I had an interesting thought about distributing digitized, DRM-less versions of non-digital or DRM-restricted copyrighted works: What if you distributed an encrypted digital copy of the work, and the decryption key was derived from the contents of the work itself? For a book: “take the SHA512 hash of words 7, 35, and and 79 from page 67, appended together with a space in between. Use the resulting hash to as the key to decrypt the file.” (Of course a longer, more complicated key would probably be advisable in practice.)

I'm not a lawyer… but it seems like distributing an encrypted copy of something (without outright including the key) can’t be illegal – without the key they're just random bits! And since the key has to be derived from the original content, the receiver/decrypter is proving they have an original, and thus under fair use laws are allowed to have personal, decrypted copies for backup/convenience (I think; MAFIAA is working hard to erode those rights.) The person might not legally have full rights to it (e.g., they just grabbed a copy from the library to decrypt the digital copy), but if we're nitpicking about that, they could just as well make an illegal copy of the borrowed copy, without bothering with downloading and decryption.

I imagine this is not an original idea from me, so I'll have to see if anyone has written further on it or tested it in courts.