And also what kind of key this is. For example, if there is a per-device
public key, it would be nice from an enterprise POV to be able to use this
same feature for enterprise/side-loaded apps.

On Mon, Jul 16, 2012 at 11:08 AM, Dru <[email protected]> wrote:

> Thanks for the extra info Nikolay. Has anyone found where the key is
> stored as that seems pivotal to the entire security. Also, it seems the
> protection will fall apart on a rooted device where the package can be
> easily repackaged without the encryption and then redistributed.
>
> On Sunday, July 15, 2012 7:30:17 AM UTC-7, Nikolay Elenkov wrote:
>
>> On Fri, Jul 6, 2012 at 7:24 PM, Kevin Chadwick wrote:
>> >> > on the device. The actual APK saved on disk is not encrypted, so it
>> works
>> >> > just
>> >> > as before and no keys are saved on the device. This certainly does
>> >> > not stop anyone with a rooted devices from pulling the APK from the
>> device.
>> >
>>
>> Now that JB source is out, it turns out there is one more piece to the
>> puzzle
>> -- forward locking. If the 'forward lock' flag is set, an encrypted
>> EXT4 container will be built for the app, and the app itself will be
>> split into a
>> public part (resource) readable by everyone and a private part (the
>> actual APK),
>> readable only by root. The whole thing is loopback mounted under
>> /mnt/asec/package.name, just as it was done for apps moved to the SD
>> card.
>> So paid apps (or apps you installed via adb with the -l option) are
>> indeed
>> encrypted with a device-specific key when stored on the device. Which
>> makes
>> it slightly harder to pull the apk and will probably confuse some backup
>> apps.
>> adb backup seems to filter out forward-locked apks, so you only get the
>> preferences and data files in the backup.
>>
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