title: Detecting code tampering in Apk
body: <p>I am particularly new to App development and have learnt lately about the entire Signing process of an apk, why it's mandatory and it's importance to prevent unauthorized and tampering of the app.
  One of the famous checks for Signature refers to using the PackageManager class to do signature verification. Is there any other method which checks for the META-INF directory in the apk itself for tampering or other abusive activities to verify the App is not tampered and intact with its original signature?</p>