Every DVD player, including hardware consoles that plug into your television and software
players that you can download to your computer, has its own unique unlock key. This key is used to unlock the encryption key on the DVD. Every DVD has 400 copies of the same decryption key, each encrypted with every unlock code. The global secret: if you manage to get one unlock key, you can decrypt every DVD.
This is exactly what happened in the case of two Norwegian programmers that were able to hack into the CSS encrypting system. The two young men discovered that one licensee of DVD technology, Xing technologies, a subsidiary of RealNetwork, failed to follow licensing rules and encrypt their decryption key. With this unencrypted key in hand, the two men were able to reverse-engineer the XingDVD player. Because the unlock key for the CSS encrypting system is only 5 bytes long, the programmers were able to guess roughly 170 other keys. So even if all future DVD movies remove the Xing key, DeCSS has a plethora of other keys to choose from.
Breaking DVD's encryption was considered extremely difficultat first, but once the first key was discovered, the rest fell with ease, since the crackers were able to use their original, valid key as a launch point to find more valid decryption keys. However, the hackers claim that their intent was never to pirate DVD content but rather just to find a means to play DVD’s on their own Linux machines, for which a DVD player did not yet exist.
Linux is an opensource operating system that has been in existence for a number of years. It was developed by Linus Torvalds at the University of Helsinki (now Transmedia in California) and first released in October 1985. Linux is based on the open source concept where the actual source code is freely distributed. The system consists of the Linux core, known as the kernel, and a large collection of software applications formally known as the distribution. Within the Linux community individuals are encouraged to modify any source code to suit there specific needs.
At the time of hacking, computer DVD playback had only been available on Microsoft Windows and MAC systems, individuals who chose to use alternative operating systems did not yet have a means to watch DVD movies on their systems. Many believed that the DVD industry had refused to support Linux because the market share for Linux is too small for reasonable profits. Consequently, several Linux user groups started to work toward developing a DVD player for Linux. One of the groups, LSDVD, had created a collaboration working on a fully licensed DVD movie player. The group was working to make the software available for a nominal fee to cover the costs of licensing. Another group, LiViD, was trying to make a true open source DVD movie player that would be available free of charge. Another group of programmers calling itself the Masters of Reverse Engineering (MoRE) got involved in the "DVD for Linux" movement.
To get the DVD player working, the programmers needed to figure out how the CSS algorithm worked. MoRE was the group that discovered the unencrypted key and reverse-engineered a software DVD player from Xing.
The questions, to date, have been whether or not this act was completely ethical, as well as whether it was completely legal. As far as legality is concerned, there are legal questions regarding the interpretation of The Digital Millenium Copyright Act (DMCA). The DMCA states that "reverse-engineering on the basis of interoperability" is legal, but the DVD CCA and the MPAA believe that the DMCA protects CSS because it is copyrighted.
The MPAA claims that the Linux argument is a false issue. The organization says that it was always in the interest of the Motion Picture industry that there be as many legitimately licensed DVD players as possible, including those using non-Windows operating systems. As proof that the Motion Picture industry intended to include Linux users, the development of two, separate, licensed DVD players for Linux systems - which use the CSS system - were recently announced. Sigma Designs (www.sigmadesigns.com) and InterVideo Inc. (www.intervideo.com) both announced the roll-out of licensed, legal Linux-based DVD players.
The MPAA also maintains that the argument that DeCSS was written for Linux players is simply false. The freely distributed DeCSS utility was ultimately written for Windows-based software, not Linux.