Difference between revisions of "IM4P File Format"

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m (External Links: Gr, stop doing that)
m (No IM4P for iPhone 5c (it still uses IMG3s))
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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]].
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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 5s]] and newer, [[iPad Air]] and [[iPad mini 2G]].
   
 
The file is encoded as an DER encoded asn.1 object, structured like this:
 
The file is encoded as an DER encoded asn.1 object, structured like this:

Revision as of 21:36, 15 September 2014

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 5s 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

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