.Net Framework Cryptography -- Frequently Asked Questions

Check this link for Cryptography Overview

http://msdn.microsoft.com/library/default.asp?url=/library/en-us/cpguide/html/cpconnetframeworkcryptographymodel.asp

With the classes in the System.Security.Cryptography namespace contains classes you can do a lot of crypto things both symmetric and asymmetric cryptography, create hashes, and provide random number generation.