If you updated to i OS 7 from i OS 6, and are now suffering from motion sickness or acute day-glowitis, I have bad news: You can no longer downgrade from i OS 7 to i OS 6. This is partly for security reasons, but mostly because it’s simply part of the Apple experience: By buying an i Phone or i Pad, you implicitly sign away your rights and privileges so that everyone can coexist in blissful unfragmented harmony in Apple’s sandbox.
(See: How to install i OS 7 on your i Device.)To understand why you can’t downgrade to i OS 6, we need to look at the i OS update and restore processes.
Basically, after you install a new version of i OS — either over-the-air on your device, or via an IPSW file in i Tunes — your device phones home to Apple.
Apple then checks to see whether the newly installed version of i OS is signed — as in, the cryptographic signature of the files matches a list of approved signatures on Apple’s servers.
This serves three purposes: First, it makes sure that none of your files are corrupted or infected with malware; second, it ensures that you’re only running an approved version of i OS; and third, there’s the small point of fragmentation.
This is why you will read some reports of people being able to downgrade from i OS 7 to i OS 6, but why none of the guides you find online will work.
The one exception is if you have a jailbroken i Phone 4 and previously backed up the SHSH blob (the signature token sent by Apple) for i OS 6 — in which case, you can downgrade to i OS 6.
For any i Device based on the A5 So C or newer (the i Phone 4S, i Phone 5, i Phone 5s, i Pad 2 or later, i Pad Mini, and the fifth-gen i Pod Touch), you cannot downgrade — and probably never will be able to, unless hacking groups like the i Phone Dev Team and Evad3rs can find a really low-level jailbreak.
One of the strongest features of Apple’s mobile ecosystem is that every device runs the same operating system.
If users could downgrade freely, then the story might be very different.
Basically, during the grace period, Apple’s servers still accept the signature of previous versions of i OS (i OS 6.1.3 and 6.1.4 in this case) — and then, when that period ends, only the latest version is accepted (i OS 7).
If your version of i OS doesn’t match Apple’s approved list, your device will refuse to work until you reinstall an approved version (i OS 7 in this case).