High-bandwidth Digital Content Protection
[5][6][7] For example, the device cannot be designed to copy; it must "frustrate attempts to defeat the content protection requirements";[7] it must not transmit high definition protected video to non-HDCP receivers; and DVD-Audio works can be played only at CD-audio quality[7] by non-HDCP digital audio outputs (analog audio outputs have no quality limits).
[11] In practical terms, the impact of the crack has been described as "the digital equivalent of pointing a video camera at the TV", and of limited importance for consumers because the encryption of high-definition discs has been attacked directly, with the loss of interactive features like menus.
If a particular set of keys is compromised, their corresponding KSV is added to a revocation list burned onto new discs in the DVD and Blu-ray formats.
)[4] In the United States, the Federal Communications Commission (FCC) approved HDCP as a "Digital Output Protection Technology" on 4 August 2004.
[13] The FCC's Broadcast flag regulations, which were struck down by the United States Court of Appeals for the District of Columbia Circuit, would have required DRM technologies on all digital outputs from HDTV signal demodulators.
[17] In 2001, Scott Crosby of Carnegie Mellon University wrote a paper with Ian Goldberg, Robert Johnson, Dawn Song, and David Wagner called "A Cryptanalysis of the High-bandwidth Digital Content Protection System", and presented it at ACM-CCS8 DRM Workshop on 5 November.
Around the same time, Niels Ferguson independently claimed to have broken the HDCP scheme, but he did not publish his research, citing legal concerns arising from the controversial Digital Millennium Copyright Act.
[19] In November 2011 Professor Tim Güneysu of Ruhr-Universität Bochum revealed he had broken the HDCP 1.3 encryption standard.
[20][21] Intel has threatened legal action against anyone producing hardware to circumvent the HDCP, possibly under the Digital Millennium Copyright Act.
Further, the input parameters for the XOR and the AES above it are fixed from the receiver side, meaning the transmitter can enforce repeating the same operation.
Such a setting allows an attacker to monitor the pairing protocol, repeat it with a small change and extract the Km key.
[26] On 31 December 2015, Warner Bros and Digital Content Protection, LLC (DCP, the owners of HDCP) filed a lawsuit against LegendSky.
[27][28] Nevertheless, the lawsuit was ultimately dropped after LegendSky argued that the device did not "strip" HDCP content protection but rather downgraded it to an older version, a measure which is explicitly permitted in DCP's licensing manual.
[31][32][33] Edward Felten wrote "the main practical effect of HDCP has been to create one more way in which your electronics could fail to work properly with your TV," and concluded in the aftermath of the master key fiasco that HDCP has been "less a security system than a tool for shaping the consumer electronics market.
[35] There is also the problem that all Apple laptop products, presumably in order to reduce switching time, when confronted with an HDCP-compliant sink device, automatically enable HDCP encryption from the HDMI / Mini DisplayPort / USB-C connector port.
[36] Some sink devices have the ability to disable their HDCP reporting entirely, however, preventing this issue from blocking content to videoconferencing or recording.
Version 2.x employs industry-standard encryption algorithms, such as 128-bit AES with 3072 or 1024-bit RSA public key and 256-bit HMAC-SHA256 hash function.
