Full Disclosure mailing list archives
Decrypting encrypted iPhone backups
From: "Adam Behnke" <adam () infosecinstitute com>
Date: Tue, 29 May 2012 19:44:38 -0500
Data protection mechanism introduced in iOS 4 protects the sensitive data in files on the file system and items in the keychain by adding another layer of encryption. Data protection uses the users passcode key and the device specific hardware encryption keys to generate a set of class keys which protect the designated data. Developers use the data protection API to add protection class flag to the files and the keychain items. On the iPhone, protection class keys are stored in the System Keybag. During the backup, iTunes generates a new set of protection class keys and stores them in the Backup Keybag. Class keys stored in the System Keybag are different from the keys in the Backup Keybag. Protected files and data in the backup are encrypted using the class keys that are stored in the Backup Keybag. In normal backups Backup Keybag is protected with a key generated from the iPhone hardware (Key 0×835) and in encrypted backups it is protected with the iTunes password. The article at InfoSec Institute here: http://resources.infosecinstitute.com/iphone-forensics-part2/ discloses the procedure to extract protection class keys from the Backup Keybag and covers the techniques & the tools to decrypt the protected backup files and the encrypted backups. _______________________________________________ Full-Disclosure - We believe in it. Charter: http://lists.grok.org.uk/full-disclosure-charter.html Hosted and sponsored by Secunia - http://secunia.com/
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- Decrypting encrypted iPhone backups Adam Behnke (May 29)