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Copy Protection

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'''Copy protection''', also known as '''copy prevention''' or '''copy restriction''', is any technical measure designed to prevent duplication of information. Copy protection is often emotionally debated, and is thought to sometimes infringe on some users' property rights: for example, the right to make a backup copy of a videotape they have purchased, to install and use computer software on multiple computers, or to upload their music into their digital audio player for easier access and listening.

Note on terminology
The media industries have always referred to the technology as '''copy protection'''. Opponents believe the term encourages people to identify with publishers who benefit from it, rather than the users who are restricted by it. [http://www.gnu.org/philosophy/words-to-avoid.html#Protection] '''Copy prevention''' and '''Copy control''' are neutral terms that are sometimes used instead. The term is also often related and/or confused to the concept of digital rights management. Digital rights management is a more general term because it includes all sort of management of works, including copy restrictions, but copy protection may include measures that are not digital. A more likely description to this is "technical protection measures" (TPM), which is often defined as the use of technological tools in order to restrict the use and/or access to a digital work. Using the scientific classification as an analogy, DRM is the genus, and TPM is the species.

Business rationale
Copy protection is most commonly found on videotapes, DVDs, computer software discs, video game discs and cartridges, and more recently, some audio compact disc CDs. Historically, most companies that publish works on these media have believed that copy protection will increase the company's revenues, by limiting the ability of the consumer to make copies of the media. In the absence of copy protection, most of these media are relatively easy to copy in their entirety using a machine (as opposed to photocopying each page of a book). This results in a situation where consumers can easily make copies of the items to give to their friends, a practice known as "casual copying." Because this practice reduces the number of people in the market who lack the product, it is therefore argued that the ease of copying such media robs the company of potential customers. Some other publishers have avoided copy-protecting their products, on the theory that the resulting inconvenience to their users outweighs any benefit of frustrating "casual copying." No formal studies have been conducted which show a monetary benefit one way or the other. 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.

Technical challenges
From a technical standpoint, it would seem theoretically 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. The basic technical fact is that all types of media require a "player"—a CD player, DVD player, videotape player, computer, or video game console, to give five examples. The player has to be able to read the media in order to display it to a human. In turn, then, logically, a player could be built that first reads the media, and then writes out an exact copy of what was read, to the same type of media, or perhaps to some other format, such as a file on a hard disk. At a minimum, digital copy protection of most media 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 movie 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 loudspeaker speaker output or headphone jacks) and, once redigitized into an unprotected form, duplicated indefinitely. Copying text in this way is more tedious, but the same principle applies: if it can be printed or displayed, it can also be scanned and Optical character recognition OCRed. 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" (for the time being, at least, but see Fritz chip). 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. They can be encrypted in a fashion which is unique for each user's computer, and the decryption system can be made tamper resistance tamper-resistant (''see also'' traitor tracing).

Copy protection on older media
Copy protection has been attempted in many ways, long before computers and digital media entered the picture. For example, the ancient practice of watermarking is an attempt to at least prove the authenticity of the original, though this does not itself prevent copying. The music industry in particular has long sought a reliable copy protection method—early attempts included adding a high frequency ''spoiler signal'' to an analog recording so that tape recorders would generate an unpleasant whistle when the spoiler heterodyned with the bias oscillator. These attempts were largely unsuccessful, since the spoiler was either audible to the listener on the original tape, or else so high that it would not be reproduced reliably when played back.

