I've played around with John The Ripper before and it was able to successfully crack some personal passwords via brute force. However, in those scenarios the "unknown variable" was a password - and the known variable was the encryption method.
In the current scenario, things are a bit different. Now I have a scenario where the 2 input keys are known - and an external tool exists that can convert those binary inputs into accurate decoded outputs. As such, I can create as many test scenarios as needed of things like setting both inputs to 0x00 and seeing the decrypted results... or setting one to 0xFF and the other to 0x00 --- etc.
I've created several thousand logical combinations of inputs to try and logic my way through the output patterns, but while I can recognize that a pattern exists (and am confident that the method includes a series of bit shifting, XORs, and potentially some other modifications), I'm hitting a bit of a dead end and hoping that a software solution exists out there that may be able to help.
Thanks in advance for any suggestions!