Analysis of Compact Disc Digital Rights Management

We studied dozens of compact discs and the copy protection schemes put on them. Some subtle but significant changes have taken place in CDs over the past few years and are well worth the attention of anyone who cares about who controls their computers.

Music publishers using the compact disc standard have introduced various copy protection schemes into the marketplace in the past several years, ostensibly in an effort to reduce sagging sales that the industry blames on illegal distribution of high-quality copies of compact discs. Over the course of three years, we performed a battery of tests against dozens of discs from various parts of the world to understand how these systems work.

Each of these schemes has unique features but a common thread emerges: exploiting differences between computer technology and basic players for compact disc digital audio. In some cases, the protected discs fail to meet the specifications established for interoperability of compact disc media. We also identified problems with computer software that failed to recognize certain types of standards-compliant discs that led consumers to report incorrectly that the discs were faulty.

Copy protection schemes come with several side-effects. These include a loss of functionality on some types of equipment, impaired playback quality on standard audio equipment, and risk of consumer privacy invasion.

The most important issue, however, is in the `ownership' of digital media standards. Where such standards were once governed by the producers of recording and playback equipment, an attempt to get consumers accustomed to a standard established by the recording industry itself seems underway.

This paper is the first in a series to document the findings of Interhack's Digital Media Project.

The paper is available in PostScript and PDF.