Apple will not allow users to roll their iPhone back to previous iOS versions so as to prevent them from jailbreaking the smartphone, the iPhone Dev Team suggests.
Apple will implement the new security feature as soon as the iOS 5 has been launched, but there is also a piece of good news in there. Users will be able to jailbreak for life all their current Apple products even after the arrival of iOS 5, Nexus404 reports.
iOS users can currently downgrade their operating system using saved SHSH blobs, but Apple is planning to prevent its customers from restoring previous OSes via iTunes even if they have saved the SHSH blobs.
The tech giant will modify the role of the APTicket and change it every time users perform a restore. The APTicket authentication will be required during every boot, not only during restore operations. Apple is the only one that has "the crypto keys to properly sign the per-restore APTicket” which makes replayed APTickets ”useless”, the iPhone Dev Team explains.
The limera1n exploit occurs before the APTicket is checked, which means that tethered jailbreaks will still "always be possible for devices where limera1n applies”.
All in all, this is clear proof that Apple is beginning to show its teeth to the jailbreak community.