We have been hearing a lot about jailbreaking tethered iPhone or tethered iPod Touch jail breaks. Ever wondered what the heck is tethered and untethered iPod touch or iPhone jailbreak?
Tethered Jailbreak
Since the launch of iPhone and iPod touch OS 3.1.2 (to be precise, iBoot version 352.3.2), there is a different way in which an iPhone or iPod touch has to be jailbroken due to a change that Apple engineers got into the booting process
iPhone / iPod touch Booting process
Power on --> Low Level Bootloader (LLB) --> iBoot --> Firmware (I believe)
RedSn0w and other jailbreaking mechanisms made use of an exploit in one of the feature of iBoot 2.1.1 which was found in 2.2 also. So RedSn()w loads itself into iBoot and gives the user the jailbroken iPod or iPhone every time he boots his system.
The Twist
From 3.1.2, the Low level Bootloader does validation of whether the iBoot is Apple made or not. Since the RedSn()w does not have the Digital Image Signature of Apple, it is refused to be loaded and hence we get the White Screen and firmware does not load.
Tethered Jailbreak : You then have to connect your iPod touch /iPhone (which has the white screen of death currently) to the laptop and run the RedSn()w firmware patch in 2.1.1 iBoot to make it run.
FAQ on Tethered Jailbreak
1) Would you lose the data due to Tethered Jailbreak
Ans : No, since we are only dealing with the bootcode (iBoot), data is safe
2) Why is it called Tethered Jailbreak
Ans : Because you need that iPod /iPhone to be bonded to the computer everytime.
3) Do we need to run RedSn()w patch if the iPhone is in sleep mode?
Ans : No
Untethered Jailbreak
The iPhone would not need the user to connect the iPod touch or iPhone to laptop and run the patch everytime he reboots the iPhone / iPod touch.
This is possible is your iBoot version is 359.3 or below. The hack method was called the 24kbpwn hack where the hackers intelligently made the iBoot crash at boot point, introduce 24kB of their own code and make iBoot believe that everything was normal.
Apple smartly blocked this exploit in 359.3.2 version of iBoot. So that is when the RedSn()w failed to do the untethered jailbreak.
FAQ on Untethered Jailbreak
1) iPhone and iPod Touch shipped from what time frame has blocked untethered Jailbreak?
ans : Since October 2009
2) Sn()wBreeze supports untethered Jailbreak. What is the problem?
ans : It does not work on MC models
3) Is there no solution for untethered Jailbreak for the latest iPhone / iPod touch 3.1.3 ?
Ans : Spirit is the answer. Click here to read more about Spirit Jailbreak