title: OpenID Connect - should the id token be sent to the protected resource in this case?
body: <p>Lets say I have a web API that a native application needs to make requests to. This API needs to authenticate who the user is that's making these requests via the native app. OpenID Connect seems to be the right choice since it is about authentication rather than authorization with OAuth. </p>
  
  <p>The native app sends the users credentials to the IDP and gets back an access token (for authorization) and an id token (for authentication). From what I understand of OIDC, the access token would be sent to the API but the id token is only for the native client app. That doesn't make sense to me because it's the API that cares about who the user is, not the native app. </p>
  
  <p>So why isn't the id token also passed to the protected resource (aka the API)? If you don't pass the id token to the API, what guarantees that the access token is secure and can be used to authenticate the user? Otherwise it would seem to lose the benefit of using OIDC over OAuth.</p>