Cracking Uncovered: Protection against Unsanctioned CD Copying
by Kaspersky, Kris
ISBN 1-931769-33-8. 422 pages. $39.95. Index. CDROM
Reviewed by Robert Bruen September 16, 2004
In spite of the increasing use of DVDs, I expect CDs will be with us for a quite a while. We still see lots of material released on CDs, stuff we will keep for a long time, even as we add DVDs to our collection. Thus, a book explaining low level details of the workings of a CD is useful. The author presents the book as protection against copying, but the knowledge is the same whether you are trying to protect or trying to crack. As I like to say, there is very little which can replace expertise.
Because the book is aimed at those who want to protect CDs from being copied, several schemes are nicely detailed. One of the first things that comes up is, of course, "there is no absolute protection against copying for optical media." The second realization is "Struggling against professional crackers is absolutely pointless." The end result is that protections are built into CD creator software and firmware of CD players. The two main types of protection are non-standard formatting and binding to the physical characteristics of the media surface.
CD copying software might read a protection mechanism and refuse to copy from a CD to somewhere else. If the software does not pay attention to the protection when reading then there is not much protection. The problem extends into the business domain in addition to the technical domain. For example, the inventors of the CD, Philips, does not want anyone to call anything a "Compact Disk" unless it conforms to the standards. This means no protection mechanisms and a disclaimer on the pseudo CD with any form of protection. In many ways, this makes the CD a people's technology. On the other hand, the piracy market involving CDs is huge for the same reason.
As long as the CD can be read, there will be a way to copy it. Given the situation where CDs are very common, useful, and all can copied, then we mights as well understand the details of how it works. In order to explain how to protect the CD from copying, Kaspersky firsts explains how the CD itself is structured and formatted. Naturally, how the protection mechanism can attacked is also shown. For those in the underground, this is not really news; perhaps, though, there is something to be learned. For those who have not really paid any attention, this will be eye opening. A number of standard programs are analyzed, for example one program that adds watermarks to CDs, as well as some code to learn how they work,
In another chapter, we find methods for revealing protection mechanisms. As we get closer to the hardware, more math is required. If terms like polynomial or Galois Fields are new to you, the chapter introducing them is a good introduction. The author expresses a bit of disgust at the math taught in public schools and colleges, which makes his approach a little different. This chapter is mainly about Reed-Solomon error correcting codes and their application to CDROMs.
The rest of the book is is revealing for driver information, hardware interfaces and other low level topics. Although some of the book's contents are available elsewhere, this seems be the best source. CD Cracking Uncovered is written by someone who knows his stuff and is recommended for anyone who also wants to know his stuff.