To downgrade iOS firmware, you must have already saved SHSH blobs of ipsw for which you want to restore your iOS device to. A backed-up SHSH blob protects you in the event of an “accidental upgrade” to a newer firmware which would make you lose your jailbreak. These blob certificate file act as a life saver to downgrade your firmware.

SHSH blob is a backup file with the signature needed to restore to a specific firmware version. This signature is verified by Apple while restoring your device to lower firmware. Therefore it is highly recommended to save the signature file for your device as long as Apple issues it. As soon as a new firmware is released, Apple stops signing the older firmware, making it impossible to restore back to the older firmware.

Devices that need Apple signatures are: iPhone 3GS, iPhone 4, iPhone 4S, iPod touch 3G, iPad, iPad 2, iPad 3 (The New iPad), iPod touch 4G, Apple TV 2G and all newer devices. The iPhone 3G and iPod touch 2G bootroms do not require these SHSHs.

It is not necessary to jailbreak the device for taking backup of SHSH blob files. Usually the SHSH signature file is stored on Saurik’s server. If it is stored there, then you can see in the top of Cydia on jailbroken devices.

iOS users often make a big mistake thinking that the SHSH firmware version they back up depends on the firmware version they have installed on their iPhone, iPad or iPod touch. This holds good for iH8sn0w’s iFaith tool since it dumps the SHSHs from your device’s storage whilst TinyUmbrella gets SHSHs from Apple’s servers. Here’s how you save SHSH blobs:

Since iOS 5.x accommodates APTickets that are crypto-verified before submitting to Cydia, just like the main blobs. TinyUmbrella TSS Server procedure does not work when restoring to any version of iOS 5. Saving SHSH files is bit tricky, you need to create and restore to a custom IPSW with stitched SHSH blobs. Here’s how you save SHSH blobs.

Once you have saved SHSH blobs file with you, you can follow the guides to downgrade to lower firmware. Once your iOS device is downgraded you can re-jailbreak your iPhone, iPad or iPod touch.

How to Downgrade iPhone 4, 3GS, iPod Touch 4G and iPad 1G

How to Downgrade iPhone 4, 3GS, iPod Touch 4G and iPad 1G