原帖由： Brad ,
If your iPhone is still on 4.3.3, you can still restore to 4.3.3 if you use program iFaith. iFaith will save the SHSH of the firmware that is on the iPhone. You can only Restore to the firmwares you have SHSH for, or the ones Apple is signing. For the iPhone 3GS Apple is still signing Firmware 4.1, you will need to use TinyUmbrella to Exit Recovery after it is done. Custom Firmwares are created with Pwnage Tool or Sn0wBreeze, but you can only install the Custom Firmware you have SHSH for or that Apple is signing.