EAP-TTLS

和EAP-TLS

 EAP-TTLS is an EAP (Extensible Authentication Protocol) method that
   encapsulates a TLS (Transport Layer Security) session, consisting of
   a handshake phase and a data phase.  During the handshake phase, the
   server is authenticated to the client (or client and server are
   mutually authenticated) using standard TLS procedures, and keying
   material is generated in order to create a cryptographically secure
   tunnel for information exchange in the subsequent data phase.  During
   the data phase, the client is authenticated to the server (or client
   and server are mutually authenticated) using an arbitrary
   authentication mechanism encapsulated within the secure tunnel.  The
   encapsulated authentication mechanism may itself be EAP, or it may be
   another authentication protocol such as PAP, CHAP, MS-CHAP, or MS-
   CHAP-V2.  Thus, EAP-TTLS allows legacy password-based authentication
   protocols to be used against existing authentication databases, while
   protecting the security of these legacy protocols against
   eavesdropping, man-in-the-middle, and other attacks.  The data phase
   may also be used for additional, arbitrary data exchange.