Copy protection

Copy protection, also known as content protection, copy obstruction, copy prevention and copy restriction, refer to techniques used for preventing the reproduction of software, films, music, and other media, usually for copyright reasons.^[1]

Terminology

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)^{[citation needed]}, which is often defined as the use of technological tools in order to restrict the use or access to a work.

Business rationale

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

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 copy 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 copying.

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 he/she has 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 evolve beyond 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.

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. 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. If to another disk, then the result is an exact duplicate of the copy protected disc.

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.

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 crackers. These were (and are) programmers who would defeat 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.

Software copy protection schemes for early computers such as the Apple II and Commodore 64 computers were extremely varied and creative because most of the floppy disk reading and writing was controlled by software, not by hardware; for the IBM-PC these were known as 'booters'. The first copy protection was for cassette tapes and consisted of a loader at the beginning of the tape, which read a specially formatted section which followed.

The first protection of floppy disks consisted of changing the address marks, bit slip marks, data marks, or end of data marks for each sector. For example, Apple’s standard sector markings were:

• D5 AA 96 for the address mark. That was followed by track, sector, and checksum.
• DE AA EB concluded the address header with what are known as bit slip marks.
• D5 AA AD was used for the data mark and the end of data mark was another DE AA EB.

Changing any of these marks required changing the software which read the floppy disk, but produced a disk that could not be copied. Some systems used complicated systems that changed the marks by track or even within a track.

By 1980, the first nibble copier, Locksmith, was introduced. These copiers reproduced copy protected floppy disks an entire track at a time, ignoring how the sectors were marked. This was harder to do than it sounds, because Apple disks did not use the index hole to mark the start of a track. Tracks could start anywhere. Nevertheless, Locksmith copied Apple II disks by taking advantage of the sync fields between sectors, which consisted of a long string of FF (hex) bytes between each sector. It found the longest string of FFs, which occurred between the last and first sectors on each track, and began writing the track in the middle of that.

Ironically, Locksmith would not copy itself. The first Locksmith measured the distance between sector 1 of each track. Copy protection engineers quickly figured out what Locksmith was doing and began to use the same technique to defeat it. Locksmith countered by introducing the ability to reproduce track alignment and prevented itself from being copied by embedding a special sequence of nibbles, that if found, would stop the copy process. Henry Roberts (CTO of Nalpeiron), a graduate student in computer science at the University of South Carolina, reverse engineered Locksmith, found the sequence and distributed the information to some of the 7 or 8 people producing copy protection at the time.

For some time, Locksmith continued to defeat virtually all of the copy protection systems in existence. The next advance came from Henry Roberts' thesis on software copy protection, which devised a way of replacing Apple’s sync field of FFs with random appearing patterns of bytes. Because the graduate student had frequent copy protection discussions with Apple’s copy protection engineer, Apple developed a copy protection system which made use of this technique.

Henry Roberts then wrote a competitive program to Locksmith, Back It UP. He devised several methods for defeating that, and ultimately a method was devised for reading self sync fields directly, regardless of what nibbles they contained.

The back and forth struggle between copy protection engineers and nibble copiers continued until the Apple II became obsolete and was replaced by the IBM PC and its clones.

Floppy disks were replaced by CDs as the preferred method of distribution, 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 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 the fact 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 the 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. Rainbow (SafeNet), HASP (Aladdin Knowledge Systems), iLok (Copy Protection) and Matrix Software License Protection System UniKey ^[3] are popular dongle protection schemes utilizing a USB dongle. For the production of even more restrictive software, a dongle product that supports code porting mechanism is one choice available to software developers.
• Bus encryption and encrypted code for use in secure cryptoprocessors. This prevents copying and tampering of programs used in high security environments such as ATMs. This hardware solution is based on the fact that unlike music, video, and text that must eventually be revealed to users to be heard, viewed, or read, program instructions are needed only by the cryptoprocessor that decrypts and executes them.
• A product 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, or exchange encrypted files with the vendor, 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. Microsoft's Windows Genuine Advantage system is a far-reaching example of this.
• Device ID verification, specifically tying a copy of software to a computer or mobile device based on a unique identifier only known to that device (like the IMEA code of a smartphone), a process utilized by Appuware, Inc. for its app piracy prevention scheme.
• Protection by code morphing or code obfuscation. The code morphing is multilevel technology containing hundreds of unique code transformation patterns. In addition this technology includes the special layer that transforms some commands into virtual machine commands (like P-Code). Code obfuscation turns binary code into an undecipherable mess that is not similar to normal compiled code, and completely hides execution logic of the protected code.

