Copy protection - Copy protection for computer software - Encyclopedia II

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 as a hobby would defeat copy protection on software, 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 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 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 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 more valuable than the uncracked version.

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

The most (in)famous form of Internet activation is Valve's 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 upsides (for instance, updates get delivered to the user through the Steam UI) and it has been extremely successful in stemming copying of Valve's games, it also has its criticisms. When Valve's flagship game Half-Life 2 was released, millions of players attempted to register their copies of the game, leading (inevitably) to Valve's servers being unable to take the strain and denying legitimate customers the game they had paid for.

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, like 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 once 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), maze guides (Manhunter), or dialogue spoken by other characters in the game (Wasteland, Dragon Wars).
• 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 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.

Adapted from the Wikipedia article "Copy protection for computer software", under the G.N U Free Docmentation License. Please also see http://en.wikipedia.org/wiki/Main_Page