If you have .NET 3.5 or higher avalible, you could use the
Aes Class.
Of course you will also need teh Key used fro Encryption and know the exact version of Aes that was used for encryption.
Let's talk about MVVM: http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/b1a8bf14-4acd-4d77-9df8-bdb95b02dbe2 Please mark post as helpfull and answers respectively.