OTA Updates

OTA (over the air) updates were introduced with iOS 5. They allow a user to update the firmware on their device without the desktop iTunes program.

Contents

There are three known versions of the update file containers.

Version 1

Version 1 updates came first, and were replaced with version 2 with iOS ???. They contain three main files:

  • archive.cpio.gz: The actual encrypted patch archive. It is a collection of BSDIFF40 and the requisite flashing tools (bbupdater, imeisv, etc.).
  • Info.plist and Info.plist.signature: Contains information about the update along with a signature.
  • libupdate_brain.dylib: A code library for stage 2 of the update process.

Version 2

Version 2 updates were introduced with iOS ???. Instead of an archive.cpio.gz file, they contain two folders: added and patches. As their names imply, added contains unencrypted files to be added to the filesystem while patches contains BSDIFF40 files of files that need to be patched.

Version 3

Version 3 updates were introduced with iOS ???. Quite a number of changes were made to the structure. The most major changes are listed below:

Version 3 update files were introduced with iOS ???. Quite a number of changes were made to the folder structure. The most major changes are listed below:

  • The added folder no longer exists.
  • links.txt was added. It contains a list of symbolic links (symlinks) to be created.
  • The patches folder contents no longer use the BSDIFF40 file format, but a modified version known as BXDIFF41.
  • payload and prepare_payload were added. They hold the filesystem contents in a proprietary format.
  • removed.txt was added. It contains a list of files to be deleted prior to updating.

List of OTA Updates

This is a comprehensive list of every OTA update that has been released to the public.

AirPods

Apple TV

Apple TV Accessories

Apple Watch

HomePod

iPad

...

iPad Air

...

iPad mini

...

iPad Accessories

...

iPhone

...

iPod touch

...