Thx a lot, that's calrify stuff a bit. The keygen() for dynamic key is within functions.php in the source archive and that function is in turn encrypted with this pattern value (in the file below). If that can help, I'd appreciate that:
mediafire.com /file/wv838gsq0saezgj/pattern/file
I do have some experience hacking obfuscated bytecode stuff (i.e. a squirrel language interpreter with obfuscated bytecode within a linked library to a win32 native binary), but this php obfuscation is novel to me and it's not a purpose of my current research