When a high definition (HD) multimedia contents such as audio and video travels from a device such as Blu-Ray player across DisplayPort, Digital Visual Interface (DVI), High-Definition Multimedia Interface (HDMI), Gigabit Video Interface (GVIF), or Unified Display Interface (UDI) connections, the signal is encrypted by High-bandwidth Digital Content Protection (HDCP), a form of digital copy protection developed by Intel Corporation.

The main objective of HDCP is to prevent the digital audio and video content from being eavesdropped, illegally played on devices that do not support HDCP, or been copied without authorization. HDCP performs the control by instructing transmitting device such as set-top box and Blu-ray disk player to check that the receiver such as HDTV is authorized to receive the data before starting to send the high definition data over the link.

For HDCP to perform encryption on the multimedia stream, an encryption key is required. And now, the master key of HDCP has leaked to Internet, which has been confirmed as real deal by Intel, the developer of HDCP. The HDCP master key can be used to crack the encryption which protects most HD and Blu-ray contents, effectively allow hackers to circumvent the DRM protection of HD video and audio content, especially on Blu-ray disc, which together with AACS,able to lock Blu-Ray movies to playback in approved hardware and software player only.

The master key of HDCP was leaked by hacker named IntelGlobalPR through announcement on Twitter. The master key itself is been published on pastebin.com, along with guide and instructions on how to use the master key to crack.

This is a forty times forty element matrix of fifty-six bit hexadecimal numbers.

To generate a source key, take a forty-bit number that (in binary) consists of twenty ones and twenty zeroes; this is the source KSV. Add together those twenty rows of the matrix that correspond to the ones in the KSV (with the lowest bit in the KSV corresponding to the first row), taking all elements modulo two to the power of fifty-six; this is the source private key.

To generate a sink key, do the same, but with the transposed matrix.

The leaked HDCP master key opens the door for HD media content stream to be intercepted, unlocked and decrypted with the master key when the signal is traveling from the source device to target device, allowing content to be copied or duplicated. The DRM protection of the HD media is effectively failed.

In addition, black-market manufacturers can build devices without having to pay the HDCP content license fees to Intel, and the device also also be made much better and superior with ability to do perform all acts and tasks that been restricted by HDCP protocol, such as ripping video. And with the master key, content providers cannot identify and shut off the devices remotely.

Intel foresees that hacker will be creating a computer chip with the master key embedded it, that could be used to decode Blu-ray discs, although a software decoder may be developed too. Due to the hardware requirement to implement the master key crack on HDCP, Intel assumes that the hack may be hard if not impossible to achieve. It’s interesting to see what steps Intel is going to take in order to remedy the leak of the master key and circumvent of HD content protection.

For people who interested, here’s the leaked master key for HDCP.

The HDCP encryption and decryption code based on the leaked master key has been released.

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