Apple has added extra security features in iOS 5 that will make it much harder for hackers to safely jailbreak their iPhones, according to the high-profile jailbreakers at Dev-Team Blog. Apple’s changes will make it harder to roll back to an older version of iOS if jailbreaking goes bad.
Apple has been attempting to stop jailbreakers from altering its iOS software for years, but the U.S. copyright office came down on the side of jailbreakers last July. Users can jailbreak their iPhones and iPads to add new features, run unapproved apps or make the devices work on unofficial carriers. Earlier this month, hackers claimed to have already figured out how to jailbreak iOS 5.
The process of jailbreaking has always been a little tricky. When a jailbreak goes wrong or a hacker simply wants to revert to an older version of iOS, they could do this by saving what are known as “SHSH blobs” and use those blobs to downgrade the software without iTunes noticing. But iOS 5 makes this process nearly impossible.
The jailbreakers at Dev-Team Blog have been hacking their way though the iOS 5 beta and noticed Apple has added a feature called “APTicket” that resets the SHSH blobs each time the phone is rebooted. This will make it essentially pointless to save old blobs and try to use them to roll back the software.
The Dev-Team Blog notes that this is just for iOS 5, so restoring to builds before 5 should be fine to roll back to. But anyone that makes the leap to iOS 5 should be warned that once they upgrade, it may be a heck of a lot harder to go back.