Downgrade

Good news for owners of the iPhone 4S and iPad 2 looking to downgrade from iOS 5.1. iH8sn0w announced the discovery of a loophole that makes it possible to downgrade any A5 device to iOS 5.0.1. Not only this, but the developer has successfully restored an iPad 2 to iOS 5.0.1 using the procedure.

Found a loophole in Apple's apticket system. Restored my iPad 2 to 5.0.1 from 5.1. Works on all A5 devices. :)

— iH8sn0w (@iH8sn0w) March 25, 2012

Downgrading an iPhone, from iOS 5 to 4.3.3 for example, requires saved SHSH blobs since Apple stops signing older firmware when an update is released. It's likely that the loophole iH8sn0w has found will also require saved SHSH blobs to work.

Are you missing some key jailbreak tweaks now that you've updated your iPhone 4 or 3GS to iOS 5 firmware? Already tired of dealing with all of the shortcomings in iOS 5 notification center? Luckily if you have saved your SHSH blobs you can easily downgrade and return your iPhone to a jailbroken state (and reinstall LockInfo!)

In order to downgrade you must have saved SHSH blobs. Pictured above are how saved SHSH files appear for each firmware version in Cydia, when they are saved to Saurik's server. Follow these steps to downgrade to earlier firmware, including iOS 4.3.3 for an untethered jailbreak with JailbreakMe.

According to the latest research by iPhone Dev-Team Apple has taken steps to make iOS 5 more difficult to jailbreak and downgrade. Although the limera1n exploit used for iOS 4.x jailbreaks still works in beta iOS 5, only a tethered jailbreak is possible at this time. Starting up a jailbroken iPhone tethered requires that the device be connected to a computer while booting.

It's not clear if Apple's move can be countered in the near future, as the company will begin to generate a unique APTicket every time the iPhone is restored. Not only this, but the APTicket will be verified every time the device is turned on.

Sometimes for whatever reason an iPhone firmware upgrade ends up being counterproductive or causes issues with your individual phone. Maybe you're experiencing battery life problems with iOS 4.1 on your iPhone 3GS. Updates can even happen by accident with the wrong click of a button, wiping a jailbroken device.

If you have already saved your SHSH files for one or more earlier firmware versions on Saurik's server, you can follow these steps to downgrade from iOS 4.1.