Advanced Access Content System: Difference between revisions

Revision as of 18:09, 6 October 2019

Revision as of 17:30, 5 February 2020

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{{For|other AACS uses|AACS (disambiguation){{!}}AACS}}

{{Update|date=August 2017}}

{{Use dmy dates|date=AprilFebruary 20122020}}

[[Image:AACS dataflow.svg|right|thumb|AACS decryption process]]

{{For|other AACS uses|AACS (disambiguation){{!}}AACS}}

The '''Advanced Access Content System''' ('''AACS''') is a [[standardization|standard]] for [[content distribution]] and [[digital rights management]], intended to restrict access to and copying of the post-DVD generation of optical discs. The specification was publicly released in April 2005 and the standard has been adopted as the access restriction scheme for [[HD DVD]] and [[Blu-ray Disc]] (BD). It is developed by [[AACS LA|AACS Licensing Administrator, LLC]] (AACS LA), a [[consortium]] that includes [[The Walt Disney Company|Disney]], [[Intel]], [[Microsoft]], [[Panasonic Corporation|Panasonic]], [[Warner Bros.]], [[IBM]], [[Toshiba]] and [[Sony]]. AACS has been operating under an "interim agreement" since the final specification (including provisions for [[#Managed Copy|Managed Copy]]) has not yet been finalized.

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AACS also incorporates [[traitor tracing]] techniques. The standard allows for multiple versions of short sections of a movie to be encrypted with different keys, while a given player will only be able to decrypt one version of each section. The manufacturer embeds varying [[Digital watermarking|digital watermarks]] in these sections, and upon subsequent analysis of the pirated release the compromised keys can be identified and revoked (this feature is called ''Sequence keys'' in the AACS specifications).<ref>{{cite web

| author = Hongxia Jin |author2=Jeffery Lotspiech |author3-link=Nimrod Megiddo |author3=[[Nimrod Megiddo]]

| title = Efficient Traitor Tracing

|date=4 October 2006

| url = http://domino.watson.ibm.com/library/cyberdig.nsf/papers/AF8C220CB33D5A98852571FF00570458/$File/rj10390.pdf

| accessdate = 2 May 2007-05-02}}</ref>

<ref>{{cite web

|title = AACS Reference: Pre-recorded Video Book

|url = http://www.aacsla.com/specifications/specs091/AACS_Spec_Prerecorded_0.91.pdf

|accessdate = 2 May 2007-05-02

|archive-url = https://web.archive.org/web/20120206054929/http://www.aacsla.com/specifications/specs091/AACS_Spec_Prerecorded_0.91.pdf

|archive-date = 6 February 2012

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=== Volume IDs ===

Volume IDs are unique identifiers or serial numbers that are stored on pre-recorded discs with special hardware. They cannot be duplicated on consumers' recordable media. The point of this is to prevent simple bit-by-bit copies, since the Volume ID is required (though not sufficient) for decoding content. On Blu-ray discs, the Volume ID is stored in the [[ROM-Mark|BD-ROM Mark]].<ref>{{cite web |url=http://www.aacsla.com/specifications/AACS_Spec_BD_Prerecorded_0.912.pdf |title=Blu-ray Disc Pre-recorded Book |accessdate=1 November 2007-11-01 |date=27 July 2006 |publisher=AACS LA |page=15 |archiveurl=https://web.archive.org/web/20071106065659/http://www.aacsla.com/specifications/AACS_Spec_BD_Prerecorded_0.912.pdf |archivedate=6 November 2007 |url-status=dead |df=dmy-all }}</ref>

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=4 May 2007-05-04

|first=Jeremy

|last=Reimer

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

|title = Got VolumeID without AACS authentication :)

|accessdate = 4 May 2007-05-04

|author = Geremia

|date=4 April 2007

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|url = http://www.aacsla.com/specifications/specs091/AACS_Spec_Common_0.91.pdf

|title = Advanced Access Content System (AACS): Introduction and Common Cryptographic Elements

|accessdate = 5 June 2007-06-05

|date = 17 February 2007

|work = AACS Licensing Administrator

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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'down-converting’converting' forced |accessdate=4 May 2007-05-04 |date=19 January 2006 |last=Sweeting |first=Paul |work=Video Business |url-status=dead |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=2 November 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 | url-status= live}}</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=2 November 2007-11-02 |date=29 October 2007 |work=areadvd.de |language=German |url-status=dead |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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| url = http://www.hp.com/hpinfo/newsroom/press/2005/051216a.html

| title =HP to Support HD-DVD High-definition DVD Format and Join HD-DVD Promotions Group

| accessdate = 3 May 2007-05-03

| archiveurl= https://web.archive.org/web/20070504142655/http://www.hp.com/hpinfo/newsroom/press/2005/051216a.html| archivedate= 4 May 2007 | url-status= live}}</ref>

