IM4P File Format

From The iPhone Wiki
Revision as of 09:47, 15 September 2014 by Danzatt (talk | contribs)
Jump to: navigation, search

The IM4P file format is a replacement of the IMG3 File Format used on older devices. It was introduced with iOS 7.0.1 and appears to be exclusive to the iPhone 5c and newer, iPad Air and iPad mini 2G.

The file is encoded as an DER encoded asn.1 object, structured like this:

sequence [
   0: string "IM4P"
   1: string type   - ibot, rdsk, sepi, ...
   2: string description   - 'iBoot-1940.1.75'
   3: octetstring    - the encrypted data
   4: octetstring   - containing asn1 encoded KBAG values
        sequence [
           sequence [
               0: int: 01
               1: octetstring: iv
               2: octetstring: key
           ]
           sequence [
               0: int: 02
               1: octetstring: iv
               2: octetstring: key
           ]
        ]
]

each .im4p file is accompanied with a .plist file containing the sha1 of the .im4p file.

External Links

Apple-logo.png This article is a "stub", an incomplete page. Please add more content to this article and remove this tag.