Every time Apple releases a new version of iOS hackers start looking for ways to jailbreak it — but usually not without issuing warnings. If you rely on a carrier unlocking utility, for instance, you typically need to wait a while before you can upgrade to a new version of the iPhone operating system or you may lose the ability to make calls on your preferred network.
So what happens if you fail to heed that warning and update your iPhone software anyway? Or what happens if your iDevice doesn’t run as well after updating the software? Can you go back to a previous version? Sometimes.
It’s a lot easier to upgrade from one version of iOS to the next than it is to downgrade. But ih8sn0w, the developer behind the sn0wbreeze tool for jailbreaking and customizing iDevices has released a new tool called iFaith which makes the process a little easier and more reliable.
Basically you can’t just download older iPhone software from the web and flash it onto your device, because when Apple checks to see what version of iOS you’re trying to install it looks for a unique identifier for your device. What Apple looks for is something called an SHSH blob. If you’re getting ready to upgrade to a new version of iOS but want to be able to downgrade afterward if anything goes wrong, you’ll want to save your SHSH Blob, which will allow you to trick Apple into thinking you’re already running an older version of iOS when you want to restore your system using an older OS.
There are already tools such as TinyUmbrella which allow you to do this. But once Apple stops signing a version of iOS (which the company usually does after pushing out a new version), those tools don’t let you get SHSH blobs, so you had to backup your blobs quickly.
With iFaith, there’s no rush. It allows you to dump SHSH blobs and save them even after Apple stops signing the firmware. In addition to allowing you to save blobs locally, iFaith stores copies on a remote server.
You can also use iFaith to build custom .ipsw restore files using your backed up SHSH blobs or browse available blobs on the server.
The app is available as a free download from ih8sn0w. It should work with every device that currently supports the limera1n jailbreak, which includes the iPhone 3GS and iPhone 4, iPod touch 3rd and 4th generation, original iPad and Apple TV 2. The iPad 2 isn’t currently supported.
via FSM, iPhone Download Blog, and Redmond Pie