Restore ipod without updating mac
Whenever you upgrade or downgrade your i Phone, i Pod Touch or i Pad, new SHSH blobs have to be generated because one of the parts to the SHSH formula is the firmware version.In order to prevent firmware restores Apple only signs one firmware version at a time, which is obviously the latest firmware version available.In case this wasn’t a big enough limitation to downgrading i OS devices, in the i OS 5 firmware generation Apple introduced yet another technology to prevent downgrading called APTickets.What APTickets are is essentially the next generation of SHSH blobs.Once you have your SHSH blobs signed, as stated previously, if you upgrade to a new firmware version and decide you don’t like it you can downgrade back to the firmware version which you have saved SHSH blobs for.
This is essentially performing a replay attack, in the fact that data is being fraudulently retransmitted.
Note #1: This is not some magical section of guides that will allow you to downgrade your i Phone, i Pod Touch, i Pad or Apple TV 2G without having your SHSH blobs saved for prior firmware versions.
Meaning you had to have saved your SHSH blobs for the firmware version you are trying to downgrade to, or downgrading will not work.
Newer devices like the i Pad 2, i Pad 3, i Phone 4S, i Phone 5 and i Pod Touch 5G has different restrictions however, because they are not vulnerable to the limera1n exploit and are governed more-so by APTickets.
These devices can only be downgraded on the i OS 5 firmware generation and require saved SHSH blobs and APTickets for the i OS 5 firmware version you are currently running and are trying to get to.
In the future APTickets will completely replace SHSH blobs, this will happen once the i Phone 4S stops being supported.