Copy protection methods usually tie the installed software to a specific machine by involving some unique feature of the machine. Some machines have a serial number in ROM, while others do not, and so some other metric, such as the date and time (to the second) of initialization of the hard disk can be used. On machines with Ethernet cards, the MAC address, which is factory-assigned and intended to be unique, is a popular surrogate for a machine serial number; however, this address is programmable on modern cards. With the rise of virtualization the practice of locking has to add to these simple hardware parameters to still prevent copying.^[4]

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 reinitializing their hard disk. Some Internet product activation products allow replacement copies to be issued to registered users or multiple copies to the same license.

Like all software, copy-protection software sometimes contains bugs, whose effect may be to deny access to validly licensed users. Most copy protection schemes are easy to crack, and the resulting cracked software is then more valuable than the non-cracked version, because users can make additional copies.

In his 1976 Open Letter to Hobbyists, Bill Gates complained that "most of you steal your software." However, Gates initially rejected copy protection and said "It just gets in the way."

There is also the tool of software blacklisting that is used to enhance certain copy protection schemes.

Copy protection specific to XX century games

During the 1980s and 1990s, computer games sold on audio cassette and floppy disks were sometimes 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 but every time the game was executed.^[5]

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, it declined in popularity (for example, X-COM: UFO Defense used it too, but was later removed by the official v1.4 patch). A variant of this technique involved matching a picture provided by the game to one in the manual and providing an answer pertaining to the picture (Ski or Die and 4D Boxing used this technique). Buzz Aldrin's Race Into Space (in the floppy version but not the CD version) incorporated a copy protection scheme that required the user to input an astronaut's total duration in space (available in the manual) before the launch of certain missions. If the answer was incorrect, the mission would suffer a catastrophic failure.
• Manuals 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, see also Ultima writing systems), maze guides (Manhunter), dialogue spoken by other characters in the game (Wasteland, Dragon Wars), excerpts of the storyline (most Advanced Dungeons and Dragons games and Wing Commander I), 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, Uplink), 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—most famously used on the ZX Spectrum version of Jet Set Willy—was a card with color sequences at each grid reference that had to be entered before starting the game. 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 sequel had the same concept, but with magic potion ingredients. Other games that employed the code wheel system include games from Accolade like Star Control.
• 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.
• The Lenslok system used a plastic prismatic device, shipped with the game, which was used to descramble a code displayed on screen.

While not strictly a software protection, 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 or a copy of the National Inquisitor newspaper in Zak McKracken) in order to entice gamers to buy the package. This trend is re-emerging in modern gaming as an incentive to both buy games and discourage their resale; some games like Forza Motorsport 3 and Dragon Age: Origins provide bonus in-game material that will only be given if one buys the game new.

Copy protection methods of recent video game console systems

When Sega's Dreamcast was released in 1998, it came with a newer disc format, called the GD-ROM. Using a modified CD player, one could access the game functionality. Using a special swap method could allow reading a GD-ROM game through a CD-ROM just using common MIL-CD (standard CD Boot loading, commonly found on Windows Installation Discs, Linux Live CDs, and others). Dreamcasts sold after October 2000 contain a newer firmware update, not allowing MIL-CD boot.

The Xbox has a specific function: Non-booting or non-reading from CDs and DVD-Rs as a method of game copy protection. Also, the Xbox is said to use a different DVD file system (instead of UDF). It has been theorized that the discs have a second partition that is read from the outside in (opposite current standards thus making the second partition unreadable in PC DVD drives) which give the tracks the appearance that the disc was spun backwards during manufacture. The Xbox 360 copy protection functions by requesting the DVD drive compute the angular distance between specific data sectors on the disc. A duplicated DVD will return different values than a pressed original would.

The PlayStation 2 has a map file that contains all of the exact positions and file size info of the CD in it, which is stored at a position that is beyond the file limit. The game directly calls the position at where the map file is supposed to be. This means that if the file is moved inside the limit, it is useless since the game is looking outside the limit for it, and the file will not work outside of the limit, making any copied disc unusable without a mod chip or the use of FMCB (free memory card boot). FMCB uses the memory card to trick the built-in DVD video software into booting copied games. Before a copied game can be played, it must have been patched with a free application.

