[derefr]

The "real honest-to-god TPM" I was talking about? That would also be the basis for a DCCP-like system that actually worked indefinitely. Communications between your device and your display would be encrypted with keys that aren't extractable from the memory of either.

Of course, the signal is going to end up decrypted at the DAC interface, and you can always capture it there. But that doesn't give you the original encrypted data stream; it just gives you the result of applying the wrapper program to the encrypted data stream. Which might involve, say, per-customer watermarking, enabling them to very firmly trace the source of a given leak.

(And the watermark could be constructed so that anything that you could do to remove it would involve severely reducing the fidelity of the video. You might be able to restore the fidelity by gathering and averaging many different customers' streams, but not if the watermark involves "signal" rather than "noise"—for example, assuming a cartoon, realtime replacement of the patterns on a character's clothes with a catalogue of different textures, which would be made to average out to harsh static. Remember, your own computer is doing the processing to insert this stuff—it can afford to give you slow, individual attention, in a way that the provider's CDN servers just can't.)

[comex]

You can't extract the keys, but you can recover a copy of the entire program, which lets you do the same thing: impersonate the 'TPM'. The only difference is that, as you say, any per-user transformation of the data could be done on the user's PC rather than in the cloud somewhere - but considering the orders of magnitude of overhead the obfuscation would probably impose even if the current research is vastly improved on (though I'm just guessing), I suspect it wouldn't be worth it in practice.

[dexterdog]

So then you use two unique captures of the same material to find the deltas and munge away.