Apple Cydia's TSS Server Discussion

[Latiken]

If you notice today on Cydia at the top where it would usually say "SHSH: iOS (insert iOS v here)" it now says something like "head to Cydia TSS server area." When you go there it has an article from Jay Freeman, the man behind Cydia. Basically, it appears is if SHSH blobs are useless now. They now talk about TSS info or something and its only affective on limera1n exploited devices.

My Cydia now says I have no SHSH even though I had iOS 6.1, 6.1.2.
What is going on?

Cropped.

 

[Lacius]

SHSH blobs are only useless on anything newer than A4 devices. SHSH blobs can still be used on A4 or older devices to restore/upgrade/downgrade without the need for verification by Apple.

Your problem with missing 6.1 and 6.1.2 SHSH blobs is a different story. The way they were stored in Cydia was messed up, so they're useless for most people. The problem has been resolved, so any future SHSH blobs you backup (6.1.3, for example) will be useful in the future. If you backed up your 6.1.2 SHSH blobs using a program on your computer (like TinyUmbrella), they will still work. If you only relied on Cydia to back them up for you, those are useless.

 

[Latiken]

Well thank God and all that is good that I saved my blobs on my computer, my flash drive, and both my emails!
Keep discussing! What is this "TSS server?

 

[Lacius]

The TSS Center is how you manually go about backing up SHSH blobs using Cydia. For example, you can backup your 6.1.3 blobs through Cydia by clicking "Save 6.1.3 Now." Alternatively, you can also use a program like redsn0w to upload your locally backed up SHSH blobs to Cydia's servers.

 

[Izen]

The TSS (stands for Tatsu Signing Server, but is always referred to as the redundant "TSS server" as opposed to just "TSS.") server is what iTunes talks to in order to get a confirmation that it's okay to update or restore a device. You click Restore in iTunes, iTunes asks the TSS server if it's okay to restore to this iOS version, the TSS server responds back to iTunes, the iTunes will either begin your restore if the TSS server allows it, or throw you an error code if it doesn't.

Cydia includes a service emulates Apple's TSS server. In order to do so, it needs some things before-hand that it grabbed from Apple's TSS server at the appropriate time. For iOS 3 and 4, all it needs is the SHSH, which is basically a thumbs up from the TSS server. There's no issue there. However, iOS 5 introduced something new.

In iOS 5, the old SHSH method of verifying restores was all but thrown out for the new, more complicated APTicket method. APTickets need more information to be useful than SHSHs, and iOS 6 APTickets need even more. Cydia, partially due to Saurik's unfamiliarity with the APTicket, did not grab all that required information for the iOS 6 APTickets, so the APTickets it backed up are essentially useless.

It's really not much of an issue for anyone. If your device is not vulnerable to the limera1n exploit, there was absolutely nothing you could do with the iOS 6 APTickets, even if they were backed up correctly. There are no exploits for these devices that allow them to be restored to a firmware Apple is signing besides MuscleNerd's re-restore for iOS 5 and the iPad 2's restorability with iOS 4 SHSHs backed up (neither of these methods use iOS 6 APTickets in any way). For older devices that are vulnerable to the limera1n exploit, you can use iFaith or redsn0w (you'll have to wait for the next version of redsn0w, though) to get all the missing TSS information from your device and upload it to Cydia, thus completing the backed up APTickets and making them usable.

So no harm no foul, unless some dev out there finds an exploit that allows restoring the iOS 6 using APTickets, but even then, he would probably just hold the exploits until iOS 7.