Nintendo's Wii and Nintendo GameCube have their own specialty format for copy protection. It is based on DVD/miniDVD (Game Cube) technology; each disc contains some deliberately placed defects. The exact positions of these defects, which differ for each produced disc, is encoded encrypted in the BCA of each disc. The BCA is readable on most standard DVD-ROM Drives, but consumer burners can reproduce neither the BCA nor the defects. As an additional obfuscation mechanism, the on-disc sector format is a little bit different from normal DVDs. Nevertheless, it can be read using some consumer DVD-ROM drives with a firmware modification or "debug mode".

The PSP, except the PSP Go, uses the Universal Media Disc, a media format similar to a MiniDisc. It holds about 1.2 GB. Although it cannot be copied, one can make an ISO image (a file version of the UMD) on a memory card and play it on custom firmware, which can be installed on the PSP.

The PlayStation 3 uses Blu-ray BD-ROM discs. In addition to any protection provided by the console itself, the BD-ROM format's specification allows for a ROM-Mark which cannot be duplicated by consumer-level recorders. The BD-ROM format, in addition, has a notably large file size in the neighborhood of 40-50 gigabytes per game, making it unwieldy for online file-sharing, a major method of video game copying.

Proposed general purpose copy protection methods

There is another protection method that is not out yet, US Patent Office for Application Number 11678137. Each and every copy of a protected program gets its own internal intelligence, interpretable only by itself, which includes time of program creation, etc., etc..^{[clarification needed]} Each copy of the game or program must be compiled or otherwise created at the time of purchase. Also, the maker must keep track of a subset of each and every instance of the newly created specialty software in case the user emails in for new keys, say for a reinstall. Perhaps even the purchasers name would be encoded and included as part of the intelligence. The number of permissible occurrences of requests for new key codes, say, 5 times, can be controlled by the program maker. If someone cracks the code for that particular copy of the program, still, it will work only for that copy, and only in the time frame that the internal intelligence says it can be installed.

Copy protection for videotape

Companies such as Macrovision and Dwight Cavendish provided schemes to videotape publishers making copies unusable if they were created with a normal VCR. All major videotape duplicators licensed Macrovision or similar technologies to copy protect video cassettes for their clients or themselves.

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.^[6] 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 has patented methods of defeating copy prevention,^[7] 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 or by ripping the CD under operating systems such as Linux (which is effective since copy-protection software is generally written for Microsoft Windows), 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 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 do not 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 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, Copy Control, and Data Position Measurement.

Copy protection in recent digital media

More recently, publishers of music and films in digital form have turned to encryption to make copying more difficult. 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, encryption schemes designed for mass-market standardized media such as DVD suffer from the fundamental weaknesses that consumers have physical access to the devices containing the keys, and once implemented, the copy-protection scheme can never be changed without breaking the forward compatibility of older devices (or the backward compatibility of newer media). Since consumers are highly unlikely to buy new hardware for the sole purpose of preserving copy protection, manufacturers have been prevented from enhancing their DRM technology until recently, with the release of next-generation media such as HD DVD and Blu-ray Disc. This period represents more than enough time for the encryption scheme to be defeated by determined attackers. For example, the CSS encryption system used on DVD Video was broken within three years of its market release in November 1996 (see DeCSS), but has not been changed since, because doing so would immediately render all DVD players sold prior to the change incapable of reading new DVDs—this would not only provoke a backlash amongst consumers, but also restrict the market that the new DVDs could be sold to. More recent DVDs have attempted to augment CSS with additional protection schemes. Most modern schemes like ARccOS Protection use tricks of the DVD format in an attempt to defeat copying programs, though it is noted that any scheme must stay within the bounds of the DVD Video format, limiting the possible avenues of protection—and making it easier for hackers to learn the innards of the scheme and find ways around it.

The newest generations of optical disc media, HD DVD and Blu-ray Disc, attempt to address this issue. Both formats employ the Advanced Access Content System, which provides for several hundred different decryption keys (for the varying models of players to hit the market), each of which can be invalidated ("revoked") should one of the keys be compromised. Revoked keys simply will not appear on future discs, rendering the compromised players useless for future titles unless they are updated to fix the issue. For this reason, all HD-DVD players and some Blu-ray players include an ethernet port, to give them the ability to download DRM updates. Blu-ray Disc goes one step further with a separate technique called BD+, a virtual machine that can execute code included on discs to verify, authorize, revoke, and update players as the need arises. Since the protection program is on the disc rather than the player, this allows for updating protection programs within BD's working life by simply having newer programs included on newer discs.

Notable copy protection payloads

Over time, software publishers (especially in the case of videogames) became creative about crippling the software in case it was illegally copied. These games would initially show that the copy was successful, but eventually render themselves unplayable via subtle methods.

