Jailbreaking Basics: What are SHSH blobs and why/how to save them

What are SHSH blobs?

SHSH blob is shot form of Signature HaSH blob made by Apple to restrict downgrading of iOS firmware. It is a plist of different blobs, where each blob represents a specific part of software or hardware. Apple generates these SHSH blobs when a device tries to restore the device to a particular firmware. When we say that Apple  has stopped signing the firmware, we mean that Apple is not generating SHSH blobs for the particular iOS version. During the process of restore, iTunes sends a part of firmware along with some hardware info. If it gets a SHSH blob in return, then the device is restored. If not, then iTunes gives a error and does not allow to restore.

Two things before going further  – Firstly, SHSH blobs are no way related to baseband upgrade/downgrade. This is a common myth that SHSH blobs, if saved, can be used to downgrade baseband. There is currently no known process to downgrade baseband. Secondly, SHSH blobs should be saved whether or not you plan to jailbreak your iPhone/iPad etc.  SHSH blobs are not related to jailbreak, but related to firmware downgrade. Saving SHSH blobs is beneficial for both jailbroken as well as non jailbroken users.

Why to save SHSH blobs?

Saving SHSH blobs allows user to downgrade firmware without any restrictions. You can downgrade any time, which is beneficial for everyone, and especially for people relying on unlock. However, baseband is never downgraded no matter if you save SHSH or not.

How to save SHSH blobs using tinyumbrella?

1. Download TinyUmbrella from http://thefirmwareumbrella.blogspot.in/. Availbale for both Mac and Windows
2. Open TinyUmbrella and connect your apple device. You will be presented with some warnings. Click OK on both
3. In the left hand column, you will see all the connected iDevices (iPhones, iPads, iPod Touch etc)

   

4. Goto Advanced as select only the options listed below

   

5. Click save SHSH.

SHSH would now be saved locally on your PC. Happy Blob Saving!!!

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