3.2.1.1 IMAP4 NTLM Extension State Model

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The following figure shows the server IMAP4 NTLM extension state model.

Server IMAP4 NTLM state model

Figure 2: Server IMAP4 NTLM state model

The abstract data model for the IMAP4 NTLM extension has the following states:

  1. Start: State of the server before the IMAP4_AUTHENTICATE_NTLM_Initiation_Command message has been received.

  2. received_authentication_request: State of the server after the IMAP4_AUTHENTICATE_NTLM_Initiation_Command message has been received.

  3. inside_authentication: State entered by a server after it has sent an IMAP4_AUTHENTICATE_NTLM_Supported_Response message. In this state, the server initializes the NTLM subsystem and performs the following steps:

    • Waits for a message from the client.

    • De-encapsulates the received IMAP4_AUTHENTICATE_NTLM_Blob_Command message from the client and obtains the embedded NTLM message data.

    • Passes the NTLM message data to the NTLM subsystem.

    • Encapsulates the NTLM message returned by the NTLM subsystem into an IMAP4_AUTHENTICATE_NTLM_Blob_Response message.

    • Sends the IMAP4_AUTHENTICATE_NTLM_Blob_Response message to the client.

      This state terminates when one of the following occurs:

    • The NTLM subsystem reports completion with either a success or failed authentication status, upon which the server sends the client an IMAP4_AUTHENTICATE_NTLM_Succeeded_Response message or an IMAP4_AUTHENTICATE_NTLM_Fail_Response message, as specified in [RFC1731].

    • The server receives an IMAP4_AUTHENTICATE_NTLM_Cancellation_Command message.

    • Any failure is reported by the NTLM subsystem, upon which the server sends the client an IMAP4_AUTHENTICATE_NTLM_Fail_Response message.

  4. completed_authentication: State of the server on exiting the inside_authentication or the received_authentication_request state. The rules for exiting the inside_authentication state are defined in section 3.2.5.1.2.2, section 3.2.5.1.2.3, section 3.2.5.1.2.4, and section 3.2.5.1.3. The behavior of IMAP4 in this state is outside the scope of this protocol.