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Comment by ChrisMarshallNY | Hacker News Reader

As far as privacy goes, I always say that the best way to ensure privacy, is to not take the information in the first place.

I manage an app that Serves an extremely privacy-focused demographic. I won't use push notifications or PassKeys, because each requires that the server store information that can be linked to a user. We do require a valid email account, and that's it. The email account can be a throwaway, but it needs to be able to receive email. Other than that, the user can choose to do things like mention their location (even then, we "fuzz it," at the server level), and maybe a couple of strings that can be anything they want.

Even with that, I still find that I need to constantly assuage doubts.

I know that not taking information is heresy, hereabouts, but, if I don't have it, it can't be leaked, and I can't be compelled to divulge it.

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This is the way.

Or at least it should be, if companies were putting users first (a naive thought, I know).

I have a small mobile app for recording expenses (receipts). The usual strategy would be for users to create accounts and store and sync data with my service. Potentially useful data (behavior, spending), which I don't want to touch with 10ft pole.

Instead, I keep all the data local (user's device). No registration at all. Nothing to store on the server.

Slightly more inconvenient for the users (to move to a new device, you need to export and import the local db), but cheaper and zero-stress for me.

I work at a Fortune 10 and we routinely avoid collecting PII when there’s no reason to do so. Not out of any noble championship of privacy, just because 1) legal wants less liability, and 2) subpoenas are a PITA for everyone.

That's nice, but "no reason" is often a high bar.

There's often a good reason to keep the data (marketing, product, etc), which when weighted against the potential liability, usually wins.

"often" and "usually" are doing a lot of work there.

In my experience, in my role, we often forego collection of this data because there usually isn't an obvious upside that makes it worth it. If nothing else it's a ton more privacy and security reviews.

Ditto.

What I really would love is a universal sync service that most apps would be built upon. There are apps I have used that basically say “we don’t provide storage service, but you can use your Dropbox, Google Drive, rsync service, etc.” This is really cool because while I love having my files locally I also then am entirely in charge of syncing and backing up stuff.

What do passkeys require you to store besides a public key? Isn't the whole idea that passkeys don't burden providers with sensitive credentials?

A public key can be associated with an individual user. Same with the pseudo-UDIDs, that are required for push notifications.

I guess I don't see a practical way of exploiting that association. UDID, that's unique identifying info for sure. But a public key that's never reused?

It can still be associated with a user, the same goes for push notification IDs.

It would be difficult, but AI has suddenly made difficult things a lot easier.

But so can the email address.

To an extent. They can still use a throwaway or redirect address.

With PassKeys and push notifications, there’s no way to do that.

You can use KeePassXC for passkeys. It will generate completely unidentifiable public keys, and save the the private keys to a portable KDBX file.

It's unfortunate that passkeys have been such a disaster. Attestation should never have been part of the spec, it should never have been presented as a replacement for hardware U2F keys, and a private key file format should have been defined on day 1. But there is useful functionality buried under all the noise and confusion.

You can throw away a passkey just as well as you can throw away an email address.

This is a good point. I'm not sure that it is as obvious to nontechnical users, though.

I suspect that many people's Passwords apps are littered with dead passkeys.

I'd say it's way more obvious than using a 3rd party email service.

And that's another thing: if you use a 3rd party e-mail service then you have to trust a 3rd party not to abuse that. If they have control of that email address they can take over your account. If it's a temporary address, who's to say when that address gets reused?

If you don't use a 3rd party service then you have to have your own domain for that e-mail address, that domain name can then also be traced back to you.

If you want it to be anonymous, you shouldn't use e-mail at all and only allow passkeys.

This is all stuff that we'll need to consider. We have to have a valid email address, because the app won't work, otherwise. That's really the only requirement for server-stored information. There's a bit of stuff that stays on the phone. We try to use the Secure Enclave, as much as possible.

The issue is that the demographic we Serve (recovering drug addicts) is a very privacy-sensitive one. Another demographic (that we don't serve) is non-hetero/cisgen folks. Both of these demographics can mean persecution, and even death, in some places, so we are not casual at all about the privacy of our end-users.

At the same time, too much security can render the app useless, so we need to find a balance. The issue with information, is that once it's out; it's not so easy to put back in the bottle, so we tread carefully.

If they're so privacy-focused, can't they generate a key specific to the app?

That’s pretty much what Apple does with both the PassKey and push notifications.

The PassKey is a bit better, because there’s no need to go through a broker server, like you do with push notifications, but the key is still connected with an individual user and device, so an association can still be established, with some difficulty.

If you don’t have the key or the ID stored on a server, then even that is not an issue.

I built a micro-journaling app back in the day and subscribed to this philosophy as much as i could have. On Android, i even didnt let the app have the permission to access the internet. Everything was stored on device, encrypted. However i was still scared that individual phones would be hacked (or the app itself) and the info would get out anyways.

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