Add CSS decryption

Enums.cs

@@ -0,0 +1,12 @@
+namespace Aaru.Decryption
+{
+    public enum DvdCssKeyClass : byte
+    {
+        DvdCssCppmOrCprm = 0, RewritableSecurityServicesA = 1
+    }
+
+    public enum DvdCssKeyType
+    {
+        Key1 = 0, Key2 = 1, BusKey = 2
+    }
+}