In the past, when information was stored in analog form, the
copying and redistribution of such information, while problematic, did not account for as much economic loss as is possible today.
Today's
high fidelity systems are very accurate, but they are not flawless.
If multiple generations of recording (e.g., cascaded recordings) were undertaken, the resulting product would be noticeably inferior to the original.
Similarly, when multiple generations of photocopies of an image are made, the quality of the resulting image is typically poor, with many dark and light areas that were not present in the original image.
As a result of the ability to copy a file with no loss of fidelity, it is now almost impossible to differentiate a
digital copy from the digital original.
Additionally, print publishers hesitate to expand into the network marketplace because they are unable to control (in the sense of receiving compensation in return for rights) secondary distribution of their products as well as incorporation of their products into derivative products.
Such changes in cost and convenience of necessity
impact business decisions concerning producing, distributing, promoting, and marketing.
Of those prior art systems which make some use of
encryption, none protects the data after it has been decrypted.
Further, in all of the prior art, access is all or nothing, that is, once access is granted, it cannot be controlled in any other ways.
This makes it difficult to control
copying, secondary distribution, as well as to obtain
payment for all uses.
The safety problem is closely related to the fundamental flaw in
Discretionary Access Control (DAC) that malicious code can modify the protection state.
The prior art, including cryptographic processes, tokens, dongles, so-called "uncopyable" media, various
executable software protection schemes, and
executable software for printing that places an identifier on all printed output in a fashion not apparent to a human, fails to limit either secondary distribution or distribution of derivative works.
The problem of copying by the authorized user is simply not addressed.
Schemes that include identifiers on printed material, although they may aid in identifying the source of copied material, do not prevent secondary distribution.
However, once access has been granted to information that information is subject to manipulation and redistribution without further limitation.
Further, dongles have proven to be unpopular because of the need to keep track of them and ensure that they are separately secured.
Uncopyable media, generally used either to control distribution of information or to control usage of
executable software, are unpopular because of the user's inability to create a
backup copy.
Further, most so-called uncopyable disks have fallen victim to general-purpose duplication programs, rendering their protection useless.
Even where partially effective, the uncopyable disk did not serve as a deterrent to capturing information and redistributing it.
However, such a
security function may be capable of being defeated by a knowledgeable attacker.
A successful
attack is judged as being beyond normal practicality.
Capture of an analog output results in some degradation of
signal quality.
But the market for bootleg copies of videos, for example, appears to be insensitive to such quality if the price is right.
A captured
digital signal suffers degradation of quality only as a result of bit errors (i.e., if the data capture was not completely accurate).
Creating an unauthorized local copy, or disseminating the data without
authorization each results in an original-quality copy without compensation to the owner.
One manifestation of this
threat is in uncontrolled hardware.
Semiconductor memory is volatile and does not retain data when power is removed.