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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 October 2007 |author=Dan Nicolae Alexa |date=28 December 2006 |work=playfuls.com |url-status=dead |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 January 2015 |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

|url = http://www.spectrum.ieee.org/jan05/2703

|title = Loser: DVD Copy Protection, Take 2

|accessdate = 4 May 2007-05-04

|author = Tekla S. Perry

|date = January 2007

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|archivedate = 8 June 2007

|url-status = dead

|df = dmy-all

}}</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 October 2007 |author=Martyn Williams |date=14 December 2005 |work=pcworld.com |archiveurl=https://web.archive.org/web/20071005171717/http://www.pcworld.com/article/id%2C123924-page%2C1/article.html |archivedate=5 October 2007 |url-status=live }}</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 October 2007 |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 | url-status= live}}</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 October 2007 |author =Paul Sweeting |date=15 October 2007 |work=contentagenda.com}}</ref>

==Unlicensed decryption==

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| last = Drawbaugh

| title = BackupBluray available now too

| accessdate = 3 May 2007-05-03

|date=24 January 2007

| work = Engadget| archiveurl= https://web.archive.org/web/20070516060453/http://www.engadget.com/2007/01/24/backupbluray-available-now-too/| archivedate= 16 May 2007 | url-status= live}}</ref> Blu-ray Copy is a program capable of copying Blu-rays to the [[hard drive]] or to blank BD-R discs.<ref>{{cite news|title=Get Blu-ray Copy (Win) for free|url=http://reviews.cnet.com/8301-33153_7-57468788-10391733/get-blu-ray-copy-win-for-free/|first=Rick|last=Broida|date=July 9, July 2012|work=[[CNET]]|accessdate=2013-07-18 July 2013}}</ref>

==Security==

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| work = TechAmok

|date=28 December 2006

| accessdate = 2 January 2007-01-02 }}</ref><ref>{{cite news

| url = http://news.bbc.co.uk/2/hi/technology/6301301.stm

| title = Hi-def DVD security is bypassed

|date=26 January 2007

|accessdate=2 May 2007-05-02

|work=BBC news| archiveurl= https://web.archive.org/web/20070505121314/http://news.bbc.co.uk/2/hi/technology/6301301.stm| archivedate= 5 May 2007 | url-status= live}}</ref>

<ref>{{cite web

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| title = Blu-ray cracked too?

|date=20 January 2007

| accessdate = 2007-01-22 January 2007

|work=Engadget | archiveurl= https://web.archive.org/web/20070123114257/http://www.engadget.com/2007/01/20/blu-ray-cracked-too/| archivedate= 23 January 2007 | url-status= live}}</ref>

<ref>{{cite web

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| title = Blu-ray DRM defeated

|date=23 January 2007

| accessdate = 2007-01-22 January 2007| archiveurl= https://web.archive.org/web/20070125175901/https://www.theregister.co.uk/2007/01/23/blu-ray_drm_cracked/| archivedate= 25 January 2007 | url-status= live}}</ref>

Hackers also claim to have found Device Keys<ref>{{cite web

|url=http://forum.doom9.org/showthread.php?t=122664

|title=WinDVD 8 Device Key Found!

|accessdate=4 May 2007-05-04

|author ="ATARI Vampire"

|date=24 February 2007

|work=Doom9.net forums}}</ref>

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|url=http://forum.doom9.org/showthread.php?t=122969

|title=PowerDVD private key

|accessdate=4 May 2007-05-04

|author ="jx6bpm"

|date=3 March 2007

|work=Doom9.net forums| archiveurl= https://web.archive.org/web/20070329033807/http://forum.doom9.org/showthread.php?t=122969| archivedate= 29 March 2007 | url-status= live}}</ref>

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|url=http://www.dailytech.com/article.aspx?newsid=5747

|title=First Pirated HD DVDs Released

|accessdate=3 May 2007-05-03

|first=Marcus

|last=Yam

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|archive-date=19 February 2007

|url-status=dead

|df=dmy-all

}}

</ref>

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|url=http://www.chillingeffects.org/notice.cgi?sID=3218

|title=AACS licensor complains of posted key

|accessdate=2 May 2007-05-02<!--DASHBot-->}}</ref>

Some sites that rely on user-submitted content, like [[Digg]] and Wikipedia, tried to remove any mentions of the key.<ref>{{cite news

|url=http://blog.wired.com/business/2007/05/wikipedia_locks.html

|title Locks Out "The Number"

|title=Wikipedia Locks Out "The Number"

|first=Paul

|last=Boutin

|accessdate=2 May 2007-05-02

|date=1 May 2007

|work=Wired| archiveurl= https://web.archive.org/web/20070504012402/http://blog.wired.com/business/2007/05/wikipedia_locks.html| archivedate= 4 May 2007 | url-status= live}}</ref>

