Most Important in Jailbreak: Save SHSH Blobs

There is one thing that is often overlooked in the iPhone/iPod jailbreak processes, that's storing SHSH blob. An SHSH Blob (for Signature HaSH) is a 1024 bit RSA unique signature used to verify the validity of firmware on newer Apple iOS devices. SHSH provides digital signature required to validate the firmware; very important in the upgrade processes.

Apple signs their iDevice with SHSH blobs for the current iOS firmware so it's able to be upgraded later with iTunes. Saving SHSH blob for a given firmware on a specific device will allows user to restore the device to the match firmware even after Apple has stopped signing it. It’s all about the future change in the device firmware.

Doing save SHSH Blob is very useful in tricking iTunes when it does sign to validate an old firmware. This is necessary to restore previous versions of the iOS firmware on the iPhone, iPad and iPod. Doing such a manner very important in the iOS jailbreak. Without these SHSH blobs you can not restore a firmware (e.g. from a jailbroken device) which is not being signed by Apple and once Apple stops signing a firmware, you cannot save SHSH blobs for it.

There are many ways in saving SHSH blobs. Many applications are provided to do SHSH blobs save or backup. Here are 4 Different Ways in Saving iPhone's SHSH Blob.