• 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, making it impossible to play the game.
• While the copy protection in Zak McKracken and the Alien Mindbenders was not hidden as such, the repercussions of missing the codes was unusual: the player would end up in jail (permanently), and the police officer would give a lengthy and condescending speech about software copying.
• In case of copied versions of Settlers 3, the iron smelters - who are essential to create weapons - would only produce pig irons, making the players inevitably lose weapons because of the lack of armour.^[8]
• Bohemia Interactive Studio developed a unique and very subtle protection system for its game Operation Flashpoint: Cold War Crisis. Dubbed FADE, if it detects an unauthorized copy, it does not inform the player immediately but instead progressively corrupts aspects of the game (such as reducing the weapon accuracy to 0) to the point that it eventually becomes unplayable. The message "Original discs don't FADE" will eventually appear if the game is detected as being an unauthorized copy. FADE is also used in ArmA II.^[9] They continued these methods in Take On Helicopters, where the screen would blur and distort when playing a pirated copy.^[10]
• More recently, Batman: Arkham Asylum implemented a copy protection system where the game disables Batman's glide system and various other features, rendering the players to be unable to continue beyond a certain point.^[11]
• 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. Exile is known to have used this technique but it is a common technique in general usage.
• The PC version of Grand Theft Auto IV has a copy protection that swings the camera as though the player was drunk. If the player entered a vehicle it will automatically throttle, making it difficult to steer. It also damages the vehicle, making it vulnerable to collisions and bullets.
• In Earthbound, unauthorized copies of the game will trigger a checksum that makes random encounters appear much more often than in an authorized copy, and if the player progresses through the game without giving up (or cracks this protection), a second checksum code will activate before the final boss battle, freezing the game and deleting all the save files.^[12]
• In an unauthorized version of the PC edition of Mass Effect, the game save mechanism would not work and the in-game galactic map would cause the game to crash. As the galactic map is needed to travel to different sections of the game, the player would be stuck in the first section of the game.
• If an unauthorized version of The Sims 2 was used, the Build Mode would not work properly. Walls would not be able to be built on the player's property, which prevents the player from building any custom houses. Some furniture and clothing selections would not be available too.
• A March 2009 update to the BeeJive IM iPhone app included special functionality for users of the pirated version: the screen would read "PC LOAD LETTER" whenever the user tried to establish a connection to any IM service, then quickly switch to a YouTube clip from the movie Office Space.^[13]
• Red Alert 2 has a copy protection, where if an illegal version of it is detected, the player's entire base would be destroyed within 30 seconds of the player joining a match.
• The DS version of Michael Jackson: The Experience has a copy protection system where vuvuzela noises are heard as the music is playing, no visible notes, making the game impossible to play, & the game freezing upon the player pausing it.
• Older versions of Autodesk 3ds Max use a dongle for copy protection; if it is missing, the program will randomly corrupt the points of the user's model during usage, destroying their work.
• Older versions of CDRWIN used a serial number for initial copy protection. However, if this check was bypassed, a second hidden check would activate causing a random factor to be introduced into the CD burning process, producing corrupted "coaster" disks.
• Terminate, a BBS terminal package, would appear to operate normally if cracked but would insert a warning that a pirated copy was in use into the IEMSI login packet it transmitted, where the sysop of any BBS the user called could clearly read it.
• Ubik's Musik, a music creation tool for the Commodore 64, would transform into a Space Invaders game if it detected that a cartridge-based copying device had attempted to interrupt it. This combined copy protection and an easter egg, as the message that appears when it occurs is not hostile ("Plug joystick in port 1, press fire, and no more resetting/experting!")
• The Amiga version of Bomberman featured a multitap peripheral that also acted as a dongle. Data from the multitap was used to calculate the time limit of each level. If the multitap was missing, the time limit would be calculated as 0, causing the level to end immediately.
• Never Mind, a puzzle game for the Amiga, contained code that caused any pirated version of the game to behave as a demo. The game would play three levels sampled from throughout the game, and then give the message "You have completed three levels; however there are 100 levels to complete on the original disc."
• While not a destructive payload. In Spyro: Year of the Dragon A Character named Zoe will tell the player outside the room containing the balloon to Midday Garden Home and several other areas that they are using a pirated copy. However this has no impact on the gameplay itself and just proves to be a minor annoyance.
• The Atari Jaguar console would freeze at startup and play the sound of an enraged jaguar snarling if the inserted cartridge failed the initial security check.
• The Lenslok copy protection system gave an obvious message if the lens-coded letters were entered incorrectly, but if the user soft-reset the machine, the areas of memory occupied by the game would be flooded with the message "THANK YOU FOR YOUR INTEREST IN OUR PRODUCT. NICE TRY. LOVE BJ/NJ" to prevent the user examining leftover code to crack the protection.
• An update to the sandbox game Garry's Mod enabled a copy protection mechanism that outputs the error "Unable to shade polygon normals" if the game detects that it is pirated. The error also includes the user's Steam ID as an error ID, meaning that pirates can be identified by their Steam account when asking for help about the error on the Internet.
• The Atari version of Alternate Reality: The Dungeon would have the player's character attacked by two unbeatable "FBI Agents" if it detected a pirated version. The FBI agents would also appear when restoring a save which was created by a pirated version, even if the version restoring the save was legal.
• VGA Planets, a play-by-BBS strategy game, contained code in its server which would check all clients' submitted turns for pirated registration codes. Any player deemed to be using an illegal copy, or cheating in the game, would have random forces destroyed throughout the game by an unbeatable enemy called "The Tim Continuum" (after the game's author, Tim Wissemann). A similar commercial game, Stars!, would issue empty turn updates for players with invalid registration codes, meaning that none of their orders would ever be carried out.
• On a copied version of the original PC version of Postal, as soon as the game was started the player character would immediately shoot himself in the head.

