When Apple closes the firmware signing window for iOS 8.3, users wishing to downgrade (or upgrade) to iOS 8.3 won’t be allowed to do so. Instead, you’ll have to settle for whatever firmware Apple is signing, which is usually the latest and greatest out there.
When that happens, it’s quite probable that it could spell the end of jailbreaking for a while—remember we just got out of a significant lull.
With this in mind, the ability to downgrade back to iOS 8.3 is very desirous for would-be jailbreakers. While there is no confirmed downgrade ability just yet, there are some things that you can do to ensure that you have the best chance to downgrade should that ability arrive.
This is accomplished by saving your iOS 8.3 SHSH blobs.
To save your SHSH blobs and prepare for a possible iOS 8.3 downgrade, you’ll need to use TinyUmbrella to do so. I’ll show you how in this post and video.