iOS 5 beta has officially become the iPhone jailbreaking community’s worst nightmare. A post on the Dev-Team Blog has confirmed the latest build prevents both downgrading firmwares and untethered jailbreaks.
Without diving too deep into the technicalities, the LLB and iBoot stages of iOS 5 depend on the authenticity of APTicket. Since APTicket is uniquely generated at each restore (and boot), Apple alone holds the keys to properly sign a pre-restore APTicket. Bottom line: a firmware downgrade or untethered jailbreak with iOS 5 is near impossible.
One of iOS 5’s killer features is the addition of over the air (OTA) updates. A side effect of this transition is that updates will only change certain aspects of iOS 5 and not the entire OS. This means that unlike current installations, a firmware restore to a specific iOS 5.x build will not exist. Jailbreakers will be forced to use that last complete iOS 5 build, likely version 5.0.
With that being said anything is possible, especially when you factor in the determination and will power of an avid jailbreaking community. The Dev-Team has managed to jailbreak iOS 5 beta via a tethered data connection while using a previous version of iTunes, but don’t expect a long shelf life.
via Ars
