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 like Target card, Best Buy card and Ebay card. Online activation is required to prevent multiple people using the same key. Not all software has a product key, as some publishers may choose to use a different method to protect their copyright, or in some cases, such as free or open source software, copyright protection is not used. Computer games use product keys to verify that the game has not been copied without authorization. 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.
Controversy
Some of the most effective CD key protection is very controversial, due to inconvenience, strict enforcement, harsh penalties and, in some cases, false positives. CD key protection has been linked to Digital Rights Management, in that it uses uncompromising digital procedures to enforce the license agreement.
Inconvenience
Product keys are somewhat inconvenient for end users. Not only do they need to be entered whenever a program is installed, but the user must also be sure not to lose them. Loss of a product key usually means the software is useless once uninstalled, unless, prior to uninstallation, a key recovery application is used. Product keys also present new ways for distribution to go wrong. If a product is shipped with missing or invalid keys, then the CD itself is useless. For example, all copies of originally shipped to Australia without CD keys.
Enforcement and penalties
There are many cases of permanent bans enforced by companies detecting usage violations. It is common for an online system to immediately blacklist a CD key caught running cracks or, in some cases, cheats. This results in a permanent ban. Players who wish to continue use of the software must repurchase it. This has inevitably led to criticism over the motivations of enforcing permanent bans. Particularly controversial is the situation which arises when multiple products' keys are bound together. If products have dependencies on other products, it is common for companies to ban all bound products. For example, if a fake CD key is used with an expansion pack, the server may ban legitimate CD keys from the original game. Similarly, with Valve's Steam service, all products the user has purchased are bound into the one account. If this account is banned, the user will lose access to every product associated with the same account This "multi-ban" is highly controversial, since it bans users from products which they have legitimately purchased and used.
False positives
Bans are enforced by servers immediately upon detection of cracks or cheats, usually without human intervention. Sometimes, legitimate users are wrongly deemed in violation of the license, and banned. In large cases of false positives, they are sometimes corrected However, individual cases may not be given any attention. A common cause of false positives is users of unsupported platforms. For example, users of Linux can run Windows applications through compatibility layers such as Wine and Cedega. This software combination sometimes triggers the game's server anti-cheating software, resulting in a ban due to Wine or Cedega being a Windows APIcompatibility layer for Linux, so it is considered third-party software by the game's server.
