Question

I’ve downloaded and compiled Android 2.1 version with signed-google_ion-ota-14721.zip image for my HTC phone. The compile completed successfully and so the system image flash.
How can I sign my own Android application with the system signature?

Can someone describe the whole process for signing a user application with system signature as I am completely new to the signing process.

Answer 1

Finally I managed to discover a way to sign my application with the platform signature. You need to use keys located in <root-of-android-source-tree>/build/target/product/security/ and add android:sharedUserId="android.uid.system" in your AndroidManifest.xml file.

Details from this google groups thread:

On top of signing Android 1.6 for Dream with certificates generated by
myself, I’ve also managed to sign my app with the platform certificate
and run it with the system sharedUserId. These are the steps I took:

• Build and flash to your Dream your own Android using https://web.archive.org/web/20081211205758/http://source.android.com:80/documentation/building-for-dream. Use the
  mkkey.sh script on
  https://web.archive.org/web/20091213215940/http://pdk.android.com/online-pdk/guide/release_keys.html to create
  new certificates, including x509 certificates before you do ‘make’.
• In the AndroidManifest.xml of your application: under the <manifest> element, add the attribute android:sharedUserId="android.uid.system".
• Export an unsigned version of your Android application using Eclipse: right-click on the project >> Android Tools >> Export
  Unsigned Application Package.

• Use <root-of-android-source-tree>/out/host/<your-host>/framework/signapk.jar to sign your app using platform.x509.pem and platform.pk8 in <root-of-android-source-tree>/build/target/product/security
  generated earlier:

  java -jar signapk.jar platform.x509.pem platform.pk8 YourApp-unsigned.apk YourApp-signed.apk.
  

• Install the app to your device:

  adb install YourApp-signed.apk
  

• Run your app
• Use adb shell ps to confirm that your app is running as system.