[cesarb]

> I'm assuming "attester" here means "hardware authenticator." How is the attestation low entropy if it's presumably signed by a key that is unique & resident to my device?

From what I understood, the "attester" is a remote server, which signs the attestation with its own key, after somehow verifying that the browser and operating system and drivers and machine is not running any code that this remote server does not completely trust. That key can be used at most to identify the remote server, which is supposedly shared by a wide number of devices.

Yes, this means that your browser depends on having a working connection to that remote server for every attestation it makes, and that if that remote server colludes with the web page (or is compromised), it can leak your identity.

[xg15]

Also, there probably will be per-device keys, it's just that they are only used in the communication between the attester and the device, and not exposed to the web page.

So you're at the complete mercy of the attester (and of whatever deals it made with the sites) but the sites technically can't use the token to track you. Privacy!!!

[goku12]

The WEI spec talks at length about how ads provide revenue for the web publisher. In that context, I'm pretty sure that the 'environment' they're talking about must ensure that the ads are shown. This would mean that the attester has to invasively check the browser/app to ensure that no ad blocker is running. That would mean that the attester is most likely a proprietary application running on the user's device.