iFaith is a new program for Windows made by iH8sn0w that brings an extremely important functionality for iDevices owners. You know that any iPhone 3GS/4, iPod Touch 3G/4G or iPad/iPad 2 tablet needs SHSH to restore to any version of iOS. If you don't have SHSH for a certain version of iOS, you can't restore in any way, so basically you are obliged to install only versions of iOS for which you have SHSH or the newest version of iOS from iTunes.
iFaith solves this problem because it gives us the possibility to save SHSH for any version of iOS installed in our terminal. No matter what version of iOS higher than 3.x you have in the terminal, you will be able to save SHSH using iFaith. The SHSHs are saved on your computer but also on a server, probably iH8sn0w's. Using these SHSHs for restore is more complicated than normal because we are talking about a different kind of process.
Basically, iFaith allows saving the SHSH for the iOS version from our terminal, but it also allows building a custom ipsw with that SHSH. We will be able to use the SHSH saved ONLY through the custom ipsw made with iFaith. iFaith has a special process that implements SHSH in custom ipsw and allows us to use it for restore without any worries.
SHSHs cannot be saved in Cydia, they are saved only on a certain server, iH8sn0w's probably.
This is what I have understood so far from iH8sn0w's presentation, I will complete the article as new information appears.
The difference between iFaith and TinyUmbrella is that iFaith can save SHSH for ANY version of iOS that is installed in your terminal, but TinyUmbrella saves SHSH ONLY for the current version of iOS. Ex: If you have iOS 4.1 on your terminal you can save SHSH with iFaith for iOS 4.1 but with TinyUmbrella you can't because iOS 4.3.3 is the current version of iOS and TinyUmbrella can only save SHSH for 4.3.3.
You can download iFaith from here.
UPDATED: Tutorial that will teach you how to use iFaith you can find here.
