Advanced Access Content System: Difference between revisions

Revision as of 12:47, 14 June 2017

Revision as of 08:03, 27 June 2017

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To read the Volume ID, a cryptographic [[Public key certificate|certificate]] (the ''Private Host Key'') signed by the AACS LA is required. However, this has been circumvented by modifying the firmware of some HD DVD and Blu-ray drives.<ref name=arstechnica-aacs>{{cite web

|url = https://arstechnica.com/news.ars/post/20070415-aacs-cracks-cannot-be-revoked-says-hacker.html

|title = New AACS cracks cannot be revoked, says hacker.

|accessdate = 2007-05-04

|first =Jeremy Jeremy

|last =Reimer Reimer

|date=15 April 2007

|work=Ars Technica

|work=Ars Technica| archiveurl= https://web.archive.org/web/20070504171556/http://arstechnica.com/news.ars/post/20070415-aacs-cracks-cannot-be-revoked-says-hacker.html?| archivedate= 4 May 2007 <!--DASHBot-->| deadurl= no}}</ref><ref>{{cite web

|archivedate=4 May 2007

|deadurl=no

}}</ref><ref>{{cite web

|url = http://forum.doom9.org/showthread.php?t=124294

|title = Got VolumeID without AACS authentication :)

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{{main|Image Constraint Token}}

AACS-compliant players must follow guidelines pertaining to outputs over analog connections. This is set by a flag called the Image Constraint Token (ICT), which restricts the resolution for analog outputs to 960×540. Full 1920×1080 resolution is restricted to HDMI or DVI outputs that support [[High-bandwidth Digital Content Protection|HDCP]]. The decision to set the flag to restrict output ("down-convert") is left to the content provider. Warner Pictures is a proponent of ICT, and it is expected that Paramount and Universal will implement down-conversion as well.<ref>{{cite web|url=http://www.videobusiness.com/article/CA6300812.html |title=High-def ‘down-converting’ forced |accessdate=2007-05-04 |date=19 January 2006 |last=Sweeting |first=Paul |work=Video Business |deadurl=yes |archiveurl=https://web.archive.org/web/20060415091053/http://www.videobusiness.com/article/CA6300812.html |archivedate=15 April 2006 }}</ref>

AACS guidelines require that any title which implements the ICT must clearly state so on the packaging. The German magazine "Der Spiegel" has reported about an unofficial agreement between film studios and electronics manufacturers to not use ICT until 2010 – 2012.<ref>{{cite web |url=https://arstechnica.com/news.ars/post/20060521-6880.html |title=Hollywood reportedly in agreement to delay forced quality downgrades for Blu-ray, HD DVD |accessdate=2007-11-02 |author =Ken Fisher |date=21 May 2006 |work=arstechnica.com| archiveurl= https://web.archive.org/web/20071105063630/http://arstechnica.com/news.ars/post/20060521-6880.html| archivedate= 5 November 2007 <!--DASHBot-->| deadurl= no}}</ref> However, some titles have already been released that apply ICT.<ref>{{cite web |url=http://www.areadvd.de/news/2007/200710/29102007001_RE_HD_DVD.shtml |title=HD DVD: "Resident Evil" nur in Standard-Auflösung via YUV |accessdate=2007-11-02 |date=29 October 2007 |work=areadvd.de |language=German |deadurl=yes |archiveurl=https://web.archive.org/web/20080111071532/http://www.areadvd.de/news/2007/200710/29102007001_RE_HD_DVD.shtml |archivedate=11 January 2008 }}</ref>

=== Audio watermarking ===

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== History ==

On 24 February 2001, Dalit Naor, Moni Naor and Jeff Lotspiech published a paper entitled "Revocation and Tracing Schemes for Stateless Receivers", where they described a broadcast encryption scheme using a construct called Naor-Naor-Lotspiech subset-difference trees. That paper laid the theoretical foundations of AACS.<ref>{{cite web |url=http://www.playfuls.com/news_05648_HD_DVDs_AACS_Protection_Bypassed_In_Only_8_Days.html |title=HD DVD's AACS Protection Bypassed. In Only 8 Days?! |accessdate=2007-10-25 |author =Dan Nicolae Alexa |date=28 December 2006 |work=playfuls.com |deadurl=yes |archiveurl=https://web.archive.org/web/20080210005229/http://www.playfuls.com/news_05648_HD_DVDs_AACS_Protection_Bypassed_In_Only_8_Days.html |archivedate=10 February 2008 }}</ref>

The AACS LA consortium was founded in 2004.<ref>{{cite news |url=http://archive.wired.com/entertainment/music/news/2004/07/64212 |title=Can Odd Alliance Beat Pirates? |accessdate=2015-01-20 |author =Katie Dean |date=15 July 2004 |work=Wired }}</ref> With [[DeCSS]] in hindsight, the ''[[IEEE Spectrum]]'' magazine's readers voted AACS to be one of the technologies most likely to fail in the January 2005 issue.<ref>{{cite web

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|date=January 2007

| work = Spectrum Online| archiveurl= https://web.archive.org/web/20070608074811/http://spectrum.ieee.org/jan05/2703| archivedate= 8 June 2007 <!--DASHBot-->| deadurl= no}}</ref>

The final AACS standard was delayed,<ref>{{cite web |url=http://www.pcworld.com/article/id,123924-page,1/article.html |title=Toshiba Hints at HD-DVD Delay |accessdate=2007-10-19 |author =Martyn Williams |date=14 December 2005 |work=pcworld.com | archiveurl= https://web.archive.org/web/20071005171717/http://www.pcworld.com/article/id,123924%2C123924-page,1%2C1/article.html | archivedate= 5 October 2007 <!--DASHBot-->| deadurl=no no}}</ref> and then delayed again when an important member of the Blu-ray group voiced concerns.<ref>{{cite web |url=http://www.heise.de/english/newsticker/news/69559 |title=AACS copy protection for Blu-ray disc and HD DVD delayed again |accessdate=2007-10-19 |author =Craig Morris |date=14 February 2006 |work=heise.de | archiveurl= https://web.archive.org/web/20071102222432/http://www.heise.de/english/newsticker/news/69559| archivedate= 2 November 2007 <!--DASHBot-->| deadurl= no}}</ref> At the request of Toshiba, an interim standard was published which did not include some features, like managed copy.<ref name=pcworld-burning-questions /> As of 15 October 2007, the final AACS standard had not yet been released.<ref>{{cite web |url=http://www.contentagenda.com/article/CA6491476.html |title=AACS still trying to manage copying |accessdate=2007-10-25 |author =Paul Sweeting |date=15 October 2007 |work=contentagenda.com}}</ref>

==Unlicensed decryption==