client.register() 'domain' option doesn't seem to work

[knutesears]

Got this error on my server:

Error: Unexpected ClientData origin: https://www.lexluv.org

...when it was working fine without the www subdomain. Changed client code to:

        const pk_registration = await webAuthClient.register({
            user: {
                name: uname,                          // lc, canonical
                displayName: displayName,   // users full name || non lc'd username
            },
            challenge: pk_nonce,
            domain: 'lexluv.org',            // www.lexluv.org from window.location.hostname was making it choke

            /* possibly other options; see:  https://webauthn.passwordless.id/registration/  */
        })

Still get the same error. So, grabbed pk_registration.response.clientDataJSON:

"eyJ0eXBlIjoid2ViYXV0aG4uY3JlYXRlIiwiY2hhbGxlbmdlIjoiV1RHa2FHVU9MUE5JU1VNOE45R1NjRTlZIiwib3JpZ2luIjoiaHR0cHM6Ly93d3cudHh0Z21zLmNvbSIsImNyb3NzT3JpZ2luIjpmYWxzZX0="

...decoded it to:

{"type":"webauthn.create","challenge":"WTGkaGUOLPNISUM8N9GScE9Y","origin":"https://www.lexluv.org","crossOrigin":false}

It would appear that register() is not acting on the 'domain' option at all. I note that the registration client data is using the 'origin', which includes the protocol. Maybe I'll look at the module source, but at a minimum the docs are wrong.

[dagnelies]

To tell the truth, this option might indeed be buggy. It's the only option not properly tested😳. I'll need to dig into, but I'm short on time right now.

[dagnelies]

At first sight, the registration correct but the verification is wrong. To test it, use another subdomain and it should be able to use the same passkeys. In other words, using a page on a.txtgms.com and b.txtgms.com should be able to use the same passkeys if registered with parent domain txtgms.com. ...once I fix the verification 🙄

[knutesears]

Thx for checking it out. Not a biggie to me, just thought I should report it. Started when my friend typed www.site.com into browser -- who does that anymore? I fixed that with a hammer by just redirecting www.domain to domain, but I can imagine some people would want to issue keys on www.site.com and have them be valid for site.com -- but maybe that's a security issue. Keys for site.com should work on sub.site.com, but not the other way around, correct? And www. is just a special case of that.

p.s. Followed the discussion at w3c/webauthn#1749 and totally agree with you. It's obtuse that the API won't even give a passkey existence indicator for the selfsame web site. I have an id (browser_id = ${ip_addr}-${timestamp}) that replicates between localStorage and Cookies, so at least I have a shot of knowing if the user has a passkey on that browser.

[dagnelies]

The default is fixed on the exact domain it is used. So that a passkey generated at "sub.example.com" is only valid for this subdomain, not "example.com" nor "child.sub.example.com".

The domain parameter can be used to reference a parent domain. For example "auth.example.com" could set domain to "example.com" during registration. That way, any authentication in a subdomain "whatever.example.com" could also use the same passkey (by setting "example.com" as domain too). ...if it worked properly that is.

[knutesears]

Thank you for the clarification -- I think I get it now.

And thank you for making this library. I shopped around, and yours is one of the cleanest (and not written by some company trying to sell some subscription-based passkey snakeoil;)

[dagnelies]

Thanks for the kind words. I appreciate that a lot.