https://en.wikipedia.org/wiki/AACS_encryption_key_controversy

A controversy surrounding the AACS processing key arose in April 2007 when the Motion Picture Association of America and the Advanced Access Content System Licensing Administrator, LLC (AACS LA) began issuing cease and desist letters to websites publishing a 128-bit (16-byte) number, represented in hexadecimal as 09 F9 11 02 9D 74 E3 5B D8 41 56 C5 63 56 88 C0 (commonly referred to as 09 F9), a cryptographic key for HD DVDs and Blu-ray Discs.

The controversy was further escalated in early May 2007, when aggregate news site Digg received a DMCA cease and desist notice and then removed numerous articles on the matter and banned users reposting the information. This sparked what some describe as a digital revolt or “cyber-riot”, in which users posted and spread the key on Digg, and throughout the Internet en masse, thereby leading to a Streisand effect.