Storing SHSH blob is a very important pre process before jailbreaking. It is a MUST DO process if you dont want to risk bricking your iphone and have no firmwares to revert to.
What are SHSH blobs?
SHSH blobs are specific to your device. It is nessesary for the downgrade of your iDevice through iTunes. SHSH are signatures signed by Apple. Everyime Apple releases a new firmware,they will stop signing the previous firmware. It is adviced to store your SHSH blobs frequently.
How to store SHSH blobs?
1) Download TinyUmbrella here. The developers update their program frequently,so be sure to update it.
2) Launch TinyUmbrella
3) Connect your iDevice
Select “Advance Options”
Select your device
Make sure “Request From” is set to “Cydia”
Click “Save my SHSH”
5)Your SHSH is now saved!