[guardian-dev] developer sneak peak: CacheWord

[Mark Murphy]

On Wed, Mar 20, 2013 at 2:54 PM, Abel Luck <abel at guardianproject.info> wrote:
> I want to be able to perform zeroization on the cached data fields
> before my process is terminated, which is one benefit to using the Alarm
> Manager like I currently am.

Not really. Your process will be terminated with or without
AlarmManager. All you are doing with AlarmManager is creating
*another* process, if the first one was terminated.

> But it sounds like a ScheduledExecutorService will not give me the
> opportunity to run this wiping code.

Nothing at the SDK level gives you the opportunity to run this wiping
code, if the process terminates before your timeout. Bear in mind that
many things can trigger your process to be terminated, including the
user running a task killer, or even just swiping you off the
recent-tasks list on Android 4.0+.

> I realize there is no POSIX/Linux facility for "run some code before
> your pid is terminated by the kernel" (aside from catching SIGTERM perhaps)

It's conceivable that you could catch SIGTERM in the NDK layer, though
the state of the VM at this point is indeterminate. I haven't tried
that or run into any discussions about that approach.

If you absolutely have to have "zeroization" (which, BTW, is an
awesome nounification of a noun you previously verbified!), you could
see if SIGTERM can be caught at the NDK level, and then maintain your
credentials in native code instead of in the Dalvik VM.

--
Mark Murphy (a Commons Guy)
http://commonsware.com | http://github.com/commonsguy
http://commonsware.com/blog | http://twitter.com/commonsguy

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