Future-proofing the 3GS jailbreak If theres one thing weve been stressing the last few weeks, its that if you want to keep the jailbreak or unlock on your 3GS, you should resist all urges to install Apples official firmware updates without knowing if a jailbreak exists for that version yet. Unless another (different) bootrom exploit is found for the 3GS that doesnt require a foot in the door with a signed official iBoot, then accepting official updates willy-nilly may cause you to be cutoff from the jailbreak. And it will definitely cause you to be cutoff from the carrier unlock.
Now, there are ways to ensure that even after taking an official 3GS update (which you really shouldnt do!), that youll nonetheless be able to revert to a jailbreakable 3GS (this is NOT true for the unlock, see NOTE #1 below). Weve been explaining these methods (like the iTunes /tmp technique) over the last few weeks, and theres been some great discussion and feedback for the methods in the comments.
Having said all that, we realize that some of you updated your 3GS to 3.1 anyway. If you want to come back to the world of the jailbreak (but NOT the sim unlock, sorry!) then sauriks new on file server may be able to help. Hes got all the details in a new article so do check it out.
Even if you did not update your 3GS to official 3.1 (good job! You really shouldnt do that!), then you should still read the article and make those changes today. We fully recommend redirecting your iTunes signing process through sauriks on file server to future-proof your 3GS jailbreak through all future updates.
AFTER ADJUSTING YOUR ITUNES SETUP, YOU SHOULD STILL AVOID DOING AN ACTUAL FIRMWARE UPDATE. For all the reasons mentioned in this post, youll lose the unlock forever, and lose the jailbreak until a new one for 3.1 comes out. And theres no guarantee that your 3.0 signed files were captured by saurik in time. This is more about protecting your 3GS jailbreak in future updates its not a way to jailbreak 3.1 right now.
NOTE #1: the carrier sim unlock is a different story. Jailbreaking and unlocking have two different security mechanisms, and if you update your 3GS (or 3G) to 3.1, you will lose your carrier unlock, possibly forever. Even if you downgrade from 3.1 to 3.0, you will have lost your carrier unlock. So if you think youll ever want to carrier unlock your 3G or 3GS (or maybe give it away or resell it later as an unlockable iPhone), then please stay clear of all official Apple IPSWs. Youll soon be able to create custom 3.1 IPSWs using PwnageTool that let you pre-hack your 3.1 update in a way that preserves the carrier unlock.
NOTE #2: The custom IPSW flow using PwnageTool also ensures that even if Apple fixes all the iBoot holes, youll still be able to retain your jailbreak through later updates. Thats because a jailbroken iPhone will happily accept a custom (pre-jailbroken) firmware update even though its not blessed with Apples signatures. This is the once jailbroken, always jailbroken approach. Its very powerful, but it requires you to only update to pre-hacked IPSWs.
NOTE #3: None of this applies if you have an iPhone 2G, iPod touch 1G, or iPod touch 2G. The iPhone 3G is also unaffected by Apples signing process for the jailbreak, but it is susceptible to permanent loss of the carrier unlock as mentioned in note #1.
Gast
