DirectShow Transform Filter with simple Real-Time Decryption

Needed is a DirectShow Transform Filter decrypting an encrypted Video and Audio file on the fly. The filter should be also capable to encrypt a file with an appropriate filter graph. The cryptographic algorithm should follow a Standard algorithm but is chosen by the programmer. CPU load shall stay within reasonable Limits on a Standard PC (e.g. < 10%). Important Feature is the storage of the private key within the windows registry with a Minimum key length of 80 bit. The filter shall be placed in between source filter and splitter with automatic filter graph management covering both, Audio and Video data. The filter shall be capable to decrypt any Standard Video and Audio file, e.g. mpeg1, mpeg2, mp4, divx, xvid, mkv a.s.o. The filter shall be implemented in C++ using the Windows SDK for Windows 7 and .NET Framework 4. It shall be capable to run on Windows 7 with 32 and with 64 bit on the 32 bit subsystem. Deliverable item is a complete Microsoft Visual Studio 2012 Project. Also two filter graphs shall be delivered, one in file encryption and the other one in file decryption configuration.