title: Best practice for storing and protecting private API keys in applications
body: <p>Most app developers will integrate some third party libraries into their apps. If it's to access a service, such as Dropbox or YouTube, or for logging crashes. The number of third party libraries and services is staggering. Most of those libraries and services are integrated by somehow authenticating with the service, most of the time, this happens through an API key. For security purposes, services usually generate a public and private, often also referred to as secret, key. Unfortunately, in order to connect to the services, this private key must be used to authenticate and hence, probably be part of the application. 
  Needless to say, that this faces in immense security problem. Public and private API keys can be extracted from APKs in a matter of minutes and can easily be automated. </p>
  
  <p>Assuming I have something similar to this, how can I protect the secret key:</p>
  
  <pre><code>public class DropboxService  {
  
      private final static String APP_KEY = "jk433g34hg3";
      private final static String APP_SECRET = "987dwdqwdqw90";
      private final static AccessType ACCESS_TYPE = AccessType.DROPBOX;
  
      // SOME MORE CODE HERE
  
  }
  </code></pre>
  
  <p>What is in your opinion the best and most secure way to store the private key? Obfuscation, encryption, what do you think?</p>