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Copy protection, also known as content protection, copy prevention and copy restriction, describes measures to enforce copyright by preventing the reproduction of software, films, music, and other media.[1]

Copy protection is most commonly found on videotapes, DVDs, Blu-ray discs, HD-DVDs, computer software discs, video game discs and cartridges, audio CDs and some VCDs.

Some methods of copy protection have also led to criticism because it caused inconvenience for paying consumers or secretly installed additional or unwanted software to detect copying activities on the consumer's computer. Making copy protection effective while protecting consumer rights remains a problem with media publication.


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Media corporations have always used the term copy protection, but critics argue that the term tends to sway the public into identifying with the publishers, who favor restriction technologies, rather than with the users.[2] Copy prevention and copy control may be more neutral terms. "Copy protection" is a misnomer for some systems, because any number of copies can be made from an original and all of these copies will work, but only in one computer, or only with one dongle, or only with another device that cannot be easily copied.

The term is also often related to, and confused with, the concept of digital rights management. Digital rights management is a more general term because it includes all sorts of management of works, including copy restrictions. Copy protection may include measures that are not digital. A more appropriate term may be "technological protection measures" (TPMs),[3] which is often defined as the use of technological tools in order to restrict the use or access to a work.

Business rationale

Unauthorized copying and distribution accounted for $2.4 billion per year in lost revenue in the United States alone in 1990,[4] and is assumed to be causing impact on revenues in the music and the video game industry, leading to proposal of stricter copyright laws such as PIPA.

Copy protection is most commonly found on videotapes, DVDs, computer software discs, video game discs and cartridges, audio CDs and some VCDs.

Many media formats are easy to copy using a machine, allowing consumers to distribute copies to their friends, a practice known as "casual copying".

Companies publish works under copyright protection because they believe that the cost of implementing the copy protection will be less than the revenue produced by consumers who buy the product instead of acquiring it through casually copied media.

Opponents of copy protection argue that people who obtain free copies only use what they can get for free and would not purchase their own copy if they were unable to obtain a free copy. Some even argue that free copies increase profit; people who receive a free copy of a music CD may then go and buy more of that band's music, which they would not have done otherwise.

Some publishers have avoided copy-protecting their products on the theory that the resulting inconvenience to their users outweighs any benefit of frustrating "casual copying".

From the perspective of the end user, copy protection is always a cost. DRM and license managers sometimes fail, are inconvenient to use, and may not afford the user all of the legal use of the product they have purchased.

The term copy protection refers to the technology used to attempt to frustrate copying, and not to the legal remedies available to publishers or authors whose copyrights are violated. Software usage models range from node locking to floating licenses (where a fixed number licenses can be concurrently used across an enterprise), grid computing (where multiple computers function as one unit and so use a common license) and electronic licensing (where features can be purchased and activated online). The term license management refers to broad platforms which enable the specification, enforcement and tracking of software licenses. To safeguard copy protection and license management technologies themselves against tampering and hacking, software anti-tamper methods are used.

Floating licenses are also being referred to as Indirect Licenses, and are licenses that at the time they are issued, there is no actually user who will use them. That has some technical influence over some of their characteristics. Direct Licenses are issued after a certain user requires it. As an example, an activated Microsoft product, contains a Direct License which is locked to the PC where the product is installed.

From business standpoint, on the other hand, some services now try to monetize on additional services other than the media content so users can have better experience than simply obtaining the copied product.[5]

Technical challenges

From a technical standpoint, it seems impossible to completely prevent users from making copies of the media they purchase, as long as a "writer" is available that can write to blank media. All types of media require a "player"—a CD player, DVD player, videotape player, computer or video game console—which must be able to read the media in order to display it to a human. Logically, a player could be built that reads the media and then writes an exact copy of what was read to the same type of media.

