The DRM scheme most widely deployed predates the coining of the term DRM. It’s present on all audio CDs that conform to the Compact Disc Digital Audio (CDDA) standard. This scheme sets two bits on a disc. One bit indicates whether the material is copyrighted and the other bit indicates whether the material is a copy. A CD duplicator that conforms to the specification will not allow copies of copies of copyrighted material to be made.
The designers of this scheme didn’t take into account two developments. The first was audio compression. In the mid 1990s, MP3 (MPEG-I, audio layer 3) was the state of the art for audio compression. It enabled a CD to be stored at an eighth of its size with an acceptable loss of quality. Suddenly a 1GB hard drive could store 12 CDs worth of music, rather than one. Because MP3s didn’t respect the single-copy rule, they effectively bypassed the system.
The second occurrence that the designers of the CDDA standard didn’t foresee was the widespread adoption of CD writers in computers. (It was originally imagined that CDs would be used to distribute music and large applications, while CD writers, used for mastering, would remain expensive.)
Modern DRM systems are more sophisticated. The iTunes Music Store (iTMS) sells MPEG-4 audio files protected by Apple’s FairPlay DRM. When you purchase music from iTMS, it arrives encrypted. Any device that’s authorized to play this music receives a copy of the decryption key. The server keeps track of which clients are authorized, limiting you to a small number of copies of iTunes that can play your music, although each copy of iTunes is allowed to share the key with an unlimited number of iPods.
So far, no one has cracked the latest version of FairPlay. This means that any music bought from iTMS can be used only in ways authorized by Apple. For many users, this system may be acceptable. But Apple reserves the right to change what they allow; they’ve done this already, reducing the number of times a playlist can be burned to CD while increasing the number of computers that can be authorized.
Note that the restrictions imposed by DRM are not technical. I have a mobile phone that can play MPEG-4 audio files, including those encoded using iTunes, but it can’t play music purchased from iTMS. Here, DRM is being used to promote vendor lock-in, something very different from the claims that it combats piracy.
It’s worth noting that people who decide to pirate their music have none of these restrictions. Steve Jobs, Apple’s CEO, has stated that he considers music piracy to be his biggest competitor. Apple can’t compete on price, he claims, but they can compete on quality of service. It seems strange, therefore, that they would add something to their product that reduces its utility.