Decrypting in .NET 4

[Bill]

Hi, I need to write a .net program to decrypt encrypted files coming from a client, all I know is the files were encrypted using the Windows CryptoAPI technology and with some component called ProfsComponent written in Delphi. We have the private key and something called a session key (or symmetric key) that come with each of the files. How do I write a program in .NET that will be able to decrypt the file? Thank you.

[PsychoCoder]

Take a look at this walk-through on MSDN for using the Windows CryptoAPI.