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|work=Forbes

|url=https://www.forbes.com/technology/2007/05/02/digital-rights-management-tech-cx_ag_0502digg.html

|accessdate=4 May 2007-05-04| archiveurl= https://web.archive.org/web/20070504173353/http://www.forbes.com/technology/2007/05/02/digital-rights-management-tech-cx_ag_0502digg.html| archivedate= 4 May 2007 | url-status= live}}</ref>

The Digg administrators eventually gave up trying to censor submissions that contained the key.<ref>{{cite news

|url=http://news.bbc.co.uk/2/hi/technology/6615047.stm

|title=DVD DRM row sparks user rebellion

|accessdate = 2 May 2007-05-02

|date=2 May 2007

|work=BBC news| archiveurl= https://web.archive.org/web/20070516215800/http://news.bbc.co.uk/2/hi/technology/6615047.stm| archivedate= 16 May 2007 | url-status= live}}</ref>

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On 16 April 2007, the AACS consortium announced that it had expired certain encryption keys used by PC-based applications. Patches were available for WinDVD and PowerDVD which used new and uncompromised encryption keys.<ref>

{{cite web| url= http://www.aacsla.com/press/| title= Press Messages: AACS – Advanced Access Content System| accessdate= 2 May 2007-05-02| archiveurl= https://web.archive.org/web/20070430070403/http://www.aacsla.com/press/| archivedate= 30 April 2007| url-status= dead| df= dmy-all}}

</ref>

<ref>

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|url=http://dailytech.com/AACS+Responds+to+Cracked+HD+DVD+and+Bluray+Disc+Protections/article5879.htm

|title=AACS Responds to Cracked HD DVD and Blu-ray Disc Protections

|accessdate=3 May 2007-05-03

|first=Marcus

|last=Yam

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|archive-date=11 February 2007

|url-status=dead

|df=dmy-all

}}

</ref>

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|url=http://www.newsfactor.com/news/Blu-ray--HD-DVD-Encryption-Cracked/story.xhtml?story_id=121000E3UUOA

|title=Blu-ray and HD DVD Encryption Cracked

|accessdate=2007-05-29 May 2007

|author=Lindsay Martell

|date=26 January 2007

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|archive-date=3 November 2007

|url-status=dead

|df=dmy-all

}}

</ref>

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|title=Illegal Offering of Title/Volume Keys to Circumvent AACS Copyright Protection: hdkeys.com

|format=pdf

|accessdate=2007-05-29 May 2007

|author =Alexander Kaplan

|date=5 April 2007

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|url=https://arstechnica.com/news.ars/post/20070517-latest-aacs-revision-defeated-a-week-before-release.html

|title=Latest AACS revision defeated a week before release

|accessdate=2007-05-29 May 2007

|author =Ryan Paul

|date=7 May 2007

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| title = Work Around for New DVD Format Protections

|date=7 June 2006

| accessdate = 2 May 2007-05-02

| work = [[Slashdot]]}}</ref><ref>{{cite web

| url = http://www.heise-online.co.uk/security/Copy-protection-hole-in-Blu-ray-and-HD-DVD-movies--/news/75103

| archiveurl = https://web.archive.org/web/20080222160135/http://www.heise-online.co.uk/security/Copy-protection-hole-in-Blu-ray-and-HD-DVD-movies--/news/75103

| title = Copy protection hole in Blu-ray and HD DVD movies

| accessdate = 2 May 2007-05-02

| archivedate = 22 February 2008

|date=7 July 2006

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|url=http://www.google.com/patents?id=rNoOAAAAEBAJ&dq=6,563,928

|title=Strengthened public key protocol

|accessdate=2007-05-31 May 2007

|author =Scott A. Vanstone

|date=1 April 1999

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|url=http://www.google.com/patents?id=rZ0SAAAAEBAJ&dq=6704870

|title=Digital signatures on a Smartcard

|accessdate=2007-05-31 May 2007

|author =Scott A. Vanstone

|date=29 August 2001

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|url=https://arstechnica.com/news.ars/post/20070531-encryption-vendor-claims-aacs-infringes-its-patents-sues-sony.html

|title=Encryption vendor claims AACS infringes its patents, sues Sony

|accessdate=2007-05-31 May 2007

|author =Nate Anderson

|date=31 May 2007

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==References==

{{reflist|colwidth=30em}}

==External links==