title: Using Google oAuth between applications which the same user is authenticated into?
body: <p>I have run into some challenges when using oAuth, and I would appriciate some expert advice!</p>
  
  <p>The challenge is as follows:</p>
  
  <p><strong>Scenario</strong><br>
  <strong>1.</strong> User A uses two seperate &amp; external web applications (App X &amp; App Y) synchronously.<br>
  <strong>2.</strong> User A authenticates into App X &amp; App Y by using the same Google authentication credentials (OpenID / oAuth).<br>
  <strong>3.</strong> App X &amp; App Y currently hold authorized Google auth tokens for User A.<br>
  <strong>4.</strong> App X &amp; App Y need to share information between themselves (via REST/SOAP requests), in order to fulfill User A's requirement.<br>
  <strong>5.</strong> App X &amp; App Y have a security requirement needing any external App to authenticate before accepting a REST/SOAP request.<br></p>
  
  <p><strong>Question</strong><br>
  Can App X &amp; App Y utilise User A's Google credentials (token) which they hold to mutally authenticate prior to generating/sending REST/SOAP requests to each other?</p>
  
  <p>If there is a better way, I would appriciate your thoughts.</p>
  
  <p>Thank you in advance.</p>