xyzzy is a homebrew application which originally used PatchMii to download, patch, and use a version of IOS to extract the OTP Encryption keys. The current mod now disables HW_AHBPROT, so it doesn't install an IOS anymore nor does it use PatchMii. It also supports USB devices, newer Wiimotes and GameCube controllers.
xyzzy extracts the OTP and SEEPROM encryption keys of the Wii and the vWii. They are stored in SD://keys.txt, and the device certificate is stored in SD://device.cert (or on a USB device if selected). On the Wii U, the ancast image is also dumped.