With Cydia currently not giving new users the ability to save their SHSH blobs it seemed like a good time to go over how to save your SHS blobs with an alternative, TinyUmbrella. An SHSH blob or ECID SHSH is basically a unique signature which is checked against Apple servers whenever you decide to restore the firmware on iPhone, iPad and iPod touch. Once a new firmware is released, Apple stops signing the older firmware, hence making it impossible to restore back to the older firmware from iTunes. So, YOU MUST SAVE YOUR SHSH WHILE APPLE IS CURRENTLY SIGNING THEM.
Now to “why is it important to save your SHSH blobs”: The creator of Cydia has setup a new server which basically mimics Apple’s verification server and can save your older signature (SHSH blob) so that you can downgrade or restore back to the older firmware. This is important because if you don’t have your SHSH blob saved, and accidently update to new firmware, you’ll loose your jailbreak and furthermore, you wont be able to downgrade back to older firmware to re-jailbreak your device.