iSHSHit is a new cydia tweak that lets you save and backup SHSH blobs on your iPhone, iPod or iPad itself. You can also send your saved SHSH blobs via email using this cool app.
Moreover, it automatically uses the Cydia On-File service in the background to store your SHSH on Cydia servers.
iSHSHit is available through BigBoss Respority in Cydia Store. After jailbreak, run cydia and search for iSHSHit to install it. After the installation is done, you will find the iSHSHit app on your iPhone springboard. Launch the app.
Now tap on save and iSHSHit will get the blobs from Apple servers and save it on your device.
Here is the official description of the app:
iSHSHit allows you to back up device firmware SHSH blobs from Apple directly on your device for later downgrading. It automatically uses the Cydia On File service in the background, so it’s a great way to ensure that your SHSH is stored by Cydia. iSHSHit can also email your SHSH blobs to you for more permanent storage.
Note: You can also save SHSH blobs of your iPhone using TinyUmbrella, a desktop application.
Can I save shsh to higher version
With the knowledge I have not upgrade iPhone
You can save the SHSH for that iOS version which you are using at that time.