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 pirated 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.

See also

• Alcohol 120%
• Aladdin Knowledge Systems
• BD+
• Broadcast flag
• Bus encryption
• CD-Cops
• CI+
• Daemon Tools
• Code morphing
• Code obfuscation
• Digital rights management
• Digital watermarking
• Encryption software
• Extended Copy Protection
• Floating licensing
• Game Jackal
• Game-altering device
• iLok (Copy Protection)
• Libcrypt
• License manager
• List of license managers
• Product activation
• Protect Software
• Rob Northen copylock
• SafeDisc
• SafeNet
• Secure cryptoprocessor
• SecuROM
• Software anti-tamper
• Sony BMG CD copy protection scandal
• StarForce
• TAGES
• Tamper resistance
• Trusted Computing
• Vendor lock-in
• Watermark detection

Notes and references

1. ^ Thomas Obnigene, DVD Glossary, filmfodder.com 2007. Retrieved July 19, 2007.
2. ^ Confusing Words and Phrases that are Worth Avoiding, GNU Project - Free Software Foundation (FSF).
3. ^ UniKey is a driverless dongles based on HID technologies, which are manufactured by SecuTech Solution Inc..
4. ^ Dominic Haigh (2010-06-28). "Copy protection on virtual systems". Knol.google.com. http://knol.google.com/k/dominic-haigh/securing-software-licenses-in-virtual/2zijsseqiutxo/5#. Retrieved 2010-12-06. 
5. ^ Retro Gamer issue 83, "Don't copy that floppy"
6. ^ 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.
7. ^ One such patent is U.S. Patent 5,625,691.
8. ^ Sven Liebich, Germany. "Settlers3.com". Settlers3.com. http://www.settlers3.com/forum/bulletin.htm. Retrieved 2010-12-06. 
9. ^ "FADE Game Copy Protections". GameBurnWorld. http://www.gameburnworld.com/protections_fade.shtml. Retrieved 2010-12-06. 
10. ^ http://www.gamepolitics.com/2011/11/10/bohemia-interactive-details-unique-anti-piracy-methods
11. ^ "Afterdawn.com". Afterdawn.com. 2009-09-09. http://www.afterdawn.com/news/archive/19289.cfm. Retrieved 2010-12-06. 
12. ^ "MOTHER 2 / EarthBound Anti-Piracy Measures". Starmen.Net. http://starmen.net/mother2/gameinfo/antipiracy/. Retrieved 2010-12-06. 
13. ^ Post Store (2009-03-19). "Beejive IM Moves To Block Out iPhone Pirates". washingtonpost.com. http://www.washingtonpost.com/wp-dyn/content/article/2009/03/19/AR2009031900312.html. Retrieved 2010-12-06. 

External links

• Copy Protection in depth
• Evaluating New Copy-Prevention Techniques for Audio CDs
• CDFreaks Forum - Forum on how to copy all copy protections and digital storage community.
• C64 Preservation Project Discusses and analyzes protections used on old floppy-based systems.
• Comprehensive article on video game piracy and its prevention.