SHSH blobs or ECID SHSH is a unique digital signature that Apple assigns to each iPhone, iPod Touch and iPad.

Whenever you connect your iPhone 3GS or iPod Touch 2G/3G or iPad to iTunes to restore or update iPhone OS firmware, the ECID is sent to Apple servers for authentication and iTunes will proceed to restore the device only if the ECID authentication is complete. 

However, when a user installs the new iPhone OS firmware, the digital signature associated with the earlier firmware is erased. This makes it difficult to restore the iDevice to its earlier firmware. 

Saurik, the creator of Cydia has setup a server, which basically mimics Apple’s verification server so that you can downgrade or restore back to the older firmware by making use of the SHSH blobs.

If you have jailbroken your iPhone 3GS, iPod Touch 2G/3G or iPad then this is important because you might want to restore your iPhone to an older firmware if the newer version includes patches that plug the loopholes used to jailbreak the iPhone OS. As you might know, it took the iPhone hacking community, more than two months to release the software tools to jailbreak iPhone OS 3.1.3. So MuscleNerd of the iPhone Dev Team has strongly recommended users to take a backup SHSH blob to future proof it for jailbreaking. 

This tutorial will take you through the step by step instructions to backup your ECID SHSH or SHSH blobs of your iPhone 3GS, iPod Touch 2G/3G and iPad. Please note that this can be a time consuming process if you don't know your ECID.

Please note that this guide is for Windows users only. If you are a Mac user, you can checkout our step-by-step guide for Mac users.

Step 1: Click here to download the latest version of Firmware Umbrella to your computer desktop.

Step 2: Right-click the downloaded ZIP file and select 'Extract All' to extract the files to your desktop.

Step 3: From the 'Start' menu, navigate to Programs -> Accessories 

Step 4: Right-click the Notepad application and select 'Run as administrator' from the contextual pop-up menu. Confirm the selection by clicking the 'Yes' button.

Step 5: From the desktop, navigate to My Computer -> C: -> Windows -> System32 -> drivers -> etc. Double click and open the 'hosts' file.

Step 6: Look out for a line in the file that reads 'gs.apple.com'. If found, remove the line of code. Save the file and exit

Step 7: You will need Java installed on your system to proceed to the next step. Click here to download Java if you do not have it installed on your system already

Step 8: From the desktop, open the extracted Firmware Umbrella folder and launch the Umbrella.exe application.

Step 9: You will now be prompted to input your device ECID, version and to select a SHSH repository

a. If you do not know your device ECID, download the USBview application by clicking here. You need to then put your iPhone in recovery mode (you can check this tutorial) and launch USBview.exe. If you are putting your iPhone in recovery mode, please do not forget to take a backup of the contents on your iPhone. You may refer to this article for a helpful guide on backing up your device.  

Select Options -> Config Descriptors and then press the F5 key to refresh. From the USBview left pane, click on 'Apple Recovery (iBoot)'and copy the ECID key from the right side pane.

b. In the SHSH repository, select 'Saurik-Cydia' from the dropdown menu. This will check Cydia for SHSH and in case it doesn't exist, it will be stored there. Alternately, you may also select 'Apple' to query Apple for your SHSH.

Step 10: Press the 'Submit' button. You will be displayed a 'SHSH Saved!' message once Firmware Umbrella has completed the process.

Step 11: You may now find a new .shsh file created in the Firmware Umbrella folder on the desktop. Save the file for future use.

This completes the process of backing up your ECID SHSH on a Windows computer. Do try the process out and let us know how it works in the comments below. 

[via iClarified]