So what’s the number? Well there is an ongoing legal battle of the Motion Pictures Association of America and the makers of the HD-DVD system against the right of the public to state a simple number. According to them the string “09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0″ contravenes the Digital Millennium Copyright Act. Many website owners have been given cease and desist orders, and some sites have disappeared entirely from the net.
See Wired's The New HD-DVD/Blu-Ray Hack: What It Might Mean For Us for an in-temporal-context overview and Wikipedia's AACS encryption key controversy article for the ongoing story.