>- The web page executing in a user's web browser
>- A third party that can “attest” to the device a web browser is executing on, referred to as the attester
>- The web developers server which can remotely verify attestation responses and act on this information.
Chome only for now but I imagine after it's pushed to Chromium and all the browser based on that Mozilla will implement it too (just like all the other DRM FF has now).
Oh well, the world we live in