https://github.com/SuperTavor/Viola
Example
Code:
:decrypt
Viola.CLI-Portable.exe -m decrypt -i "975db12376c07780478431b25279b380.cpk" -o "975db12376c07780478431b25279b380.cpk_dec"
pause
:encrypt
Viola.CLI-Portable.exe -m encrypt -k 3810055266 -i "975db12376c07780478431b25279b380.cpk_dec" -o "975db12376c07780478431b25279b380.cpk_out"
pause
Each CPK file has its own key.
I just have 2 small sample files, so figure out the rest for yourself.