iOS 7 Tethered Downgrade

Preparations

We will need to do two things to prepare. We will back up some files needed to boot iOS 7 and create a tar containing the contents of the filesystem image.

We will start by decrypting the filesystem image

Keys for decryption of firmware components and proper component names can be found at The Apple Wiki

The root filesystem image is the largest dmg file inside the IPSW

dmg extract encrypted.dmg rw.dmg -k key

We will now need to convert the image to UDZO format

dmg build rw.dmg ios7.dmg

You will now have a read-only decrypted filesystem image

hdiutil attach ios7.dmg

Take note of the mount point, highlighted in the example below



We need to enable ownership for the tar to have correct ownership

sudo diskutil enableOwnership mountpoint

Now you can create the tar

sudo gtar -cvf ios7.tar -C mountpoint .

Now you will need to connect to the device to backup some files. Start off by creating an iproxy tunnel:

iproxy 2222 22

You should see "waiting for connection". Let this run in the background and open a new terminal window to transfer files

These are the files you will need to backup to your computer for booting:

Password should be "alpine"

scp -P 2222 root@localhost:/System/Library/Caches/apticket.der ./apticket.der

scp -P 2222 root@localhost:/usr/standalone/firmware/sep-firmware.img4 ./sep-firmware.img4

scp -r -P 2222 root@localhost:/usr/local/standalone/firmware/Baseband ./Baseband

scp -r -P 2222 root@localhost:/var/keybags ./keybags

Next part → Making SSH ramdisk

iOS 7 Tethered Downgrade