Even though Comex delayed the release of Spirit, we know that we're just a few days away from the official release date. Spirit will sure be able to jailbreak your iPhone, iPod Touch and iPad, but the exploit used will most likely be patched in a matter of days by Apple.
To protect yourself in the event of an "accidental upgrade" to a newer firmware which would make you lose your jailbreak, you will have to save your SHSH blobs.
What is SHSH and why save them?
Taimur gave us a pretty good description of what SHSH are and why they are important:
"So first up, what exactly is SHSH blob or ECID SHSH? Well, it is basically is a unique signature which is checked against Apple servers whenever you decide to restore the firmware on any of your iDevice (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.
Now to “why is it important to save SHSH blob”: 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 accidentally 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."
The Dev Team warned us yesterday about the consequences and gave us simple directions on how to save our SHSH. There are 3 ways to do that:
If your iPhone is already jailbroken, you can save your SHSH on Saurik's server. If you're not jailbroken yet (ie. you have an iPad), you can use Firmware Umbrella to create a local copy of your SHSH blobs As an alternative to Firmware Umbrella, you can use autoSHSHNote that saving or backing up your SHSH blobs is not vital or mandatory. It's just a safety step that will allow you to restore or downgrade should something go wrong in the future.