Copy protection for computer software
Copy protection for early home computer software, especially for games, started a long cat-and-mouse struggle between publishers and software cracking crackers. These were (and are) programmers who as a hobby would defeat copy protection on software, add their pseudonym alias to the title screen, and then distribute the cracked product to the network of warez Bulletin board system BBSes or Internet sites that specialized in distributing unauthorized copies of software. Software copy protection schemes for early computers such as the Apple II family Apple II and Commodore 64 computers depended on precise knowledge of what exactly would happen if the hardware were forced to do something unusual, such as to read a disk sector that was unformatted, or to take just a few microseconds longer than necessary when instructing the floppy disk floppy disk drive arm motor to move. This sort of physical copy protection continues today on software shipped on CD-ROM, with companies like Macrovision and Sony providing copy protection schemes that work by writing data to places on the CD-ROM where a CD-R drive cannot normally write. Such a scheme has been used for the Sony PlayStation and cannot be circumvented easily without the use of a modchip. For software publishers, a less expensive method of copy protection is to write the software so that it requires some evidence from the user that they have actually purchased the software, usually by asking a question that only a user with a software manual could answer (for example, "What is the 4th word on the 6th line of page 37?"). This approach can be defeated by users who have the patience to copy the manual with a photocopier, and it also suffers from BTO vulnerability, so that once crackers circumvent the copy protection on a piece of software, the resulting cracked product is more convenient than the original software, creating a disincentive to buying an original. As a result, user-interactive copy protection of this kind has mostly disappeared. Other software copy protection techniques include: *A dongle, a piece of hardware containing an electronic serial number that must be plugged into the computer to run the software. This adds extra cost for the software publisher, so dongles are uncommon for games and are found mostly in expensive high-end software packages. *A registration key, a series of letters and numbers that is asked for when running the program. Many computer games use registration keys. The software will refuse to run if the registration key is not typed in correctly, and multiplayer games will refuse to run if another user is online who has used the same registration key. *Name & Serial, a name and serial number that is given to the user at the time the software is purchased, and is required to install it. *Keyfile, which requires the user to have a keyfile in the same directory as the program is installed to run it. *A phone activation code, which requires the user to call a number and register the product to receive a computer-specific serial number. *Internet product activation, which requires the user to connect to the Internet and type in a serial number so the software can "call home" and notify the manufacturer who has installed the software and where, and prevent other users from installing the software if they attempt to use the same serial number. *Encrypted code that is used to enforce other protection mechanisms The two latter methods imply tying the software installation to a specific machine by noting some particular unique feature of the machine. Some machines have a serial number in Read-only memory ROM, while others do not, and so some other metric, such as the date and time (to the second) of initialisation of the hard disk can be used. On machines with Ethernet cards, the MAC address, which is unique and factory-assigned, is a popular surrogate for a machine serial number; however, this address is programmable on modern cards. These schemes have all been criticized for causing problems for validly licensed users who upgrade to a new machine, or have to reinstall the software after reinitialising their hard disk. Some Internet product activation products can allow replacement copies to be issued to registered users or multiple copies to the same licensee. Like all software, copy-protection software sometimes contains bugs, whose effect may be to deny access to validly licensed users. As with all similar schemes, they are often easy to crack, and the resulting cracked software is perceived as being BTO vulnerability more valuable than the uncracked version. There is also the tool of Software blacklist software blacklisting that is used to enhance certain copy protection schemes.

Case study: Steam
The best known form of Internet activation is Valve's Steam (content delivery) Steam system. Using Steam, players can either download games directly from Valve or register store bought copies; in either case that copy of the purchased game is inextricably linked to the player's account on Steam and cannot be transferred without either passing on Steam account details or, in the case of store bought games, getting a new CD key. While the system has its advantages and has been extremely successful in reducing illicit copying of Valve's games, it is not without criticisms. When Valve's flagship game ''Half-Life 2'' was released, millions of players attempted to register their copies of the game simultaneously. This lead to an overload of Valve's servers and temporarily denied legitimate customers access to their purchased game.

