Quote:
Originally Posted by pilotbob
Yea that why you should always back up a device before doing a major OS upgrade.
BOb
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Backups don't let you revert to previous versions of iOS. They only save your appdata and system settings.
Only jailbroken devices that have saved the SHSH blob can be reverted. The SHSH blob is a digital signature that authorizes a particular version for a specific device, and ONLY APPLE IS ALLOWED TO MAKE THEM! A jailbroken device will automatically save these, but only for iPhone/iTouch 4s and older. On searching around, I discovered a program called TinyUmbrella (
http://blog.firmwareumbrella.com/faq/) which can be manually used on ANY device even without the jailbreak. Obviously, jailbreak on iPhone 4 is better since it automatically backs up your SHSH blob.
This all does a carefully calculated nothing (Apple's fault BTW) if you didn't actually get one of those keys while Apple still signed it. And they only sign the current release, plus the previous one WITHIN A FEW DAYS OF THE LATER RELEASE!!!