At a minimum, digital copy protection of non-interactive works is subject to the analog hole: regardless of any digital restrictions, if music can be heard by the human ear, it can also be recorded (at the very least, with a microphone and tape recorder); if a film can be viewed by the human eye, it can also be recorded (at the very least, with a video camera and recorder). In practice, almost-perfect copies can typically be made by tapping into the analog output of a player (e.g. the speaker output or headphone jacks) and, once redigitized into an unprotected form, duplicated indefinitely. Copying text-based content in this way is more tedious, but the same principle applies: if it can be printed or displayed, it can also be scanned and OCRed. With basic software and some patience, these techniques can be applied by a typical computer-literate user.

Since these basic technical facts exist, it follows that a determined individual will definitely succeed in copying any media, given enough time and resources. Media publishers understand this; copy protection is not intended to stop professional operations involved in the unauthorized mass duplication of media, but rather to stop "casual copying".

Copying of information goods which are downloaded (rather than being mass-duplicated as with physical media) can be inexpensively customized for each download, and thus restricted more effectively, in a process known as "traitor tracing". They can be encrypted in a fashion which is unique for each user's computer, and the decryption system can be made tamper-resistant.


For information on individual protection schemes and technologies, see List of copy protection schemes or relevant category page.

Computer software

Copy protection for computer software, especially for games, has been a long cat-and-mouse struggle between publishers and crackers. These were (and are) programmers who defeated copy protection on software as a hobby, add their alias to the title screen, and then distribute the "cracked" product to the network of warez BBSes or Internet sites that specialized in distributing unauthorized copies of software.

Early ages

Further information: Bad sector § Copy protection

When computer software was still distributed in audio cassettes, audio copying was unreliable, while digital copying was time consuming. Software prices were comparable with audio cassette prices.[4][6] To make digital copying more difficult, many programs used non-standard loading methods (loaders incompatible with standard BASIC loaders, or loaders that used different transfer speed).

Unauthorized software copying began to be a problem when floppy disks became the common storage media.[6] The ease of copying depended on the system; Jerry Pournelle wrote in BYTE in 1983 that "CP/M doesn't lend itself to copy protection" so its users "haven't been too worried" about it, while "Apple users, though, have always had the problem. So have those who used TRS-DOS, and I understand that MS-DOS has copy protection features".[7]

1980s Locksmith

Pournelle disliked copy protection[8] and, except for games, refused to review software that used it. He did not believe that it was useful, writing in 1983 that "For every copy protection scheme there's a hacker ready to defeat it. Most involve so-called nibble/nybble copiers, which try to analyze the original disk and then make a copy".[7] IBM's Don Estridge agreed: "I guarantee that whatever scheme you come up with will take less time to break than to think of it." While calling piracy "a threat to software development. It's going to dry up the software", he said "It's wrong to copy-protect programs ... There ought to be some way to stop [piracy] without creating products that are unusable."[9] Copy protection sometimes caused software not to run on clones, such as the Apple II-compatible Laser 128,[10] or even the genuine Commodore 64 with certain peripherals.[11]

In 1989 Gilman Louie, head of Spectrum Holobyte, stated that copy protection added about $0.50 per copy to the cost of production of a game.[12] Other software relied on complexity; Antic in 1988 observed that WordPerfect for the Atari ST "is almost unusable without its manual of over 600 pages!".[13] (The magazine was mistaken; the ST version was so widely pirated that the company threatened to discontinue it.[14][15])

To limit reusing activation keys to install the software on multiple machines, it has been attempted to tie the installed software to a specific machine by involving some unique feature of the machine. Serial number in ROM could not be used because some machines do not have them. Some popular surrogate for a machine serial number were date and time (to the second) of initialization of the hard disk or MAC address of Ethernet cards (although this is programmable on modern cards). With the rise of virtualization, however, the practice of locking has to add to these simple hardware parameters to still prevent copying.[16]

Early video games

During the 1980s and 1990s, video games sold on audio cassette and floppy disks were sometimes protected with an external user-interactive method that demanded the user to have the original package or a part of it, usually the manual. Copy protection was activated not only at installation, but every time the game was executed.[17][18]

Several imaginative and creative methods have been employed, in order to be both fun and hard to copy. These include:[19]

All of these methods proved to be troublesome and tiring for the players, and as such greatly declined in usage by the mid-1990s, at which point the emergence of CDs as the primary video game medium made copy protection largely redundant, since CD copying technology was not widely available at the time.[17]

Some game developers, such as Markus Persson,[23] have encouraged consumers and other developers to embrace the reality of unlicensed copying and utilize it positively to generate increased sales and marketing interest.


