title: Questions about Development and Release Key Hashes for Facebook SDK for Android
body: <p>I read the guides in the FB Developer website.</p>
  
  <h2>To create a Development Key Hashes</h2>
  
  <pre><code>keytool -exportcert -alias androiddebugkey -keystore ~/.android/debug.keystore | openssl sha1 -binary | openssl base64
  </code></pre>
  
  <h2>And to create a Release Key Hashes</h2>
  
  <pre><code>keytool -exportcert -alias YOUR_RELEASE_KEY_ALIAS -keystore YOUR_RELEASE_KEY_PATH | openssl sha1 -binary | openssl base64
  </code></pre>
  
  <h2>I have 6 questions:</h2>
  
  <ol>
  <li><p>What do those Key Hashes do?</p></li>
  <li><p>Why is there a need to create different key hashes for both <code>Release</code> and <code>Development</code>?  </p></li>
  <li><p><strong>If I haven't</strong> published my app to the PlayStore yet. Can I use the <code>Release Key</code> instead of using the <code>Development key</code>?</p></li>
  <li><p><strong>If I my app is live</strong> in PlayStore, can I keep using the <code>Development</code> key?</p></li>
  <li><p>What should I put into <code>YOUR_RELEASE_KEY_ALIAS</code> and <code>YOUR_RELEASE_KEY_PATH</code>? Can anyone provide samples please?</p></li>
  <li><p>Why is that when we develop for iOS, those key hashes were not required?</p></li>
  </ol>
  
  <h2>Extra question that is unrelated</h2>
  
  <p>What does this <strong>Single Sign On</strong> button do?
  <a href="https://i.stack.imgur.com/OdAIA.png" rel="noreferrer"><img src="https://i.stack.imgur.com/OdAIA.png" alt="enter image description here"></a></p>