davidwr's Journal: How to detect illegal movies and other content

Update2: Original entry deleted, re-posted as a private entry.

Update: This stream-of-consciousness half-baked journal entry wasn't supposed to be on FireHose. I took the default marking "Publish: Share this with other Slashdot users." I did NOT choose "Publicize: Submit this story to be posted to the Slashdot front page."

Sorry for wasting your time everyone.
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How to detect illegal movies:

Break movie file up into chunks. Fewer chunks mean simpler encoding, shorter chunks mean simpler verification.

Chunks by time are best because DVDs are already marked by scene.

For each scene, create a few dozen "markers" that can be in one of at least two states. For example, a pixel can have an RGB color of {100,100,100} or {100,100,101}, a sound can be slightly altered, or the time can be slightly compressed or dilated.

For each customer make a unique version of the scene. With 30 markers you have a billion combinations.

Digitally sign each scene.

On playback, the player will show the identity of the signer, along with a trademarked "authentic" symbol. Scenes that are not signed will be labeled as "not authenticated." Scenes whose signatures don't check out will be marked as "authentication failed, possibly corrupted." This can be turned off by the customer, and will be most of the time.

Movie studios can use this as evidence of an illegally copied movie in two ways:
1) complete scenes with the authentication tampered with are most likely bootleg.
2) complete scenes which are untampered can be traced to the original buyer.
3) file-sharing services can use the presence or absence of authentication markers, plus matching of the clip against a database, to determine if the copy is authorized for use on that service.

This can be applied to other content and media as well.