iOS hacker iH8sn0w has discovered a loophole in Apple’s APTicket system that has allowed him to restore his iPad 2 to iOS 5.0.1 from iOS 5.1. Apple does not officially allow for you to downgrade your iPad, iPhone, or iPod touch to a previous software update, but the Canadian hacker has found a successful workaround solution. iH8sn0w tweeted about his discovery, noting that this loophole works on all iOS devices powered by Apple’s A5 and A5X chips — that would be the iPad 2, iPhone 4S, and new iPad.
Older iOS devices powered by Apple’s A4 chip — think iPhone 4, original iPad, or the latest iPod touch — already have a method of downgrading to a previous iOS version. There has not been any mention of a public release yet for this method, but saving your SHSH blobs is a requirement and should be done so preemptively. iH8sn0w is best known for developing sn0wbreeze, a popular jailbreaking tool for iOS devices, in addition to iFaith and iREB.