On Wed, Jul 4, 2012 at 2:44 PM, Nikolay Elenkov
<[email protected]> wrote:
> Apparently this never made it to the list, forwarding.
>
> ---------- Forwarded message ----------
>
> On Thu, Jun 28, 2012 at 3:15 PM, Nikolay Elenkov
> <[email protected]> wrote:

>
> It seems that this is actually baked into the PackageManagerService
> and the DefaultContainerService and APKs are decrypted on the fly
> as needed. You can install encrypted APKs using adb install
> (which just calls pm install), but you need to specify the key/IV, so
> the app is decrypted before being installed.
>
...
>
> This still leaves the question where the encryption key is stored
> (most probably in the keystore) and who generates it (Play Store
> based on device+user ID, or the device itself).

And looking into this a bit more, it looks like the Market/Play is sending
you an encrypted APK, along with the encryption parameters (probably not
in the same message, but haven't looked in detail). So it's actually decrypted
and/or verified (by PackageManagerService and friends) before being installed
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.

Maybe this will change in the future, but not sure what the merit is
in the current form (aside from making it harder to intercept an APK
download and use it on some other device).

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