Everything about Hdcp totally explained
High-bandwidth Digital Content Protection (
HDCP) is a form of digital
copy protection developed by
Intel Corporation to prevent copying of digital audio and video content as it travels across
DisplayPort,
Digital Visual Interface (DVI),
High-Definition Multimedia Interface (HDMI),
Gigabit Video Interface (GVIF), or
Unified Display Interface (UDI) connections. The specification is
proprietary, and implementing HDCP requires a
license.
For
Digital Visual Interface (DVI) interfaces, HDCP is optional.
HDCP is licensed by Digital Content Protection, LLC, a subsidiary of Intel. In addition to an annual fee, licensed adopters agree to the conditions set forth in the HDCP License Agreement. For example, high-definition digital video sources must not transmit protected content to non-HDCP-compliant receivers. Additionally, DVD-Audio content is restricted to
CD-Audio quality or less on non-HDCP-digital audio outputs (analog audio outputs have no quality limits). Licensed adopters can't allow their devices to make copies of content, and must design their products in ways that "effectively frustrate attempts to defeat the content protection requirements." The technology sometimes causes handshaking problems, especially with older high-definition displays.
Specification
HDCP's stated purpose is to protect high definition content during transmission from a source device to a
display device. Three systems were developed to achieve that goal: 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.
Congress is still considering legislation that would implement something similar to the Broadcast Flag. The HDCP standard is more restrictive than the FCC's Digital Output Protection Technology requirement. HDCP bans compliant products from converting HDCP-restricted content to full-resolution analog form, presumably in an attempt to reduce the size of the
analog hole.
On
January 19,
2005, the European Information, Communications, and Consumer Electronics Technology Industry Associations (
EICTA) announced that HDCP is a required component of the European "
HD ready" label.
Microsoft's new operating system,
Windows Vista, utilizes this technology in the context of computer graphics cards and monitors.
Circumvention
Prior to HDCP, digital interfaces provided the same digital content without content protection between the player and display. As HDCP was introduced as a content protection standard, many non-HDCP-compliant devices were rendered unable to display HDCP-protected content unless fitted with a device to circumvent HDCP content protection, often referred to as "HDCP strippers." These are devices that remove the HDCP information from the video signal, leaving the video playable on non-HDCP-compliant displays.
Cryptanalysis
Cryptanalysis researchers demonstrated flaws in HDCP for the first time in 2001, prior to its adoption in any commercial product. Scott Crosby of
Carnegie Mellon University authored a paper with
Ian Goldberg, Robert Johnson, Dawn Song, and
David Wagner called "A Cryptanalysis of the High-bandwidth Digital Content Protection System". This paper was presented at ACM-CCS8 DRM Workshop on
November 5,
2001.
The authors conclude:
» HDCP's linear key exchange is a fundamental weakness. We can:
* Eavesdrop on any data
» * Clone any device with only their public key
* Avoid any blacklist on devices
» * Create new device keyvectors
* In aggregate, we can usurp the authority completely
For this attack you first have to break
Blom's scheme (the linear algebra-based key-exchange system). In the case of HDCP, you need a minimum of 39 device keys in order to reconstruct the secret symmetrical master matrix that has been used to compute all device keys.
Around the same time that Scott Crosby and co-authors were writing this paper,
Niels Ferguson independently claimed to have broken the HDCP scheme, but he didn't publish his research, citing legal concerns arising from the controversial
Digital Millennium Copyright Act.
The most well-known attack on HDCP is the conspiracy attack, where a number of devices is compromised and the information gathered is used to reproduce the private key of the central authority.
Interface support per version
(page 6 in 1.3 standard)
[Further Information]
Get more info on 'Hdcp'.
|
External Link Exchanges
Do you know how hard it is to get a link from a large encyclopaedia? Well we're different and will prove it. To get a link from us just add the following HTML to your site on a relevant page:
<a href="http://high-bandwidth_digital_content_protection.totallyexplained.com">High-bandwidth Digital Content Protection Totally Explained</a>
Then simply click through this link from your web page. Our crawlers will verify your link, extract the title of your web page and instantly add a link back to it. If you like you can remove the words Totally Explained and embed the link in article text.
As long as your link remains in place, we'll keep our link to you right here. Please play fair - our crawlers are watching. Your site must be closely related to this one's topic. Any kind of spamming, dubious practises or removing the link will result in your link from us being dropped and, potentially, your whole site being banned. |
