Copy protection


Copy protection, also known as content protection, copy prevention and copy restriction, is any effort designed to prevent the reproduction of software, films, music, and other media, usually for copyright reasons. Various methods have been devised to prevent reproduction so that companies will gain benefit from each person who obtains an authorized copy of their product. Unauthorized copying and distribution accounted for $2.4 billion in lost revenue in the United States alone in the 1990s, 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. Some methods of copy protection have also led to criticisms because it caused inconvenience for honest consumers, or it secretly installed additional or unwanted software to detect copying activities on the consumer's computer. Making copy protection effective while protecting consumer rights is still an ongoing problem with media publication.

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. 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", 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, 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, grid computing and electronic licensing. 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.

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 ; if a film can be viewed by the human eye, it can also be recorded. In practice, almost-perfect copies can typically be made by tapping into the analog output of a player 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 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.

Methods

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 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

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. To make digital copying more difficult, many programs used non-standard loading methods.
Unauthorized software copying began to be a problem when floppy disks became the common storage media. 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". Apple 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. 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:
Changing any of these marks required fairly minimal changes to the software routines in Apple DOS which read and wrote the floppy disk, but produced a disk that could not be copied by any of the standard copiers, such as Apple's COPYA program. Some protection schemes used more complicated systems that changed the marks by track or even within a track.

1980s Locksmith

Pournelle disliked copy protection 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". 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 without creating products that are unusable."
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 for two reasons: firstly, Apple disks did not use the index hole to mark the start of a track; their drives could not even detect the index hole. Tracks could thus start anywhere, but the copied track had to have this "write splice", which always caused some bits to be lost or duplicated due to speed variations, roughly in the same place as the original, or it would not work. Secondly, Apple used special "self-sync" bytes to achieve agreement between drive controller and computer about where any byte ended and the next one started on the disk. These bytes were written as normal data bytes followed by a slightly longer than normal pause, which was notoriously unreliable to detect on read-back; still, you had to get the self-sync bytes roughly right as without them being present in the right places, the copy would not work, and with them present in too many places, the track would not fit on the destination disk. Locksmith copied Apple II disks by taking advantage of the fact that these sync fields between sectors almost always consisted of a long string of FF bytes. It found the longest string of FFs, which usually occurred between the last and first sectors on each track, and began writing the track in the middle of that; also it assumed that any long string of FF bytes was a sync sequence and introduced the necessary short pauses after writing each of them to the copy. 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, 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.
Copy protection sometimes caused software to not run on clones, such as the Apple II-compatible Laser 128. 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.
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. 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!".

1990s CD-R

Floppy disks were later displaced by CDs as the preferred method of distribution, with companies like Macrovision and Sony providing copy protection schemes that worked by writing data to places on the CD-ROM where a CD-R drive cannot normally write. Such a scheme had been used for the PlayStation and could not 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. However, this approach can be exploited with the patience to copy the manual with a photocopier, and it also suffers from the issue of making the product more inconvenient for the end user to use.

Recent practices

It has become very common for software to require activation by entering some proof of legal purchase such as:
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 of initialization of the hard disk or MAC address of Ethernet cards. With the rise of virtualization, however, the practice of locking has to add to these simple hardware parameters to still prevent copying.
Another approach to associating user and/or machine with serial number is product activation over the Internet, where users are required to have access to the Internet so the information on which serial number is installed on which machine gets sent to a server to be authenticated. Unauthorized users are not allowed to install or use the software. Microsoft's Windows Genuine Advantage system is a far-reaching example of this.
With rise of Cloud computing, requiring Internet access is becoming more popular for software verification. Beyond online authentication, a standalone software may be integrated with the cloud so that key data or code is stored online. This could greatly strengthen the protection; for example, the software could store a property file or execute a process needed by the application in the cloud instead on the user's computer.

Problems and criticisms

The copy protection schemes described above 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 once crackers circumvent the copy protection, the resulting cracked software is then more convenient and hence more valuable than the non-cracked version, because users can make additional copies of the software. Due to this problem, user-interactive copy protection by asking questions from manuals has mostly disappeared.
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.

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.
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 and perhaps could convince them 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:
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.
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 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 provide bonus in-game material that will only be given if one buys the game new.

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. 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. It has been theorized that the discs have a second partition that is read from the outside in 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 returns different values than does a pressed original.
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. 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 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". It is also possible to hack the Wii to install unlicensed software, some of which can use the Wii's own drive to create disc images and then play these copies.
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 on a memory card and play it on custom firmware, which can be installed on the PSP.
The PlayStation 3, Xbox One, and PlayStation 4 use Blu-ray BD-ROM discs. In addition to any protection provided by the consoles themselves, the BD-ROM format's specification allows for a ROM-Mark which cannot be duplicated by consumer-level recorders. While the BD-ROM format does provide considerable capacity, increased consumer bandwidth availability combined with the increased size of games distributed through online channels is rendering this point moot. To prevent the consoles themselves being hacked and used as a means to defeat these protections, contemporary consoles employ trusted hardware paths that authenticate the internal hardware and software prior to operation.
Some game developers, such as Markus Persson, have encouraged consumers and other developers to embrace the reality of unlicensed copying and utilize it positively to generate increased sales and marketing interest.

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 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 their 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, giving it a more straightforward basis to shut down manufacture of any device that descrambles it than often exists in the DRM world.
Another form of copy protection, MicroVision, was designed to prevent VCRs from recording a television program. Cable movie channels rejected it; Michael J. Fuchs of HBO said in 1985 that MicroVision 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".

Audio CDs

Consumer CD recorders included the Serial Copy Management System, which allowed copies to be made from an original, but did not allow a copy of a copy. Professional equipment, including all computer drives, ignores SCMS. Since computer drives ignored SCMS, copies could be made freely, which led to record labels introducing additional copy protection measures.
By 2000, Napster had seen mainstream adoption, and several music publishers responded by starting to sell some CDs with various copy protection schemes. Most of these were playback restrictions that aimed to make the CD unusable in computers with CD-ROM drives, leaving only dedicated audio CD players for playback. This did not, however, prevent such a CD from being copied via an analogue connection or by ripping the CD under operating systems such as Linux, which was effective since copy-protection software was generally written for Microsoft Windows. These weaknesses led critics to question the usefulness of such protection.
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 instructions. CD-ROM drives additionally need to support mixed mode CDs and multi-session CDs.
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 features 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.

Other 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 regular 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. 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. 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, 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, 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, each of which can be invalidated 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.
4K resolution Blu-ray discs augment the existing Blu-ray protections. First, players must be dedicated devices that use protected hardware paths to ensure the entire process chain is not compromised. Second, some media require the use of players able to access the Internet for additional verification.

Notable payloads

Over time, software publishers 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.

Anti-piracy

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, law enforcement agencies, and various international governments 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 imply that it is ethically equivalent to attacking ships on the high seas, kidnapping and murdering the people on them".
Certain forms of Anti-Piracy, 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.

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. In an effort to cut down on this, both large and small film and music corporations have issued DMCA takedown notices, filed lawsuits, and pressed criminal prosecution of those who host these file sharing services.

Other examples