[Retr0id]

A DRM system is, abstractly, a black box that contains some initial static key material, which is used to identify+authenticate the device and load in more keys at runtime, typically over some network protocol. The DRM uses those dynamically provisioned keys to decrypt the content.

For hardware DRM schemes, the initial key material is typically provisioned during manufacturing.

Since the server-side is able to identify the client device, they can in theory fingerprint the content if they want to. That way if someone cracks and shares the content, they can look at the fingerprint and figure out which device (and which account) leaked it - and then ban them.

I've never seen direct evidence that Netflix fingerprints their 4K content (although I've never properly looked), so I suspect the device-burning thing might be a bit of an urban legend. But it is technically plausible.

[direwolf20]

If it wasn't real, Netflix would leak 4Ks more frequently. We're inferring by a third-order effect.