title: Content Provider Protection Level using Signature
body: <p>To protect malicious applications from accessing a content provider, 1 way is to set the  android:protectionLevel=&quot;signature&quot;.</p>
  <p>This way, only another app that has been signed with the same signature could access the contents of a content provider.</p>
  <p>But is it safe? How does it check the signature? For example I have a signed App A, is the signature stored somewhere for another app to check?</p>
  <p>Or the checking is done by another mechanism?</p>