Originally Posted by Olethros

There will be no way to revert from the tethered jailbreak without restoring to OS 3.1.3 which will kill your ability to jailbreak for the immediate future.

Just activated it and I saw iTune downloaded OS 3.1.3... I understand if I click "Update" now it will get my ipod go up to 3.1.3 but what happened if I click "Restore"? Would it also upgrade the OS or restore to original version? If it can restore to original OS version can I also restore to 3.1.2 using this method after JB it?

Originally Posted by Ker0r0

Just activated it and I saw iTune downloaded OS 3.1.3... I understand if I click "Update" now it will get my ipod go up to 3.1.3 but what happened if I click "Restore"? Would it also upgrade the OS or restore to original version? If it can restore to original OS version can I also restore to 3.1.2 using this method after JB it?

Yes restore will load 3.1.3

You need to option-click (shift-click) restore and point to a 3.1.2 ipsw ifvyou need to reload the OS.

If you have a 3rd gen iPod touch, you need SHSH to restore so as Apple has now stopped signing 3.1.2 you must be very careful to avoid requiring a restore as your only option on a 3rd gen is to restore to 3.1.3

Yes, my iPod Touch is a 3rdG....

So if I JB it, it better no need to restore, otherwise, it can only be restored to 3.1.3 because I don't have a saved copy of the 3.1.2 SHSH stuff.

Is it possible to simply save a copy of the OS patition? No way to backup / restore the OS partition of iPhone3GS/IPT3 without iTune?

Originally Posted by Ker0r0

Yes, my iPod Touch is a 3rdG....

So if I JB it, it better no need to restore, otherwise, it can only be restored to 3.1.3 because I don't have a saved copy of the 3.1.2 SHSH stuff.

Is it possible to simply save a copy of the OS patition? No way to backup / restore the OS partition of iPhone3GS/IPT3 without iTune?

The iPhone hardware will only allow a restore for each file with a corresponding signature hat is signed both by Apple (private certificate, only available to Apple) and with the unique ECID from your device. This includes the OS partition.

This check is in hardware when you use dfu mode, there is no way to bypass that.

When you use recovery mode if there is an iboot exploit it is possible to patch out this check in software for all but the lowest level part of the boot process (this is the tethered jailbreak)

Once the SHSH checks are patched out you can send unsigned files like an OS image. However because there is currently no way to patch out the SHSH checks for the Low Level Boot part it is not practical to use tools like pwnagetool to load a custom ipsw, this will not work.

There are no public iboot exploits for the iboot that ships with 3.1.3 so both recovery and dfu mode are closed to jailbreak.

Just for the discussion... I suppose you can backup/restore root partition/file system in a JBed running device? That is what I am thinking of to recover a messed up JBed device to it's original new JBed state in case things go wrong in a later stage and you cannot use the official "Restore" process.