Digital Signature Utility Class

I need a C# class or classes which can be used to calculate a digital signature for a string of data. I dont know enough about this to provide great detail, but here's the general idea. public class MyDigSig { public static string CalculateSignature( string SNKfileName, string data) {...} // this returns a signature for the data public static bool IsSignatureValid( byte[] publicKey, string signature, string data) {...} // this return true if data and sig match } I'm not sure the best way to do this. I am assuming that i will create a signature using the .NET [login to view URL] tool with the -k option and i will provide the filename to the calculate method. Then i guess i will need to figure out how to get the public key out of that file, so i can compile it into my client app. ## Deliverables 1) Complete and fully-functional working program(s) in executable form as well as complete source code of all work done. 2) Deliverables must be in ready-to-run condition, as follows (depending on the nature of the deliverables): a) For web sites or other server-side deliverables intended to only ever exist in one place in the Buyer's environment--Deliverables must be installed by the Seller in ready-to-run condition in the Buyer's environment. b) For all others including desktop software or software the buyer intends to distribute: A software installation package that will install the software in ready-to-run condition on the platform(s) specified in this bid request. 3) All deliverables will be considered "work made for hire" under U.S. Copyright law. Buyer will receive exclusive and complete copyrights to all work purchased. (No GPL, GNU, 3rd party components, etc. unless all copyright ramifications are explained AND AGREED TO by the buyer on the site per the coder's Seller Legal Agreement). ## Platform C# 2.0