A product key, also known as a Software key, is a specific software-based key for a computer program. It certifies that the copy of the program is original. Activation is sometimes done offline by entering the key, or with software like Windows XP online activation is required to prevent multiple people using the same key.
Computer games use product keys to verify that the game has not been illegally copied; for example, one could not play Battle.net powered games such as Diablo II or StarCraft online without an original/unique product key. Likewise, one is not allowed to play online with two identical product keys at the same time.
Product keys consist of a series of numbers and/or letters. This sequence is typically entered by the user during the installation of computer software, and is then passed to a verification function in the program. This function manipulates the key sequence according to a mathematical algorithm and attempts to match the results to a set of valid solutions.
Standard key generation, where product keys are generated mathematically, is not completely effective in stopping copyright infringement of software as these keys can be distributed. The overall effectiveness of product keys in enforcing software copyrights requires further study. In addition with improved communication from the rise of the Internet more sophisticated attacks on Keys such as cracks (removing the need for a key) and CD key generators have become common.
Because of this, software publishers are increasingly turning to alternative methods of verifying that keys are both valid and uncompromised. One method, product validation, assigns a product key based on a unique feature of the purchaser's computer hardware (such as its MAC address), which cannot be as easily duplicated since it depends on the user's hardware. Other newer methods may involve requiring periodical validation of the CD key with an internet server (for games with an online component, such as Battle.net, this is done whenever the user signs in). The validation can then be performed on the server side, preventing cracks tampering with it (as they do on the client side). The server can also keep a blacklist of all CD keys known to be invalid or which have explicitly been banned, and deny them access.
Recovery of Keys
A key recovery program is a program that is designed to read and decrypt and/or de-obfuscate the key to its original state. When the key is returned to its original state, it may be used to reinstall its corresponding software.
