First of all, I do not know if everybody is familiar with the term of SHSH blobs and I want to make things clear before I continue. SHSH blobs represent signatures HaSH, namely a random string of numbers and letters, through which Apple verifies if your device has been downgraded to a previous version of iOS. Once you upgrade to a different iOS, you are not able to downgrade it because these signatures do not allow you to. For example, if you want to downgrade from 5.1 to 5.0.1, you need to have 5.0.1 SHSH saved on your device. This thing is possible by using the TinyUmbrella application.
The TinyUmbrella gives you the possibility to save SHSH for iOS 5.1.1, which has be currently updated. Therefore, if you want to be able to downgrade your iOS and to be able to perform jailbreak on further iOS released, you need to back up your SHSH blobs. Here are the steps you need to perform if you are planning to use this application to save your SHSH blobs for your current iOS firmware. In fact, it is a simple how to guide and it will take only several minutes.
Step 1: The first thing you have to do is to download TinyUmbrella to your computer. It is free for download and you can find it easily.
Step 2: Proceed with the process of installation and at the end of it, launch the application.
Step 3: The next step requires plugging your device to your computer in order for the software to recognize it. TinyUmbrella will detect your device in the list of connected devices.
Step 4: Once you select your device, you need to click on the Save SHSH button that is placed in the right corner of the window. At this point, the application will start to save your SHSH blobs. When this is completed, you will be able to see a list of Saved SHSH blobs, which will be available for using them later.
This is all. You have now saved the SHSH blobs running on your current iOS firmware. Remember that each time you upgrade your device and you intend to keep the respective version, you need to redo this whole process all over again just to be covered for the time you decide to downgrade once again.