SharePoint 2013 includes improvements to claims-based authentication that enable new server-to-
server and app authentication scenarios. Key changes include easier migration to claims-based
authentication, caching of login tokens in the Distributed Cache Service, improved logging for
troubleshooting authentication issues, and extensions to OAuth to support server-to-server
authentication between SharePoint and other services like Exchange and Lync.
See Also
App authentication
SharePoint 2013 also extends OAuth to implement an app authentication protocol that enables apps to
authenticate and request access to SharePoint resources on behalf of a signed-in user. SharePoint 2013
includes a dedicated app security token service (STS) that issues app identity tokens to apps.