SHSH blobs are signatures for firmware released by Apple for all devices since iPhone 3GS, iPad 1, iPod touch 3G and Apple TV 2G. If you don’t have a saved such signature before upgrading to a new iOS it will be impossible to restore your device to an older version. There are several ways to find and/or save your SHSH blobs automatically, but the best way to do it is to install Redsn0w’s Cydia, which will record all SHSH blobs every time you launch the app.
The following is a step-by-step guide on how to backup and save iPhone SHSH blobs using: Redsn0w’s Cydia and a Windows computer.
Go to your computer’s desktop and create a folder called Pwnage. Download Redsn0w 0.9.9b1, place it in the Pwnage folder and extract the zip file in the very same folder. Launch the redsn0w .exe file you find in the extracted folder. It is advised you run the application in Administrator Mode for Windows 7.
In the window that opens select the Extras button, instead of Jailbreak. You will be prompted to a list of extras featuring several options. In this case you need to click the SHSH blobs button.
The SHSH blobs button will open a new menu that features several options related to these firmware signatures. Click Fetch to retrieve “whatever blobs are on the device and submit them to the Cydia server”.
Next step requires you to connect your iPhone. Turn it off before clicking the Next button. This is the first step to enter the device in DFU mode. Follow the steps requested when displayed:
Hold down the Power (corner) button for 2 seconds
Without releasing the Power button, also hold down the Home (bottom center) button for 8 seconds
Without releasing the Home button, release the Power button but keep holding the Home button for 15 seconds
The steps you just followed will send your iPhone in reboot mode. Wait for your device to finish the reboot. Once that’s done, Redsn0w will begin the actual process of fetching the iPhone SHSH blobs and send them to Cydia and its servers.
If the process was a success, you will see a message that reads “Cydia server accepted x blobs pulled from this device”, and information about your device. Click Back in that window.
In the prompted window, click on the SHSH blobs button and then Query to verify if Cydia saved the data.
Into the ECID textfield, enter * and click OK to check everything. Once this process is done, Redsn0w will connect to Cydia and display your saved SHSH blobs. You can also find SHSH blobs in a file within the Redsn0w folder.