Copy protection specific to old games
During the 80's and 90's, computer games sold on audio cassette and floppy disks were usually protected with a 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 at installation — these computers lacked hard disks to install to — but every time the game was executed. Sometimes the copy protection code was needed not at launch, but at a later point in the game. This helped the gamer to experience the game (e.g. as a demonstration) and perhaps could convince him to buy it by the time the copy protection point was reached. Several imaginative and creative methods have been employed, in order to be both fun and hard to copy. These include: *The most common method ("''What is the 13th word on the 7th line of page 22?''") was often used at the beginning of each game session, but as it proved to be troublesome and tiring for the players declined in popularity. *Manual containing information and hints vital to the completion of the game, like answers to riddles (''Conquests of Camelot'', ''King's Quest 6''), recipes of spells (''King's Quest 3''), keys to deciphering non-Latin writing systems (''Ultima'' series), maze guides (''Manhunter (game) Manhunter''), dialogue spoken by other characters in the game (''Wasteland'', ''Dragon Wars'') or a radio frequency to use to communicate with a character to further a game ''Metal Gear Solid''. *Some sort of code with symbols, not existing on the keyboard or the ASCII code. This code was arranged in a grid, and had to be entered via a virtual keyboard at the request "''What is the code at line 3 row 2?''". These tables were printed on dark paper (''Maniac Mansion''), or were visible only through a red transparent layer (''Indiana Jones and the Last Crusade''), making the paper very difficult to photocopy. Another variant of this method was a card with color sequences at each grid reference that had to be entered. This also prevented photocopying. *''The Secret of Monkey Island'' offered one of the most imaginative protection keys: a rotating wheel with halves of pirate's faces. The game showed a face composed of two different parts and asked when this pirate was hanged on a certain island. The player then had to match the faces on the wheel, and enter the year number that appeared on the island-respective hole. Its ''Monkey Island 2 sequel'' had the same concept, but with magic potion ingredients. *''Superior Soccer'' had no outward signs of copy protection, but if it decided it was illegally copied, it would make the soccer ball in the game invisible, thus making it impossible to play the game. *''Zork'' games such as ''Beyond Zork'' and ''Zork Zero'' came with "feelies" which contained information vital to the completion of the game. For example, the parchment found from Zork Zero contained clues vital to solving the final puzzle. However, whenever the player attempts to read the parchment, they are referred to the game package. The in-game help function alluded to this form of control with the response "good luck, blackbeard" to queries that were unsolvable without the original game materials. *Some game companies offered "value-added" goodies with the package, like funny manuals, posters, comics, storybooks or fictional documentation concerning the game (e.g. the Grail Diary for Indiana Jones or a police cadet notebook with ''Police Quest'' or the Hero's manual of ''Quest for Glory'') in order to entice gamers to buy the package. *The lenslok system used a plastic prismatic device, shipped with the game, which was used to descramble a code displayed on screen.

Copy protection for videotape
Companies like Macrovision provide schemes to videotape publishers making copies unusable if they were created with a normal VCR. All major videotape manufacturers license Macrovision or similar technologies to copy protect their videotapes. Starting in 1985 with the video release of "The Cotton Club", Macrovision has licensed to publishers a technology that exploits the automatic gain control feature of VCRs by adding pulses to the vertical blanking sync signal. These pulses do not affect the image a consumer sees on his TV, but do confuse the recording-level circuitry of 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 uses a legal strategy of patenting its video AGC system, giving it a more straightforward basis to shut down manufacture of any device that descrambles it than often exists in the DRM world.

Copy protection for audio CDs
By 2000, Napster had become a popular mainstream hobby, and several music publishers responded by starting to sell some CDs with various copy protection schemes. Most of these are playback restrictions that aim to make the CD unusable in computers with CD-ROM drives, leaving only dedicated audio CD players for playback. This does not, however, prevent such a CD from being copied via analogue connections, which has led critics to question the usefulness of such schemes. CD copy protection is achieved by assuming certain feature levels in the drives: The CDDA CD Digital Audio is the oldest CD standard and forms the basic feature set beyond which dedicated audio players need no knowledge. CD-ROM drives additionally need to support mixed mode CDs (combined audio and data tracks) and multi-session CDs (multiple data recordings each superseding and incorporating data of the previous session). The play preventions in use intentionally deviate from the standards and intentionally include malformed multisession data or similar with the purpose of confusing the CD-ROM drives to prevent correct function. Simple dedicated audio CD players would not be affected by the malformed data since these are for features they don't support — for example, an audio player will not even look for a second session containing the copy protection data. In practice, results vary wildly. CD-ROM drives may be able to correct the malformed data and still play them to an extent that depends on the make and version of the drive. On the other hand, some audio players may be built around drives with more than the basic intelligence required for audio playback. Some car radios with CD playback, portable CD players, CD players with additional support for data CDs containing MP3 files, and DVD players have had problems with these CDs. The deviation from the Red Book (audio CD standard) Red Book standard that defines audio CDs required the publishers of these copy-protected CDs to refrain from using the official CDDA logo on the discs or the cases. The logo is a trademark owned by Philips and Sony and licensed to identify compliant audio discs only. To prevent dissatisfied customers from returning CDs which were misrepresented as compliant audio CDs, such CDs also started to carry prominent notices on their covers. In general the audio can always be extracted by applying the principle of the analog hole. Additionally, such programs as ISOBuster may be capable of producing hidden audio files. Examples of CD copy protection schemes are Cactus Data Shield and Copy Control.

