Happy Trails iOS 10: Apple stops signing 10.3.3

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In the 15 days since September 19, Apple has released two patch updates. Today they stopped signing iOS 10.3.3, meaning you may no longer downgrade devices to iOS 10.

“Signing” is a colloquial term. When Apple is signing a particular iOS version, it is monitoring and permitting iOS devices to be upgraded (or downgraded) to that iOS version. During the iOS install process, a cryptographic request is sent to Apple with information about the iOS device and iOS version. The response from Apple must be cryptographically “signed” for the install process to proceed. No signing, no install. No woman, no cry.

When Apple releases a new iOS version, it usually does not immediately stop signing the preceding version. iOS 10.3.3 was signed for 15 days after iOS 11 was released. For a period of about 24 hours, Apple was signing a full FOUR versions for many iOS devices: 10,3.3, 11.0, 11.0.1, and 11.0.2.

So for a period of a few days, you can upgrade to, or even downgrade to, a not-so-new version. The process to do that can be a bit tricky: you need to obtain the correct IPSW file first, and use a special key combination (Option) in iTunes to select the file.

We recommend the site [https;//ipsw.me IPSW.me] to check signing statuses and download individual IPSW files for a particular device and version.

GroundControl users: we automatically take care of this process, simply enable iOS Update Delay to use the previous version for as long as possible.

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Aaron Freimark's picture

Aaron Freimark

Joined: Nov 6, 2010
WWW

Signing again?

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They seem to have turned sigining on again for 10.3.3. Reporting this news is hard.

--
Aaron Freimark, Enterprise iOS founder & GroundControl CEO

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