mono/mcs/class/System.Core/System.Security.Cryptography/README.CSP

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).