CCTalk encyption

I'm looking for someone who can provide an implementation of the CCTalk BNV encryption protocol for serial communication with hoppers and bank note validators that use this scheme. The implementation can be in C# or C++. We simply need a class that will perform the encryption and decryption of a CCTalk packet using the 6 digit BNV key. Note that we already have a complete, unencrypted CCTalk implementation in place, we simply need to 'plug-in' code that will encrypt and decrypt the packets. Note that you MUST have the documentation or the technical knowledge of the encryption scheme to complete this project. The documentation cannot be provided under any circumstances as it is under an NDA.