In an attempt to capture some of the current AACS (Advanced Access Content System, copy-restriction technology for new-format DVDs) controversy, here is some background information.
The whole controversy started when someone managed to figure out what the 16-digit hexadecimal key is that currently encrypts new-format DVDs. Although knowledge of this rather simple number doesn’t in-itself decrypt DVDs (some software is needed too), it’s enough that the AACS organization began sending take-down notices to sites posting the key, and revoked it. (Meaning, I gather, that it will be useful for decrypting newly-published movies.)
Free-speech and technology advocates revolted in a variety of ways, complaining essentially that a randomly-generated 32-digit hexadecimal number was not deserving of copyright protection. The more take-down notices were issued, the more sites posted the number.
AACS vows to fight people who publish the key
Legally it appears AACS may actually be able to enforce the restriction on publication under current laws like the DMCA, although it’s unclear how practical that is, or if the courts would uphold the enforcement in this specific case… however, given the current Supreme Court makeup, I suspect the Constitutionality would be upheld.