126.96.36.199 Negotiate Authentication Protocol
This use case describes how a client and a server application can negotiate to select an agreed-on common authentication protocol.
Figure 25: Negotiate authentication protocol
Context of Use: A client application has to access a service on a network that requires verification of client identities, and the client and server applications are coded to use SPNEGO to negotiate a common authentication protocol.
Direct Actor: The client application or the server application, depending on how negotiation starts.
Primary Actor: The user.
The user that started the client application is logged on to the client computer.
The client application, server application, and AA can communicate with each other.
The client and server application are configured to negotiate an authentication protocol.
Minimal Guarantees: Negotiation fails in some scenarios when a non-Windows system participates and there is no common protocol, or when the client or server application receives another reason for failure.
Success Guarantee: Both the client and the server agree on a common authentication protocol.
Trigger: The client application has to access a protected resource or a service on the server computer and: a) The client starts the negotiation phase before a request; or b) The server starts the negotiation phase in reaction to a request; or c) The server rejects access, and the client initiates the negotiation phase. The trigger depends on the implementation of the application protocol.
Main Success Scenario: The server starts the negotiation phase in reaction to a request.
The server application sends the preferred authentication protocol and a list of available authentication protocols in priority order to the client application.
The client application sends the preferred authentication protocol and a list of available authentication protocols in priority order to the server application.
The server application agrees on a common protocol and returns the state of negotiation to the client application.
Postcondition: Both the client and server application have agreed on a common authentication protocol for further authentication process.