It’s pretty simple to downgrade your iphone to 1.1.1

A/ Put your iPhone on DFU mode (using Ziphone)
B/ In iTunes hold the shift key and click on ‘Restore’

C/ Pick the 1.1.1 firmware file on your computer (if you don’t have it, download 1.1.1 iphone firmware) and press ok
D/After about 4 minutes you will get an error (That’s OK)
E/ Close iTunes
F/ Download Iphuc
G/ Type each of these commands on their own line and hit enter for each:

cmd setenv auto-boot true

cmd saveenv

cmd fsboot

exit

H/ Wait a few seconds and your iPhone should be out of DFU mode and at the activation screen.

Put iPhone in DFU mode: With iTunes still open and the iPhone still connected, press and hold the Sleep/Wake button and the Home button until the screen turns black. Once it does, let go of the Sleep/Wake button. Continue to hold the Home button until iTunes displays a pop up about the iPhone being in recovery mode. Click OK.