serial key validation in C#

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C#

I completed my project in C#.Net. I Added a serial key in it. At the time of installation it asks me for the key. The key format is also given by me, but I don't know how to validate that key.
Please give me some way how to validate that key.
Now my key is validated by visual studio or I don't know who. How is the key's validation done?
But I want to do the validation by my own. Is it possible? And if yes, how?




i added the customer information dialog. and format is given by using the serial number template. but for validation it create the problem that visual studio & its logic is so simple & it is if the some of digits is divided by 7 then key is valid.so i want to use the my logic like use sha1,MD5 so where i have to do coding. The design of the customer info dialog is not show,if it is shown then i do the coding on validate button. But now what i have to do?


Please help me.
Lots of thanks.