If you have a modded Wii U, you can dump your console’s OTP (One Time Programmable) memory to generate a keys.txt file. Tools like dumpling or Wii U USB Helper (when used with your own console) can extract your specific keys.

: This format consists of extracted folders containing code , content , and meta directories. It is already decrypted. No title keys are required.

: These are unique 32-character hexadecimal strings for specific games.

Files ending in .wud or .wux are encrypted and will not launch without the correct key present in your keys.txt file.