Even if CNG is replacing CryptoAPI there is still new stuff, well wrappers, being added. This is important, for Windows users, since CNG is only available in Windows Vista (and later OS). Since Mono does not support CryptoAPI (even on Windows) all the classes with a CryptoServiceProvider suffix are wrappers around managed implementations of the same cryptographic algorithm. New CSP crypto classes Wrapper around ---------------------- -------------- AesCryptoServiceProvider RijndaelManaged [1] SHA256CryptoServiceProvider SHA256Managed [mscorlib] SHA384CryptoServiceProvider SHA384Managed [mscorlib] SHA512CryptoServiceProvider SHA512Managed [mscorlib] [1] Not a true wrapper but a copy of the source. This is required since AesManaged is available in Silverlight 2.0 (and RijndaelManaged is not available in mscorlib).