07-15-2010, 11:36 PM
john-o wrote:
Thanks Gilbert, but I'm still not clear about what the SHSH has to do with doing a JB...
Nothing with jailbreaking. Storing your SHSH lets you reinstall the iOS that is currently on your iOS device later. The SHSH is basically a signature file of your device with that specific iOS. When you try to reinstall iOS, if it isn't the most current version of iOS, iTunes checks to see if that SHSH is on file. If that SHSH is on file, then itunes allows the install. If that SHSH isn't on file, then the install isn't permitted. Tiny umbrella stores the SHSH on cydia. If you select the advanced option then you can store the SHSH on Apple's server. 'Apples server' is really your machine but TU makes it look like the apple server.
A perfect example is my old 3gs iphone. I had my SHSH for 3.1.2 stored on cydia. Jailbreaking iOS4 required a JB iOS3 first. I already had iOS4 installed. Since I had my SHSH for 3.1.2 stored on cydia, I was able to downgrade from iOS4 to 3.1.2, jailbreak 3.1.2, and then install a modified version of iOS4.
So it is recommended to store your SHSH for your iPod/iPhone/iPad even if you never intend on JB the device. If you ever need to downgrade the iOS, this will let you do that.