Digital rights management: Difference between revisions

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==DRM in video content==

Attempting to prevent the copying of video content is one of the most common and long-standing uses of DRM. The idea of using copy obstruction on video content predates the term "DRM", one early example being the "Automatic Gain Control" requirement in VCRs used to enforce the "Macrovision" copy-protection scheme.<ref>{{Cite web |date=1999-11-29 |title=17 U.S. Code § 1201 - Circumvention of copyright protection systems |url=https://www.law.cornell.edu/uscode/text/17/1201#k_1_A |url-status=live |archive-url=https://web.archive.org/web/20260201101756/https://www.law.cornell.edu/uscode/text/17/1201#k_1_A |archive-date=2026-02-01 |access-date=2026-02-06 |website=Cornell Law School}}</ref><ref>{{Cite web |date=2018 |title=Macrovision Demystified |url=https://cs.stanford.edu/people/eroberts/courses/cs181/projects/1999-00/dmca-2k/macrovision.html |url-status=live |archive-url=https://web.archive.org/web/20251212001352/https://cs.stanford.edu/people/eroberts/courses/cs181/projects/1999-00/dmca-2k/macrovision.html |archive-date=2025-12-12 |access-date=2026-02-06 |website=Stanford Engineering Computer Science}} </ref> ~~This requirement resulted in VCRs and compliant analog to DV capture cards not being able to record commercial VHS tapes~~{{~~citation needed~~}}.

Attempting to prevent the copying of video content is one of the most common and long-standing uses of DRM. The idea of using copy obstruction on video content predates the term "DRM", one early example being the "Automatic Gain Control" requirement in VCRs used to enforce the "Macrovision" copy-protection scheme.<ref>{{Cite web |date=1999-11-29 |title=17 U.S. Code § 1201 - Circumvention of copyright protection systems |url=https://www.law.cornell.edu/uscode/text/17/1201#k_1_A |url-status=live |archive-url=https://web.archive.org/web/20260201101756/https://www.law.cornell.edu/uscode/text/17/1201#k_1_A |archive-date=2026-02-01 |access-date=2026-02-06 |website=Cornell Law School}}</ref><ref>{{Cite web |date=2018 |title=Macrovision Demystified |url=https://cs.stanford.edu/people/eroberts/courses/cs181/projects/1999-00/dmca-2k/macrovision.html |url-status=live |archive-url=https://web.archive.org/web/20251212001352/https://cs.stanford.edu/people/eroberts/courses/cs181/projects/1999-00/dmca-2k/macrovision.html |archive-date=2025-12-12 |access-date=2026-02-06 |website=Stanford Engineering Computer Science}} </ref>

Formally known as "Analog Copy Protection", the scheme worked by encoding specific control signals into the output signal that corrupted the video. <ref name="hackaday_article">

{{Cite web

| last = Maloney

| first = Dan

| date = 2018-05-27

| title = Rolling Old School With Copy Protection From The 1980s

| url = https://hackaday.com/2018/05/27/rolling-old-school-with-copy-protection-from-the-1980s/

| access-date = 2026-03-19

| archive-url = https://ghostarchive.org/archive/wa2zi

| archive-date = 2026-03-19

}}

</ref>

These signals were generally ignored by TVs, so when the VHS tape was played back, the video appeared correct, but VCRs handled these bogus signals, causing the recorded tape to contain the corrupted video. <ref name="hackaday_article" />

From 1996, DVDs began to feature the "Content Scramble System" (CSS), an encryption based DRM. CSS was successfully circumvented as early as 1999, less than five years after its introduction, partly due to the limited length of the 40-bit encryption key, which was used to comply with US government export regulations of the time.<ref>{{Cite web |last=Stevenson |first=Frank Andrew |date=27 Oct 1999 |title=[Livid-dev] Successfull attack on CSS algorithm |url=https://www.cs.cmu.edu/~dst/DeCSS/FrankStevenson/mail1.txt |url-status=live |archive-url=https://web.archive.org/web/20260114031245/https://www.cs.cmu.edu/~dst/DeCSS/FrankStevenson/mail1.txt |archive-date=2026-01-14 |access-date=2026-02-06 |website=Carnegie Mellon University School of Computer Science}}</ref><ref>{{Cite web |last=Stevenson |first=Frank A. |date=8 November 1999 |title=Cryptanalysis of Contents Scrambling System |url=http://www.dvd-copy.com/news/cryptanalysis_of_contents_scrambling_system.htm |url-status=dead |archive-url=https://web.archive.org/web/20000302000206/http://www.dvd-copy.com/news/cryptanalysis_of_contents_scrambling_system.htm |archive-date=2000-03-02 |access-date=2026-02-06 |website=DVD-Copy}}</ref> Following this, DVDs as well as HD-DVDs and Blu-Rays would implement other types of DRM, one of them being the "Advanced Access Content System".<ref>{{Cite web |title=Advanced Access Content System (AACS) |url=https://www.aacsla.com/specifications/specs091/AACS_Spec_Common_0.91.pdf |url-status=dead |archive-url=https://web.archive.org/web/20070302130221/http://www.aacsla.com/specifications/specs091/AACS_Spec_Common_0.91.pdf |archive-date=2 Mar 2007 |access-date=20 Apr 2025}}