Sony CD copy protection controversy
:''Main article: 2005 Sony CD copy protection controversy'' In late 2005, Sony BMG Music Entertainment Sony BMG Music sparked the 2005 Sony CD copy protection controversy Sony CD copy protection controversy when it included a form of copy protection called Extended Copy Protection ("XCP") on discs from at least 20 artists. Upon inserting such a disc in the CD drive of a computer running Microsoft Windows, the ECP software would be installed. If CD ripper software were to subsequently access the music tracks on the CD, ECP would substitute white noise for the audio on the disc. Technically inclined users found that ECP resembled a root kit, in that after installation, ECP went to great lengths to disguise its existence; the code even attempted to disable the computer's CD drive if ECP were forcibly removed. ECP's efforts to cloak itself unfortunately allowed writers of malware to amplify the damage done by their software, hiding the malware under ECP's cloak if ECP had been installed on the victim's machine. Several publishers of antivirus and anti-spyware software updated their products to detect and remove ECP if found, on the grounds that it is a trojan horse (computing) trojan horse or other malware; and an assistant secretary for the United States' Department of Homeland Security chastised companies that would cause security holes on customers' computers. Facing apparently unanimous resentment, Sony BMG issued a product recall for all discs including ECP, and announced it was suspending use of ECP on future discs.

Copy protection in recent digital media
Image:CopyProtectionAwareness.gif Motion Picture Association of America right|107px|thumb|The [[Motion Picture Association of America|MPAA's "Copy Protection Awareness Icon" for DVDs..html" title="Meaning of MPAA.html" title="Meaning of right|107px|thumb|The [[Motion Picture Association of America|MPAA">right|107px|thumb|The [[Motion Picture Association of America|MPAA's "Copy Protection Awareness Icon" for DVDs.">MPAA.html" title="Meaning of right|107px|thumb|The [[Motion Picture Association of America|MPAA">right|107px|thumb|The [[Motion Picture Association of America|MPAA's "Copy Protection Awareness Icon" for DVDs. More recently, publishers of music and movies in digital form have turned to encryption to make copying more difficult. Content-scrambling system CSS, which is used on DVDs, is a famous example of this. It is a form of copy protection that uses 40-bit encryption. Copies will not be playable since they will be missing the key, which is not writable on DVD-R or DVD-RW discs. With this technique, the work is encrypted using a key only included in the firmware of "authorized" players, which allow only "legitimate" uses of the work (usually restricted forms of playback, but no conversion or modification). The controversial Digital Millennium Copyright Act provides a legal protection for this in the US, that would make it illegal to distribute "unauthorized" players—which was supposed to eliminate the possibility of building a DVD copier. However, CSS and other such software-based solutions have been reverse engineering reverse engineered (see DeCSS), providing access to the encryption keys and methods. The cat-and-mouse struggle continues. In the future, software cracking may become more difficult to perform with the release of the Fritz-chip in combination with certain Microsoft software like Nexus in the next major operating system from Microsoft, Windows Vista.

See also
*2005 Sony CD copy protection controversy *Broadcast flag *DAEMON Tools *Digital rights management *Extended Copy Protection *Rob Northen copylock *SafeDisc *StarForce *SecuROM *Trusted Computing *PELock

External links

- Evaluating New Copy-Prevention Techniques for Audio CDs
- Loss of confidential proprietary information cost the average business $42,600 in 2004
- The real deal of copy protections
- Devaluing the Product - Sony CDs Threaten PCs - 11/02/05 article on how copy protection on Sony music CDs can damage home systems.
- Code Morphing
- EXECryptor software copy protection
- X-Formation - Provider of software copy protection solutions Category:Authentication methods Category:Digital rights management de:Kopierschutz es:ProtecciÃ³n de copia ja:ã‚³ãƒ”ãƒ¼ã‚¬ãƒ¼ãƒ‰ ru:Ð—Ð°Ñ‰Ð¸Ñ‚Ð° Ð¾Ñ‚ ÐºÐ¾Ð¿Ð¸Ñ€Ð¾Ð²Ð°Ð½Ð¸Ñ? see Copy protection

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