What is an SHSH Blob?

It is something that is mentioned a lot on iDB throughout our jailbreaking tutorials and other jailbreak-related news. “Make sure you save your SHSH Blobs before you update,” is a pretty common saying around these parts. We’ve been asked several times lately what it is, so I figured I’d post it.
An SHSH Blob is basically what Apple uses to verify the version of iOS you are running. That’s why we tell you to save your SHSH Blobs before upgrading your firmware on your iDevice. Otherwise you might not be able to downgrade to a previous version in the event you needed to.

That is unless you managed to save your SHSH Blobs with a program like TinyUmbrella. Doing so will allow you to trick iTunes, into thinking you are running an older version.

“Cody, why can’t these SHSH Blobs just be downloaded like everything else?”  Your SHSH Blob is device specific. It uses the ECID (Exclusive Chip ID) of your device, along with a challenge key, as part of the authentication process with Apple.

Because that key is static (doesn’t change), and you’re using the same ECID, it is possible for you to save your own SHSH blob for later use. It can then be used to downgrade your iDevice if you accidentally update your firmware and there’s no jailbreak available.

Now make sure you save you SHSH blobs. If you don’t know how, this tutorial will show you how to.
So is anyone as confused as I am? Just kidding. I tried to keep it pretty simple. Does anyone have anything to add or have questions? Sound off below!

With the release of Spirit now imminent, it would be a good thing to save your SHSH blob, in case you need to downgrade in the future. Saving your iPhone SHSH is very simple.
Step 1: Download Firmware Umbrella from here.
Step 2: Launch Firmware Umbrella and plug your iPhone in.
Step 3: Click “Save My SHSH” and wait for Firmware Umbrella to do the job.
Done! A copy will be saved to your computer and it will also send a request to Cydia to save your SHSH on Saurik’s server.

TinyUmbrella Updated Again, Adds iOS 4.3 and iPad 2 Support

Now that the official version of iOS 4.3 has been released, @notcom has released an updated version of TinyUmbrella to support the new firmware.

In addition to iOS 4.3 support, the updated TinyUmbrella (version 4.30.00) also brings iPad 2 support for all models (WiFi, CDMA, and GSM), and a new tweak requested by the creator of Cydia, @Saurik. Notcom also mentions that users who do not update to the latest version of TinyUmbrella, may experience significant slowness when saving their SHSH blobs in the future…

TinyUmbrella now supports all three new models of iPad 2. I’ve also added a much-needed tweak per saurik’s request. If you don’t update to the latest version, you may experience /significant/ slowness when saving your SHSHs in the future. With this release, 4.3 is supported. I plan on making some changes to the UI to help out the poor saps stuck on vertical resolutions < 900. I’m also going to be removing the proxy section of the app and simply using the system proxy settings.

As a reminder, to save your SHSH blobs, simply connect your iDevice via USB to your computer, launch TinyUmbrella, and click the “Save SHSH” button.

You can download the updated version from here.