iDecryptIt

iDecryptIt is a VFDecrypt graphical user interface for Windows users. When you update your iDevice, iTunes downloads a firmware file.

If you open up the firmware, you will find many small files along with one big one. That big one is the (encrypted) filesystem. If you use iDecryptIt on the file, iDecryptIt will decrypt it. The decrypted file can then be extracted with 7-Zip or mounted as a virtual hard drive with certain tools.