A key generator (key-gen) is a computer program that generates a product licensing key, such as a serial number, necessary to activate for use a software application. Keygens may be legitimately distributed by software manufacturers for licensing software in commercial environments where software has been licensed in bulk for an entire site or enterprise, or they may be distributed illegitimately in circumstances of copyright infringement or software piracy. Illegitimate key generators are typically distributed by software crackers in the warez scene and demoscene, where keygens are often accompanied with chiptunes and artistic visual representations.
Many programs attempt to verify or validate licensing keys over the Internet by establishing a session with a licensing application of the software publisher. Advanced keygens bypass this mechanism, and include additional features for key verification, for example by generating the validation data which would otherwise be returned by an activation server. If the software offers phone activation then the keygen could generate the correct activation code to finish activation. Another method that has been used is activation server emulation, this patches the program memory to use the keygen as activation server.
