Tried updating my jailbroken iphone
In order to enforce this limitation SHSH blobs were introduced, which is a hash signature system.
Although this is getting technical, an SHSH is created by an SHSH formula with 3 or 4 TSS keys (say with me).
In the early days you could downgrade your i OS device to any firmware version you wanted to and not run into many troubles.
This is because firmware restores never had to be approved by Apple, but starting from i OS 3.0 onwards Apple implemented a technology called You see, when you restore your i Phone, i Pod Touch or i Pad through i Tunes your device phones home and ensures that it is allowed to be restored to a specific firmware version.
Simply scroll through our section for the firmware version you are trying to downgrade to, and read one of our easy to follow how to guides on downgrading your i Phone, i Pod Touch, i Pad, Apple TV or even Play Station.If you still have a problem, you’ll need to reset the device as new and then restore it from the backup you made.