License Key generation in C# using cryptography?

I am developing a desktop application in that i want to create a product/license key for that application. I want to use cryptography(symmetric/asymmetric algorithms) for key generation, so how could do this. In that i want to generate a public key and from that public key i want to generate a user/product specific key. Please give me solution or send me such application on my mail (pote_atul@yaoo.com).

thanks in advance,

atul pote