ECID field, downgrades no DICE

Apple added a new piece of security to the iPhone 3GS. I was sending the applelogo to the phone and it kept giving me "Memory Image Not Valid". Puzzled, since I knew iTunes sent this no problem, I dumped the USB communication. Seen that new thing, "Verifying iPhone restore with Apple"? It adds another tag to the img3 file inside the sig checked area, called ECID, which contains a unique id for the phone. INSIDE THE SIG CHECKED AREA. Then the server resigns and sends you a new signature. Basically it generates a custom Img3 which only works on your specific phone.

This is bad news... They almost surely won't authorize downgrades on new phones. They might not even authorize downgrades on older phones. Get a usb dump of a restore to 7A341 if you ever want to go back(which you may need to use exploits). Unless of course it's broken deeply at the hardware level. Then lol @ Apple.