[danShumway]

> Also consider that Apple zeroes out attestation for its devices

This may be the saving grace because it may end up being that whether or not attestation is part of the standard doesn't matter because companies won't be able to use it. But it doesn't mean that attestation is harmless, it means that we're very lucky that (for now) Apple is deciding to effectively make it impossible for a commercial service to actually use it reliably.

> It prevents you from using security keys that aren't configured for user verification, and they don't do that through attestation.

Fair point, I don't know that this is actually using attestation and that it's not just the Yubikey reporting back that it doesn't support that field. I do quibble somewhat with "they're not blocking Yubikeys, they're just blocking <description of a Yubikey>." But... yeah, I'll grant you're probably right that this is not using attestation.

> I don't see a world where you can export passkeys from Apple iCloud Keychain and import them into Google Password Manager.

That's exactly what I mean when I say it wouldn't be sufficient. When I talk about syncing, I'm talking about transferring into and out of ecosystems, not just specific devices. What you're describing is a system where I can use the KeePassXC ecosystem to use keys across multiple devices. But I can't transfer those keys out of the KeePassXC ecosystem (unless hopefully other vendors like 1Password add support), and if someone starts using iCloud, they're stuck with same vendor lock-in.

This is effectively saying, "you'll have a closed ecosystem for most people, but people who know enough beforehand to avoid it can somewhat avoid it." We should expect better from a standards body that purports to be building an Open standard.

I really don't see how this is an out-of-scope problem for the FIDO Alliance. They have input from every single major OS. All of the players are in the same space. And their entire job is to dictate how this is going to work. I'm just asking them to do that job. A spec for portability is not that big of an ask compared to everything else they're already working on as part of this.

It's not really that different than a spec for logging in using a standardized QR code, or over Bluetooth -- all of which was considered in-scope for them to to work on. Portability is just part of the general interoperability work that we should be expecting them to do.

> Do you want your browser deciding for you what websites you can log in to?

Of course not; in very typical fashion Google's solution to the problem may be worse than the problem itself. Google is very fond of recognizing that a feature is abusable and saying, "well, how about we prevent that abuse by giving ourselves even more capricious power?"

But I do think it shows I'm not being paranoid, that this is a legitimate worry that even Google recognizes is worth worrying about. Google is part of the FIDO Alliance and it's not looking at attestation as a theoretical risk; it's looking at it as a very plausible risk that it needs to have policies around.

Which I think is pretty reasonable given that every single instance of attestation in the past has been used for DRM, and there's nothing special about attestation in this spec that would stop that from happening. I really do think the burden of proof here is on you to describe why you think Netflix/Banks/etc... are suddenly going to act differently now than they have with every other attestation method they've had access to leading up to now.

The only answer I can think of is, "they'll act differently because Apple is effectively killing attestation for platform keys for everyone." But that's not really a defense of attestation, it's just something to thank Apple for.

[sebk]

let me restate, they're not "blocking the description of a Yubikey" either. You can register one, and in fact I just did to try it out. The Yubikey needs to be configured with a PIN which you do through Yubikey manager. They're blocking authenticators that don't have additional protection other than just presence.

> That's exactly what I mean when I say it wouldn't be sufficient

I think we're confusing what the role of a standard is, versus what other features can be built around a standard capability. With an open fabric, vendors like KeePassXC can allow exports in formats that can then be imported by other sync fabrics as I described previously. The standard mandating it would be a good reason for vendors not to adopt the standard, or adopt a crippled version. Given the fact that WebAuthn ties capabilites to the authenticator at registration time I think it's understandable that vendors like Apple want give RPs assurance that keys are entirely contained in an ecosystem that guarantees those assertions. You will have options, including not using Apple/Microsoft/Google's sync fabrics, and to move off these sync fabrics if you consider them insufficient, but not by exporting keys directly.

> I really don't see how this is an out-of-scope problem for the FIDO Alliance (...) It's not really that different than a spec for logging in using a standardized QR code

Logging in using a QR code or BLE is part of the hybrid transport in CTAP, which deals with how authenticators communicate with clients. It's very much within FIDO. Establishing trust between devices in different ecosystems to form a circle of trust so that key material can be shared doesn't really have anything to do with logging in to services, so it's not WebAuthn. It also doesn't deal with client to authenticator communication as there's no client. If anything, a standard like TPM (ISO/IEC 11889) is a better fit, but probably too low level for that exact use case.

> Which I think is pretty reasonable given that every single instance of attestation in the past has been used for DRM

Going back to attestation, I don't think that in general it's in the best interest of services to not allow you to log in to them, but I can see a bank in their typical backwards-fashion issuing some branded keys and only letting you use those (Symantec, I'm looking at you). The reality is that standard or not, if RPs want this functionality, it'll be there. Standards simply attempt to provide the bare minimum for interoperability that every party can agree to. The alternative is not an attestation-free world. It's a bank asking you to log in with a flawed key they purchased from an ancient vendor because there's no standard offering that does what they want. I'd much rather have a Bank of America branded Yubikey with enterprise attestation using WebAuthn than some weak and poorly implemented proprietary token like the ones they issue today.

