When asked for an upgrade to 9.1.2 I was asked for a four digest code where is this code generated
HHow do I upgrade my software on my phone to9.0.1
iPhone 5, iOS 8.0.2
The current iOS version is 9.2.1. To update to that version, select Settings > General > Software Update, and perform the download and install there.
You will need to enter the device passcode when prompted by the update — this is the same passcode that is used to unlock the device for use — if a passcode is set on the device.