Starting in 1985 with the video release of The Cotton Club (Beta and VHS versions only), Macrovision licensed to publishers a technology that exploits the automatic gain control feature of VCRs by adding pulses to the vertical blanking sync signal.[24] These pulses may negatively affect picture quality, but succeed in confusing the recording-level circuitry of many consumer VCRs. This technology, which is aided by U.S. legislation mandating the presence of automatic gain-control circuitry in VCRs, is said to "plug the analog hole" and make VCR-to-VCR copies impossible, although an inexpensive circuit is widely available that will defeat the protection by removing the pulses. Macrovision had patented methods of defeating copy prevention,[25] giving it a more straightforward basis to shut down manufacture of any device that descrambles it than often exists in the DRM world. While used for pre-recorded tapes, the system was not adopted for television broadcasts; Michael J. Fuchs of HBO said in 1985 that Macrovision was "not good technology" because it reduced picture quality and consumers could easily bypass it, while Peter Chernin of Showtime said "we want to accommodate our subscribers and we know they like to tape our movies".[26]

Notable payloads

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Over time, software publishers (especially in the case of video games) became creative about crippling the software in case it was duplicated. These games would initially show that the copy was successful, but eventually render themselves unplayable via subtle methods. Many games use the "code checksumming" technique to prevent alteration of code to bypass other copy protection. Important constants for the game - such as the accuracy of the player's firing, the speed of their movement, etc. - are not included in the game but calculated from the numbers making up the machine code of other parts of the game. If the code is changed, the calculation yields a result which no longer matches the original design of the game and the game plays improperly.

Copying commercial games, such as this one, is a criminal offense and copyright infringement.

Copying and re-supplying games such as this one can lead to a term of imprisonment.
Think of a pirated game as stolen property.
This game is protected by the FADE system. You can play with a pirated game- but not for long. The quality of a pirated game will degrade over time.

Purchase only genuine software at legitimate stores.

The usage of copy protection payloads which lower playability of a game without making it clear that this is a result of copy protection is now generally considered unwise, due to the potential for it to result in unaware players with unlicensed copies spreading word-of-mouth that a game is of low quality. The authors of FADE explicitly acknowledged this as a reason for including the explicit warning message.


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Anti-piracy measures are efforts to fight against copyright infringement, counterfeiting, and other violations of intellectual property laws.

It includes, but is by no means limited to, the combined efforts of corporate associations (such as the RIAA and MPAA), law enforcement agencies (such as the FBI and Interpol), and various international governments[clarification needed] to combat copyright infringement relating to various types of creative works, such as software, music and films. These measures often come in the form of copy protection measures such as DRM, or measures implemented through a content protection network, such as Distil Networks or Incapsula. Richard Stallman and the GNU Project have criticized the use of the word "piracy" in these situations, saying that publishers use the word to refer to "copying they don't approve of" and that "they [publishers] imply that it is ethically equivalent to attacking ships on the high seas, kidnapping and murdering the people on them".[37] Certain forms of Anti-Piracy (such as DRM), are considered by consumers to control the use of the products content after sale.

