BD+ is a component of the Blu-ray Disc Digital Rights Management system. It was developed by Cryptography Research Inc. and is based on their Self-Protecting Digital Content concept. Its intent was to prevent unauthorized copies of Blu-ray discs and the playback of Blu-ray media using unauthorized devices.
While BD+ has not stemmed the flow of "cracked" high definition content, it has made it necessary for those who wish to copy Blu-ray movies to reinvest resources to break each new version of security code.
BD+ played a pivotal role in the format war of Blu-ray and HD DVD. Several studios cited Blu-ray Disc's adoption of the BD+ anti-copying system as the reason they supported Blu-ray Disc over HD DVD. The copy protection scheme was to take "10 years" to crack, according to Richard Doherty, an analyst with Envisioneering Group.
On 19 November 2007, Macrovision announced that it planned to acquire the SPDC technology (including patents and software code) from CRI for US$45 million in cash plus stock warrants.
On 7 July 2011, Irdeto acquired BD+ content protection technology for Blu-ray discs from Rovi_Corporation.
Read more about BD+: Capabilities, Virtual Machine, Reverse Engineering and Emulation of BD+ Implementations