what is the way to generate serial keys and validate them at the time of installation in c#.

Question

what is the way to generate serial keys and validate them at the time of installation in c#.
please tell me way to check the serial key at the time of installation and suggest where to write code for it.
during making setup of project we have to maintain that record of serial keys.
All these should be  wrote in source code as code will not shown to user.
please reply.
thanks .