Polynomial Arithmetic and Galois Fields

Chapter List

Chapter 3: Practical Advice on Urgent System Recovery

Chapter 4: Interfaces for Interaction with the Hardware

Chapter 5: Methods of Revealing Protection Mechanisms

The sector level of interaction has been an attraction for developers of CD protection mechanisms, as well as for the developers of utilities designed for the copying of protected discs. The reading and writing of Raw sectors is even more promising , because it is the lowest possible level of interaction with the disc that can be supported by standard drives . In fact, most protection mechanisms operate this way. Some of them hide the key information in subcode channels, while others in some way corrupt ECC/EDC codes, or use non-standard formatting and similar methods.

Methods of operating with discs at the sector level are numerous , and descriptions of about dozen of these will be provided below. Most of the methods that will be discussed here are intended exclusively for Windows NT/W2K/XP and do not work on Windows 9x, which is likely to go the way of the wooly mammoth interest in this operating system is fading swiftly, both for end users and for programmers. While Windows 9x will stay afloat for a while yet, in the long term its not worth betting on, especially in view of the fact that Windows 9x does not support multiprocessor systems, and the triumphant arrival of Hyper-Threading is just around the corner.

Note 

Hyper-Threading technology is based on the implementation of Simultaneous Multi-Threading (SMT). In fact, this technology represents an intermediate stage between multithreading carried out in multiprocessor systems and parallelism at the level of instructions present in single-processor systems.

Since disc access at the sector level is initially oriented towards the developers of protection mechanisms, this section has a pronounced focus on the thwarting of hackers. It describes not only methods of low-level device management, but also discusses the internal function of protection mechanisms.

Note 

Some variations of protection against unauthorized copying cannot principally be cracked using standard home appliances. In particular, audio CD protection mechanisms based on an incorrect TOC (Table of Contents) render such a disc unreadable by computer CD-ROM drives. However, on audio players that do not delve into examining every TOC detail, such discs can be played satisfactorily. The only way of copying such a disc in a digital format is by patching the firmware of the CD-ROM drive to remove some of the extra checks, or by disassembling the drive to hotswap the disc. More details on this topic will be provided in Chapter xxxx.

Therefore, it is indeed unwise to overestimate protection mechanisms designed to prevent the unauthorized copying of CDs.