xyzzy is a homebrew application which was meant as a replacement for the Tweezer Attack. It originally used PatchMii to download, patch, and use a version of IOS to extract the OTP Encryption keys for the Wii. 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. It can also extract the SD IV, MD5 Blanker and MAC address of the Wii. 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.