Error: Unexpected authenticator counter: 0 (should be > 0)

[jmatsushita]

When using the playground both in Chrome on Desktop and Mobile (iOS):

• I can Register Device succesfully with the default settings
• When I press Login the client side details are filled up
• But a toaster shows up with this error Error: Unexpected authenticator counter: 0 (should be > 0) and the second server side area shows:

Resulting into:
...

[dagnelies]

According to the WebAuthn specification, this counter should increase each time authentication is triggered with the key... In theory. In practice, Windows and Android do respect that, but Apple sets it to zero... And I don't actually know if they increase it at all since I don't have such a device to test.

I recommend to use counter:-1 to verify the first attestation instead of 0. And I would be curious if they properly increase this counter afterwards.

[dagnelies]

I will also edit the playground accordingly soon