Downgrading new iPhone 4?

[Synomenon]

A friend just got a new iPhone 4, but it has iOS 4.3.5. Is there any way to downgrade it to 4.3.3? I have a backup copy of 4.3.3 on my PC.

 

[eelw]

Most likely not. If it was a refurb, and the prior owner had jailbroken it and saved the SHSH blobs to cydia, then yes. But brand new from Apple, you're stuck with current firmware.

 

[amdhunter]

Not without saved SHSH blobs, which he doesn't have because it's new. 🙁

 

[Synomenon]

So these SHSH blobs are unique to every device? Like a serial number?

 

[ViRGE]

So these SHSH blobs are unique to every device? Like a serial number?

Correct. It's a 128B public key signature composed of the firmware image and the device's unique ID (UDID). It's completely unique to each device and impossible to reverse/create as only Apple has the private key. Every firmware/device combination results in a new SHSH signature.

 

[Synomenon]

Does it change with each firmware update?

 

[gevorg]

just wait until next month when iOS 5 comes out, there is a jailbreak cooking by DevTeam

 

[Emulex]

yah but ios5 has OTA updates and you know how the last upgrade went SLOOOOOOW. The new devices will have 1gb of ram, you should tread lightly before doing a damn new irreversible upgrade.

 

[ViRGE]

Does it change with each firmware update?

Yes, which is why you have to store the old SHSH blobs to reuse them.

 

[gevorg]

yah but ios5 has OTA updates and you know how the last upgrade went SLOOOOOOW. The new devices will have 1gb of ram, you should tread lightly before doing a damn new irreversible upgrade.

It might be slow for 3GS, but the 4 should handle iOS 5 just fine. And the OTA updates are not enforced (I hope), so you should be able to disable updating until a proper jailbreak is released.

 

[ViRGE]

It might be slow for 3GS, but the 4 should handle iOS 5 just fine. And the OTA updates are not enforced (I hope), so you should be able to disable updating until a proper jailbreak is released.

It's better than that: if Apple detects a jailbroken phone, they won't even push OTA updates to you. Apple wants to update jailbroken phones even less than the people who jailbroke them - there's no way to tell how a delta update would interact with the jailbroken OS, and Apple doesn't want to deal with the support issues that might result.