time pad only proves that someone has the same pad.

I think anonymity isn't achievable. Secure is more important. I talk to someone a lot, I want that secure. I don't really care if anyone knows we're talking, just whether they know the content.

Hosting your own metal somewhere helps with that. You'd obviously notice a warrant or whatever.

> Even if you create a throwaway email account somewhere, it'll often be traceable back to you somehow.

I'm surprised to hear you say this considering your completely opposite stance in response to a comment of mine. I don't see how a throwaway email is any less anonymous than a username. In fact, I see it as more anonymous since I can generate these on the fly whereas I can't do this with usernames.

i'm really glad that they're moving away from phone number as identity, and hopefully to fully anonymous, which they've rightly been criticized about up until this announcement.