In the case MPAA v. Hotfile, Judge Kathleen M. Williams granted a motion to deny the prosecution the usage of words she views as "pejorative". This list included the word "piracy", the use of which, the motion by the defense stated, would serve no purpose but to misguide and inflame the jury. The plaintiff argued the common use of the terms when referring to copyright infringement should invalidate the motion, but the Judge did not concur.[38]

Anti-piracy in file sharing

Today copyright infringement is often facilitated by the use of file sharing. In fact, infringement accounts for 23.8% of all internet traffic in 2013.[39] In an effort to cut down on this, both large and small films and music corporations have issued DMCA takedown notices, filed lawsuits, and pressed criminal prosecution of those who host these file sharing services.[40][41][42][43]

See also


  1. ^ Thomas Obnigene, DVD Glossary Archived 2020-08-15 at the Wayback Machine, 2007. Retrieved 19 July 2007.
  2. ^ Confusing Words and Phrases that are Worth Avoiding Archived 2013-06-03 at the Wayback Machine, GNU Project - Free Software Foundation (FSF).
  3. ^ How do technological protection measures work? Archived 14 June 2013 at the Wayback Machine, World Intellectual Property Organization
  4. ^ a b Greg Short, Comment, Combatting Software Piracy: Can Felony Penalties for Copyright Infringement Curtail the Copying of Computer Software?, 10 Santa Clara Computer & High Tech. L.J. 221 (1994). Available at: Archived 2021-01-16 at the Wayback Machine
  5. ^ Wallach, D.S. (Oct 2011). "Copy protection technology is doomed". Computer. 34 (10): 48–49. doi:10.1109/2.955098.
  6. ^ a b Copy Protection: A History and Outlook Archived 2009-12-13 at the Wayback Machine
  7. ^ a b Pournelle, Jerry (June 1983). "Zenith Z-100, Epson QX-10, Software Licensing, and the Software Piracy Problem". BYTE. p. 411. Retrieved 20 October 2013.
  8. ^ Riley, John (1985-10-27). "LORD OF CHAOS MANOR : Hoping for a message from a long-lost friend". Los Angeles Times. Archived from the original on 2021-05-22. Retrieved 2021-05-22.
  9. ^ Curran, Lawrence J.; Shuford, Richard S. (November 1983). "IBM's Estridge". BYTE. pp. 88–97. Retrieved 19 March 2016.
  10. ^ Mace, Scott (13 January 1986). "Two Firms Plan to Sell Apple Clone". InfoWorld. Archived from the original on 14 August 2021. Retrieved 16 October 2020.
  11. ^ Bobo, Ervin (February 1988). "Project: Stealth Fighter". Compute!. p. 51. Retrieved 10 November 2013.
  12. ^ Louie, Gilman (April 1989). "Low Shelf 'ST'eem". Computer Gaming World (letter). p. 4.
  13. ^ Pearlman, Gregg (May 1988). "WordPerfect ST / Proving why it's the IBM PC best seller". Antic. Vol. 7, no. 1. Archived from the original on 2016-12-22. Retrieved 2016-12-22.
  14. ^ "Word Perfect Furor". Archived from the original on 2016-12-22. Retrieved 2016-12-22.
  15. ^ "ST USER". Archived from the original on 2016-04-26. Retrieved 2016-12-22.
  16. ^ Dominic Haigh (28 June 2010). "Copy protection on virtual systems". Archived from the original on 8 June 2010. Retrieved 6 December 2010.
  17. ^ a b "The Next Generation 1996 Lexicon A to Z: Copy Protection". Next Generation. No. 15. Imagine Media. March 1996. p. 32.
  18. ^ Retro Gamer issue 83, "Don't copy that floppy"
  19. ^ Kelly, Andy (4 August 2020). "Code wheels, poison, and star maps: the creative ways old games fought piracy". PC Gamer. Archived from the original on 19 September 2020. Retrieved 4 August 2020.
  20. ^ "Copy Protection in Jet Set Willy: developing methodology for retrogame archaeology". Archived from the original on 29 January 2019. Retrieved 30 January 2019.
