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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+ re-secured, Slysoft beaten )〕 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. == Capabilities == BD+ is effectively a virtual machine embedded in authorized players. It allows content providers to include executable programs on Blu-ray Discs. Such programs can: * examine the host environment, to see if the player has been tampered with. Every licensed playback device manufacturer must provide the BD+ licensing authority with memory footprints that identify their devices. * verify that the player's keys have not been changed. * execute native code, possibly to patch an otherwise insecure system. * transform the audio and video output. Parts of the content will not be viewable without letting the BD+-program repair it. If a playback device manufacturer finds that its devices have been hacked, it can potentially release BD+-code that detects and circumvents the vulnerability. These programs can then be included in all new disc releases. The specifications of the BD+ virtual machine are only officially available to licensed device manufacturers. A list of licensed adopters is available from the BD+ website.〔(BD+ Technologies LLC )〕 Both SlySoft and members of the Doom9 forum have reverse engineered the virtual machine specification, however. According to the reverse-engineered specification, the virtual machine consists of a 32-bit big endian DLX like processor with 4MB of RAM. It has 32 32-bit registers available for use. A TRAP instruction is used to allow the virtual machine host to perform more complex actions as system calls.〔(Doom9 thread on reverse engineering )〕 To prevent simple, static disassembly of the BD+ code, an instruction filter is available that can perform an XOR operation on an opcode before executing it. By varying the instruction filter at runtime, the compiler can force an adversary to trace through the code at runtime before they can fully disassemble it.〔(Doom9 thread on instruction filter )〕 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「BD+」の詳細全文を読む スポンサード リンク
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