Add your development and release key hashes To ensure the authenticity of the interactions between your app and Facebook, you need to supply us with the Android key hash for your development environment. If your app has already been published, you should add your release key hash too. You'll have a unique development key hash for each Android development environment. To generate a development key hash, on Mac, run the following command:
keytool -exportcert -alias androiddebugkey -keystore ~/.android/debug.keystore | openssl sha1 -binary | openssl base64
On Windows, run this command: