I am developing a shareware c# application which accepts a serial key generated in my website.
I am following the following approach suggested by Joseph Spiros
You bundle your public key with the application. When the user buys the application, they supply their name and e-mail address. The web site hashes the user's name and e-mail address, signs the hash with your private >key, and provides the result in Base64 to ease typing. When the user enters the "code" into your application along with their name and e-mail >address, your application can verify that it was signed by your private key (which only >you/the web store has access to), and that it matches the name and e-mail provided by the >user.
My website runs on linux server so that the program generating the licence will be written in php. The software is developed using c#. Please tell me whether the licence/hash generated and signed using a private key in php will be compatible with the public key in C#.
A pointer to an example would be helpful.
Have a look at the Shareware Starter Kit for an example of licensing shareware on a Microsoft stack.