In February, Apple CEO Steve Jobs urged people to "[i]magine a world where every online store sells DRM-free music encoded in open licensable formats," saying that Apple would embrace the possibility "in a heartbeat" if the music labels dropped their insistence on digital rights management (DRM) technology for music.

But a new Apple patent application filed in October, 2006 and published on Thursday suggests that Apple doesn't expect to live in the world evoked by Jobs.

"The proliferation of digital content and the ease with which it is created, manipulated, copied, and distributed has led to new challenges for digital content creators, owners, and providers," the patent application, "Decoupling Rights In A Digital Content Unit From Download," explains. "Those having vested interests in the content have to be especially careful in determining the best means to effectively manage the distribution, use and monitoring of their digital content assets and protect them from piracy."

The copy protection system describes both a scheme for "for transcrypting or converting a digital content unit encrypted with a given key into a decryptable copy of the digital content unit" and a scheme for disassociating DRM from digital content.

In this second manifestation, the technology might be better described as "digital rights assignment" since it would serve to authorize the use of an existing digital file.

Such a system would allow Apple to, for example, authorize viewing of video content that already resided on a customer's computer. Presumably, this content could be preloaded on a device, with access granted for a fee. Or it might be used to encourage the conversion of unauthorized copies of digital content into paid, authorized copies.

The patent application shows that Apple has been developing the technical infrastructure for a subscription service for digital content. Apple to date has only offered digital content for sale and it may see no reason to deviate from that model. But the technology described suggests that Apple could offer a subscription service for content if it wanted.

The patent also envisions media sharing along the lines of Microsoft's Zune music player. It describes a sharing scenario involving fictional characters "Alice" and "Bob," who have starred in many patent applications and explanations of encryption.

"[I]f Alice, for example, purchases an encrypted digital content unit from the digital content store and Bob has access to a copy of the encrypted digital content unit obtained by Alice, Bob will be able to obtain from the digital content store the legal right to access the copy," the patent application explains. "Bob will be able to decrypt the copy of the encrypted digital content unit for his enjoyment even though the encrypted digital content unit was encrypted with a key associated with Alice. Bob will be able to access the digital content in the copy without having to download another copy from the digital content store."

Apple won't comment on whether or not it might deploy such systems. But clearly its researchers are imagining a very different world than the DRM-free wonderland described by Steve Jobs.