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[help] Downgrade Iphone 3G from 4.1 to 2.0


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#1
shinzou.

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As the title says, can I downgrade my Iphone 3G from the firmware 4.1 to the early 2.0 ? I want to check the speed of the first iOS. Thanks to all

#2
shinzou.

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Help?!

#3
kompile15

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It *may* be possible, but I seriously doubt it, and here is why:

As of now, Apple "signs" all new firmware bundles that they release. What this means is that every time you try to restore your phone, iTunes sends a request to the Apple servers with the firmware bundle version that you are attempting to use. If the servers see that you are trying to use an old firmware bundle, they deny your request and iTunes reports back that you can't restore with the selected firmware. "So can't I block iTunes' connection with Little Snitch or turn off my access to the internet?" you ask. Unfortunately no. If iTunes doesn't have access to its servers, you just can't restore. So basically, Apple forces you to use the most current iOS.

There is a way around this, but in your case I am nearly positive you can't do this. There is a program called Tiny Umbrella, and what this does is save your "SHSH blobs" to your computer, and also to Cydia's server. These are what the "requests" that iTunes sends to the servers are looking for. Basically (if I understand it correctly), when you want to restore you point iTunes to check with your machine or Cydia (instead of Apple), and if you have old SHSH blobs saved, iTunes will allow the restore process to proceed.

Here's the problem: you have to save the SHSH blobs before a new version of the firmware is released. Once a new version is released, you can only save the blobs for the current version. So, I have an iPhone 3G with SHSH blobs 4.0, 4.0.1, 4.0.2, 4.1, but my iPhone 4 only has SHSH for 4.2b3 and 4.2.1 because I just got it last week. There is no way for me to downgrade my iPhone 4 to anything lower than 4.2b3. Oh, and there is no way to get these blobs from another 3G user because these blobs are unique to each phone.

Finally, do you jailbreak/unlock your phone, or is it a non-modded phone? If you jailbreak or unlock I highly suggest that you download Tiny Umbrella and start saving your SHSH. If you don't need to jailbreak, then I don't think it matters, you just won't be able to downgrade to anything, only restore to the current version.

Sorry for the super long post...maybe you didn't want to read that much.

Jon

#4
shinzou.

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Thank you very much Jon, useful post.





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