Another month, another security faux-pas. This time, Hollywood's advanced access content system (AACS) for securing high-definition video (HD DVDs) has come under fire.

A hacker calling himself arnezami has claimed on a discussion board that he has found the master key to the copy protection process, firstly by reading the volume key, then identifying the processing key. Combining the two allowed him to unlock the copy protection. No hacking tools or reverse engineering was required, according to arnezami.

This attack will, in theory, work for every Blu-ray and HD DVD disc released so far. Although content owners could change or revoke the keys in question, the crackers argue that the hack will reveal the new ones just as easily.

AACS was founded by IBM, Intel Corporation, Microsoft, Panasonic (Matsushita Electric), Sony, Toshiba, the Walt Disney Company and Warner Bros Studios.