License key
A license key (also: key code , product key , CD key or product key ) is a letter or number code that must be entered when installing or starting computer software in order to activate it.
Structure and use
A license key usually consists of a sequence of letters and numbers that is divided into several blocks. Using a license key allows program files to be copied, but the software can not be used without the key . This is to prevent the illegal use of unlicensed software . The license key was initially included as a CD key on a physical data carrier ( CD-ROMs / DVD ). A license key is now also used for software that is sold without a data carrier.
The license key (even if it is mistakenly often used synonymously) is to be distinguished from the serial number ; it is rather encoded in it and is generated during installation. While the serial number can be displayed in the installed product, the license key can only be read on the product packaging, product insert or a confirmation email and cannot be derived from the serial number.
history
The license key initially came with software CD-ROMs . The first programs secured in this way were the Windows 95 operating system and the Microsoft Office package.
By default, the license key must be entered during installation. Since the mid-2000s, it has been possible for many programs to install them without a valid license key and to run them in a test or demo mode , which only has a limited runtime and possibly limited functionality. The full version can then be activated by entering a license key , especially with shareware programs.
safety
License keys can be checked for authenticity by the software using mathematical and other methods. This means that only certain key options are available, the number of which is usually well below the number theoretically possible through permutations . The mathematical regularities occurring in the license keys are used by crackers to program so-called key generators (short: keygen ) that generate new (illegal) keys at the push of a button. In addition, functioning keys can be used for an unlimited number of installations, which virtually nullifies the protection if the CD key was passed on with the copied installation files. On warez pages, (allegedly) working codes are also published as serialz .
Therefore, many manufacturers have switched to using the license key and specific hardware features of the respective computer to carry out a product activation or an online check of the license key, which checks whether the license used is still free. If not, abuse is assumed and use of the program is prevented. Some programs require an internet connection every time the program is started; most only require this during installation.
Sometimes manufacturers can also block valid keys temporarily or permanently if there is a legitimate suspicion of abuse, such as when cheating in games.