i will try if i can decode function.php file with dynamic key
Thanks a lot. I was able to decrypt the pattern, that is used to encrypt a keygen() function, it is "8 r 3 @ k 1stK 3y" (remove spaces and quotes). The keygen() with argument as listed in your decompile produces this result:
string(32) "c080e8a3fccb964a33b3021a48120a5a"