[danShumway]

> They're blocking authenticators that don't have additional protection other than just presence.

I know this isn't strictly attestation, but this is blocking authentication based on attributes of the device, correct? I'm sort of quibbling over details here I know, but this is basically saying "we are checking for a pin protection or biometric protection and limiting how an authenticator is used based on the presence of that feature."

> You will have options, including not using Apple/Microsoft/Google's sync fabrics, and to move off these sync fabrics if you consider them insufficient, but not by exporting keys directly.

And that is a good reason to reject the standard as harmful.

I'd love to use keys for log-in, it would be a huge boost to security. But if portability between sync fabrics as you call them isn't supported, then we can stick with passwords. I'm fine with that, and I think other people are as well. Ultimately, passkeys have to be better than what we have, and out of luck or history or whatever reason password vaults are extremely portable between different ecosystems. Even ecosystems that try to lock down passwords struggle to do so, because ultimately passwords are text and in the worst case they can be copied and pasted between managers. So if passkeys aren't similarly portable and they become another tool for holding people down into a single OS ecosystem (even if there are options that allow avoiding that), then they're harmful -- the security gains are not worth the downside.

It does not address my concerns to say that a user who knows about the dangers of vendor lock-in in advance can avoid it in some situations.

> Establishing trust between devices in different ecosystems to form a circle of trust so that key material can be shared doesn't really have anything to do with logging in to services

It absolutely does, it dictates how that login information gets shared between devices. As far as I'm concerned it's just another part of transport.

It's also relevant to FIDO in the sense that it is a major barrier of entry to getting passkeys to be accepted by the general public. At the end of the day, the highest-level responsibility for FIDO is to figure out a standard that's usable. The lack of portability keeps the standard from being usable. It is the single biggest complaint that people have about passkeys.

Yes, that is a problem they should solve, particularly because everyone who would be required to be in the same room to solve that problem is currently in the same room, and all of them have a vested interest in getting rid of barriers to passkey adoption.

Ultimately, does FIDO want this to be adopted by normal people or not? If the answer is yes, then portability is a problem they need to tackle. Again, every single company required to tackle this problem is currently a member of that alliance.

> Standards simply attempt to provide the bare minimum for interoperability that every party can agree to.

That bare minimum of interoperability should not exist for abusive uses of the technology. Like you said, there are solutions for this today. Companies that are abusing their customers should not get extra support from OSes and standard bodies to help them do it.

Bank of America can already use a Yubikey today. Or they can use a poorly implemented proprietary token. And maybe if that goes badly for them, they'll use an actually more secure option instead of LARPing security.

But look, this is exactly what people said about web video DRM, it's exactly what people say every time these conversations around DRM and fingerprinting come up. Companies are going to fingerprint your device anyway, we might as well give them a device ID for advertising. Companies are going to build weird browser extensions, we might as well get rid of them and make DRM part of the spec. It's really just an excuse, the standards make it easier to do this stuff. They're pursued because they get rid of the inconvenient parts of abusing users. And in doing so, they remove a barrier of entry that should exist.

And integrating this into web browsers on desktop platforms is a huge gift to companies that want to do this. I already can't use my bank's app on a deGoogled phone but at least I can sign in on a web browser, because in the world that currently exists attestation through a general web browser is just difficult and just annoying enough that my bank isn't willing to do it. Please stop trying to change that.

When a company is doing something awful, it should have to leave the beaten path and work outside of the standard to do it. Because that helps us call out that they are doing something awful, and it helps us point to their solution and say, "no, that's not intended."

[sebk]

> but this is blocking authentication based on attributes of the device, correct?

Not precisely. It's requesting capabilities that the Yubikey is not configured to deliver so the browser doesn't show it as an option. There is no attestation or in fact no signed communication other than the RP requesting it in the registration. I don't understand what your desired behavior is here. Do you want to log in to Google with a bearer Yubikey (what do you do when it gets stolen?). Do you want all FIDO2 keys to require PINs, even if they're being used in a traditional "something you have" 2FA fashion?

> It absolutely does, it dictates how that login information gets shared between devices. As far as I'm concerned it's just another part of transport. (...) The lack of portability keeps the standard from being usable

In the same way that a keyboard dictates how a password is typed. Transport has a very well defined meaning in FIDO and it's not about transporting key material but rather signed challenges and responses.

Remember I'm suggesting a mechanism for open sync fabrics to exist, not the opposite. I simply don't see either the value in mandating interoperable sync fabrics, or for a particular vendor in control of the ecosystem like Apple or Google wanting to weaken the security posture of their keys given how the standard works if they allow them to be exported. Also remember that the standard doesn't just cater to users, it caters to these vendors implementing it as well, and more so.