  21. ^ Barter, Pavel (August 22, 2007). "Protect and Serve". Gamesradar. Future US. Archived from the original on January 7, 2021. Retrieved January 7, 2021.
  22. ^ Whitehead, Dan (April 15, 2010). "Banging the DRM • Page 2". Eurogamer. Gamer Network. Archived from the original on June 4, 2010.
  23. ^ Thier, Dave. "Minecraft Creator Notch Tells Players to Pirate His Game". Forbes. Archived from the original on 2020-11-06. Retrieved 2020-09-25.
  24. ^ Some relevant patents are U.S. Patent 4,631,603; U.S. Patent 4,577,216; U.S. Patent 4,819,098; and U.S. Patent 4,907,093.
  25. ^ One such patent is U.S. Patent 5,625,691.
  26. ^ Holsopple, Barbara (5 June 1985). "Pay-TV looks elsewhere as theatrical movies lose their appeal". The Pittsburgh Press. pp. C12. Archived from the original on 5 May 2021. Retrieved 25 January 2015.
  27. ^ Sven Liebich, Germany. "". Archived from the original on 4 March 2001. Retrieved 6 December 2010.
  28. ^ "FADE Game Copy Protections". GameBurnWorld. Archived from the original on 19 February 2012. Retrieved 6 December 2010.
  29. ^ "Bohemia Interactive Details Unique Anti-Piracy Methods". GamePolitics. Archived from the original on 2012-03-15. Retrieved 2011-11-10.
  30. ^ "". 9 September 2009. Archived from the original on 8 February 2010. Retrieved 6 December 2010.
  31. ^ "MOTHER 2 / EarthBound Anti-Piracy Measures". Starmen.Net. Archived from the original on 9 February 2011. Retrieved 6 December 2010.
  32. ^ "Beejive IM Moves To Block Out iPhone Pirates". 19 March 2009. Archived from the original on 8 November 2012. Retrieved 6 December 2010.
  33. ^ Dodd, Gavin (17 October 2001). "Keeping the Pirates at Bay: Implementing Crack Protection for Spyro: Year of the Dragon". Gamasutra. Archived from the original on 26 March 2008. Retrieved 28 March 2008.
  34. ^ Walker, John (7 December 2011). "Serious Sam's DRM Is A Giant Pink Scorpion". Rock Paper Shotgun. Archived from the original on 8 December 2011. Retrieved 8 December 2011.
  35. ^ Patrick (29 April 2013). "What happens when pirates play a game development simulator and then go bankrupt because of piracy?". Archived from the original on 17 May 2021. Retrieved 30 April 2013.
  36. ^ Ernesto (29 April 2013). "Game Pirates Whine About Piracy in Game Dev Simulator". TorrentFreak. Archived from the original on 8 August 2014. Retrieved 27 July 2014.
  37. ^ Stallman, Richard. "Confusing Words and Phrases That Are Worth Avoiding". Free Software, Free Society: The Selected Essays of Richard M. Stallman. GNU Press. Archived from the original on 31 May 2010. Retrieved 1 June 2010.
  38. ^ "MPAA Banned From Using Piracy and Theft Terms in Hotfile Trial". Archived from the original on 30 November 2013. Retrieved 30 November 2013.
  39. ^ Boorstin, Julia (31 January 2011). "Piracy Rules the Web, Dominating 23.8% of Internet Traffic". CNBC Media Money. Archived from the original on 27 February 2021. Retrieved 28 May 2013.
  40. ^ Masnick, Mike (29 May 2012). "Fox Issues DMCA Takedown To Google Over SF Chronicle Article... Claiming It Was The Movie 'Chronicle'". Techdirt. Archived from the original on 12 November 2020. Retrieved 28 May 2013.
  41. ^ Menta, Rich. "RIAA Sues Music Startup Napster for $20 Billion". MP3Newswire. Archived from the original on 27 June 2017. Retrieved 28 May 2013.
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  43. ^ Boorstin, julia (6 February 2013). "The Weakest Link". The Hindu. Chennai, India. Archived from the original on 2 April 2016. Retrieved 26 July 2013.