@@ Line 36: / Line 36: @@
 ==DRM in video content==
-Attempting to prevent the copying of video content is one of the most common and long-standing uses of DRM. The idea of using copy obstruction on video content predates the term "DRM", one early example being the "Automatic Gain Control" requirement in VCRs used to enforce the "Macrovision" copy-protection scheme.<ref>{{Cite web |date=1999-11-29 |title=17 U.S. Code § 1201 - Circumvention of copyright protection systems |url=https://www.law.cornell.edu/uscode/text/17/1201#k_1_A |url-status=live |archive-url=https://web.archive.org/web/20260201101756/https://www.law.cornell.edu/uscode/text/17/1201#k_1_A |archive-date=2026-02-01 |access-date=2026-02-06 |website=Cornell Law School}}</ref><ref>{{Cite web |date=2018 |title=Macrovision Demystified |url=https://cs.stanford.edu/people/eroberts/courses/cs181/projects/1999-00/dmca-2k/macrovision.html |url-status=live |archive-url=https://web.archive.org/web/20251212001352/https://cs.stanford.edu/people/eroberts/courses/cs181/projects/1999-00/dmca-2k/macrovision.html |archive-date=2025-12-12 |access-date=2026-02-06 |website=Stanford Engineering Computer Science}} </ref> This requirement resulted in VCRs and compliant analog to DV capture cards not being able to record commercial VHS tapes{{citation needed}}.
+Attempting to prevent the copying of video content is one of the most common and long-standing uses of DRM. The idea of using copy obstruction on video content predates the term "DRM", one early example being the "Automatic Gain Control" requirement in VCRs used to enforce the "Macrovision" copy-protection scheme.<ref>{{Cite web |date=1999-11-29 |title=17 U.S. Code § 1201 - Circumvention of copyright protection systems |url=https://www.law.cornell.edu/uscode/text/17/1201#k_1_A |url-status=live |archive-url=https://web.archive.org/web/20260201101756/https://www.law.cornell.edu/uscode/text/17/1201#k_1_A |archive-date=2026-02-01 |access-date=2026-02-06 |website=Cornell Law School}}</ref><ref>{{Cite web |date=2018 |title=Macrovision Demystified |url=https://cs.stanford.edu/people/eroberts/courses/cs181/projects/1999-00/dmca-2k/macrovision.html |url-status=live |archive-url=https://web.archive.org/web/20251212001352/https://cs.stanford.edu/people/eroberts/courses/cs181/projects/1999-00/dmca-2k/macrovision.html |archive-date=2025-12-12 |access-date=2026-02-06 |website=Stanford Engineering Computer Science}} </ref>
+Formally known as "Analog Copy Protection", the scheme worked by encoding specific control signals into the output signal that corrupted the video. <ref name="hackaday_article">
+{{Cite web
+| last = Maloney
+| first = Dan
+| date = 2018-05-27
+| title = Rolling Old School With Copy Protection From The 1980s
+| url = https://hackaday.com/2018/05/27/rolling-old-school-with-copy-protection-from-the-1980s/
+| access-date = 2026-03-19
+| archive-url = https://ghostarchive.org/archive/wa2zi
+| archive-date = 2026-03-19
+}}
+</ref>
+These signals were generally ignored by TVs, so when the VHS tape was played back, the video appeared correct, but VCRs handled these bogus signals, causing the recorded tape to contain the corrupted video. <ref name="hackaday_article" />
 From 1996, DVDs began to feature the "Content Scramble System" (CSS), an encryption based DRM. CSS was successfully circumvented as early as 1999, less than five years after its introduction, partly due to the limited length of the 40-bit encryption key, which was used to comply with US government export regulations of the time.<ref>{{Cite web |last=Stevenson |first=Frank Andrew |date=27 Oct 1999 |title=[Livid-dev] Successfull attack on CSS algorithm |url=https://www.cs.cmu.edu/~dst/DeCSS/FrankStevenson/mail1.txt |url-status=live |archive-url=https://web.archive.org/web/20260114031245/https://www.cs.cmu.edu/~dst/DeCSS/FrankStevenson/mail1.txt |archive-date=2026-01-14 |access-date=2026-02-06 |website=Carnegie Mellon University School of Computer Science}}</ref><ref>{{Cite web |last=Stevenson |first=Frank A. |date=8 November 1999 |title=Cryptanalysis of Contents Scrambling System |url=http://www.dvd-copy.com/news/cryptanalysis_of_contents_scrambling_system.htm |url-status=dead |archive-url=https://web.archive.org/web/20000302000206/http://www.dvd-copy.com/news/cryptanalysis_of_contents_scrambling_system.htm |archive-date=2000-03-02 |access-date=2026-02-06 |website=DVD-Copy}}</ref> Following this, DVDs as well as HD-DVDs and Blu-Rays would implement other types of DRM, one of them being the "Advanced Access Content System".<ref>{{Cite web |title=Advanced Access Content System (AACS) |url=https://www.aacsla.com/specifications/specs091/AACS_Spec_Common_0.91.pdf |url-status=dead |archive-url=https://web.archive.org/web/20070302130221/http://www.aacsla.com/specifications/specs091/AACS_Spec_Common_0.91.pdf |archive-date=2 Mar 2007 |access-date=20 Apr 2025}}