[axel77]

IMHO All this DRM will fail. Even if there is the perfect DRM technique, it will only affect you to do a one time analog/digital conversation on audio, or a onetime OCR on books.

Put the e-reader head on a scanner, have a software pressing "next page" for you, and when OCR became good enough to locate letters, and recreate a pdf that much fits the original, your are done.

In worst case, you have soon a free image pdf available (okay non-searchable, and larger) but thats it.

The scanner is only the worst scenario of the perfect DRM tech, otherwise speaking encryption-wise you always have the problem, that you have to give "the foe" a decryption device, so he can actually see/hear it.