Q:

How do you sign an app with a debug key that has system (signature) permissions

All I want to do is shut my screen off in my app and I've added these lines to my manifest file:
<uses-permission android:name="android.permission.DEVICE_POWER" 
    android:protectionLevel="signature" />

Yet when I run my app I get a SecurityException on DEVICE_POWER. So I looked into it and apparently I need to sign my app with a key in order to have signature permission.
Well I tried to export a signed app using the Android Tools in eclipse and then running that exported apk on my phone but it still doesn't work. 
How do I sign a system signature key to debug with in eclipse? As well export it properly to work when I'm finished?
Can anyone please help me out. All I want my app to do is shut the screen off and this is becoming a big roadblock for me!

A:

System keys could only be provided by Google or the Manufacturers. You cannot sign a user created app using a system signature. That would be a huge security risk. This applies for non rooted androids. 
For rooted phones there are custom firmwares and different techniques to make the phone treat your app like a system app.