> it's exactly what people say every time these conversations around DRM and fingerprinting come up

Except Webauthn doesn't have any fingerprinting capabilities beyond those in enterprise attestation (not regular attestation). In fact, it's much more privacy preserving that past alternatives. And fully realized, you wouldn't even need a username as an identifier with an RP that can be used to correlate you across services.

[danShumway]

> Do you want to log in to Google with a bearer Yubikey (what do you do when it gets stolen?)

I'd like to have that choice, yes. I don't think it would be good to act on that choice, but... Google should not be in charge of the device I use to submit a key. I mean, you talk about scope of the standard, a pin is a thing that exists locally on my device that I use to secure my keys. It's a local security measure, not something that's part of credentials for the service.

It's out of scope for Google to know anything about that. The scope of Google's login is the credentials that get submitted to Google. It's not really their business to know how my phone is locked (or by extension, how my passkey vault is locked).

> In the same way that a keyboard dictates how a password is typed

Well, the difference is that keyboards aren't currently blocking adoption of passkeys. Lack of portability is blocking adoption of passkeys. It's the biggest complaint people have.

If keyboards were a huge problem that made it harder to use passkeys, yes, it would be in scope to figure out some kind of solution to mitigate that problem.

> I simply don't see either the value in mandating interoperable sync fabrics

Because until users are confident that interoperability is going to to exist (and not just for one or two solutions, but also for the big environments like iOS/Android), this is going to continue to be a huge barrier to adoption and people are going to continue to warn against the spec.

The value is to address the complaint or people will keep complaining.

> Also remember that the standard doesn't just cater to users, it caters to these vendors implementing it as well, and more so.

Okay, then the users will stick with passwords. This is honestly kind of wild. The point of passkeys ought to be to make a usable solution for users. My heart bleeds for some of the richest companies on the planet, but they joined the FIDO Alliance, they wanted to build a usable standard. They signed up for this.

I have a solution that currently works (password vaults), and they want me to get rid of my solution and use theirs. So convince me. If they don't cater to users, users won't use passkeys, and it'll go the same way that every other key based authentication method for the web has gone. Remember, this is not the first time that companies have tried to get rid of passwords. Building a solution that doesn't have major caveats is really important if they want a different outcome from the previous efforts.

> Except Webauthn doesn't have any fingerprinting capabilities beyond those in enterprise attestation (not regular attestation) [...] In fact, it's much more privacy preserving that past alternatives

Only if it doesn't use attestation and doesn't get your device pinned down to X in 100,000. But that's not the important part, the important part is that attestation is literally DRM.

It is DRM to say "you will not be able to log into this service unless you're using a proprietary Apple/Android/Windows OS."

And will companies do that? Well, every single instance of attestation pre-WebAuthn -- literally every single instance -- is being used as DRM today. And you want that in the browser? If my bank is already using this to block me from logging into an app unless I'm on a proprietary OS, then of course they're going to do the same thing with web browsers as soon as they have access to tools to help them do so. You have to understand that, you have to understand that absent some kind of force blocking them from doing so (again, thanks Apple) attestation in the browser is most likely going to mean that I can't log into my bank from a web browser unless I have a proprietary OS to act as the authenticator. That's the world we're talking about.

Why wouldn't they use attestation here the same way as they've used every other attestation mechanism they've ever been handed? What is making you think that won't happen?

[sebk]

I think we both have exhausted our arguments regarding attestation. I understand why you don't want attestation to exist, and I believe you understand why I think it needed to exist in order for WebAuthn itself to exist. Like you, I hope it doesn't turn into a dystopia of every service requesting their own particular devices. So far, it doesn't look like it's going in that direction.

> I'd like to have that choice, yes. I don't think it would be good to act on that choice, but... Google should not be in charge of the device I use to submit a key

It's in Google's best interest to not damage their reputation with repeated break-ins to customer accounts and to reduce the overhead of an account recovery mechanism after an attack. It's the same rationale they use to not allow you to use "password" as a password, or why other services mandate 2FA. And again, Google isn't in control either, the authenticator is. Google (the RP) asks the browser (the client) for a user verification attribute. The authenticator is the one in charge of providing a response that sets that attribute. Without attestation, Google can't know if the authenticator did what it asked it to do.

> I have a solution that currently works (password vaults)

We're already seeing third-party sync fabric that don't use hardware elements without needing standard support. Dashlane already has it, 1Password is releasing it next month, and we're on a thread about initial support for it in KeePassXC. I'm sure soon after we'll see import capabilities for other password managers. Isn't this equivalent to the password manager you want to stick with?

All the extra discussion is around backing those sync fabrics with hardware (which is what I think will exist but outside of FIDO) and mandating implementors to allow exports (which I don't think will ever happen, nor do I personally want it or need it).