hacker and sn0wbreeze developer iH8sn0w is working on a new tool SHSH blobs Extractor that will allow you to extract the old SHSH blobs signature files, even if Apple stops signing older firmware files.
According to iH8sn0w, the blobs are always available on firmwarebecause the boot chain relies on these unique blobs. It is basically another signature check of Apple but is given to the device originally from Apple via a Restore/Update.
If you have a device that is on a firmware that Apple is not signing (example: 4.1), and you wish to grab blobs for, you can with the new upcoming tool. Just ensure that you don’t press that Update/Restore button in iTunes. Everytime you restore or update, these blobs get replaced by completely new SHSH blobs for the firmware you are updating/restoring to. Via iDeviceDaily
What are SHSH Blobs? How it is different from TinyUmbrella?
SHSH Blob are signature file which is checked against Apple Server to authenticate that your is running on the latest version of iOS. If you try to restore your device to a previous version, Apple won’t allow you because you are trying to load an older version of iOS. To do so, we need to send a request to a different server (Local or designated) which sends SHSH blob signature files (which were saved by you) back to iTunes faking that its the current version. TinyUmbrella works in this way.
Unlike TinyUmbrella, SHSH Blobs Extractor utility saves your old SHSH blobs (even if Apple stops signing old ECID SHSH), so that you can rerun the jailbreak on your iPhone, iPod Touch or iPad incase you unintentionally upgrade to the future firmware releases by Apple. It is always advisable to grab or take back up of Blobs [ECID SHSH] on current installed iPhone iOS firmware.
Why is it important to save SHSH blobs?
Saurik has setup a new server which imitate Apple’s verification server and allow to save your older signature (SHSH blob) so that you can downgrade or restore back to the older firmware. If you don’t have your SHSH blob saved, and accidently update to new firmware, you are bound to lose unlock as well as jailbreak you won’t be able to downgrade back to older firmware to re-jailbreak your device. In order to Jailbreak your iPhone iOS again you MUST have SHSH Blobs on Cydia Server.
We will update you once the SHSH Blobs Extractor download is available.