rfc1508.txt

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         remaining lifetime, suitable usage modes, and supported
         mechanism types.



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RFC 1508               Generic Security Interface         September 1993


      o  GSS_NO_CRED indicates that no information could be returned
         about the referenced credentials, either because the input
         cred_handle was invalid or because the caller lacks
         authorization to access the referenced credentials.

      o  GSS_FAILURE indicates that the release operation failed for
         reasons unspecified at the GSS-API level.

   The GSS_Inquire_cred()  call is defined primarily for the use of
   those callers which make use of default credentials rather than
   acquiring credentials explicitly with GSS_Acquire_cred().  It enables
   callers to determine a credential structure's associated principal
   name, remaining validity period, usability for security context
   initiation and/or acceptance, and supported mechanisms.

2.2.  Context-level calls

   This group of calls is devoted to the establishment and management of
   security contexts between peers. A context's initiator calls
   GSS_Init_sec_context(),  resulting in generation of a token which the
   caller passes to the target. At the target, that token is passed to
   GSS_Accept_sec_context().  Depending on the underlying mech_type and
   specified options, additional token exchanges may be performed in the
   course of context establishment; such exchanges are accommodated by
   GSS_CONTINUE_NEEDED status returns from GSS_Init_sec_context()  and
   GSS_Accept_sec_context().  Either party to an established context may
   invoke GSS_Delete_sec_context()  to flush context information when a
   context is no longer required. GSS_Process_context_token()  is used
   to process received tokens carrying context-level control
   information. GSS_Context_time()  allows a caller to determine the
   length of time for which an established context will remain valid.

2.2.1.  GSS_Init_sec_context call

   Inputs:

   o  claimant_cred_handle OCTET STRING, -NULL specifies "use
      default"

   o  input_context_handle INTEGER, -0 specifies "none assigned
      yet"

   o  targ_name INTERNAL NAME,

   o  mech_type OBJECT IDENTIFIER, -NULL parameter specifies "use
      default"

   o  deleg_req_flag BOOLEAN,



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RFC 1508               Generic Security Interface         September 1993


   o  mutual_req_flag BOOLEAN,

   o  replay_det_req_flag BOOLEAN,

   o  sequence_req_flag BOOLEAN,

   o  lifetime_req INTEGER,-0 specifies default lifetime

   o  chan_bindings OCTET STRING,

   o  input_token OCTET STRING-NULL or token received from target

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  output_context_handle INTEGER,

   o  mech_type OBJECT IDENTIFIER, -actual mechanism always
      indicated, never NULL

   o  output_token OCTET STRING, -NULL or token to pass to context
      target

   o  deleg_state BOOLEAN,

   o  mutual_state BOOLEAN,

   o  replay_det_state BOOLEAN,

   o  sequence_state BOOLEAN,

   o  conf_avail BOOLEAN,

   o  integ_avail BOOLEAN,

   o  lifetime_rec INTEGER - in seconds, or reserved value for
      INDEFINITE

   This call may block pending network interactions for those mech_types
   in which an authentication server or other network entity must be
   consulted on behalf of a context initiator in order to generate an
   output_token suitable for presentation to a specified target.

   Return major_status codes:




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   o  GSS_COMPLETE indicates that context-level information was
      successfully initialized, and that the returned output_token will
      provide sufficient information for the target to perform per-
      message processing on the newly-established context.

   o  GSS_CONTINUE_NEEDED indicates that control information in the
      returned output_token must be sent to the target, and that a reply
      must be received and passed as the input_token argument to a
      continuation call to GSS_Init_sec_context(),  before per-message
      processing can be performed in conjunction with this context.

   o  GSS_DEFECTIVE_TOKEN indicates that consistency checks performed on
      the input_token failed, preventing further processing from being
      performed based on that token.

   o  GSS_DEFECTIVE_CREDENTIAL indicates that consistency checks
      performed on the credential structure referenced by
      claimant_cred_handle failed, preventing further processing from
      being performed using that credential structure.

   o  GSS_BAD_SIG indicates that the received input_token contains an
      incorrect signature, so context setup cannot be accomplished.

   o  GSS_NO_CRED indicates that no context was established, either
      because the input cred_handle was invalid, because the referenced
      credentials are valid for context acceptor use only, or because
      the caller lacks authorization to access the referenced
      credentials.

   o  GSS_CREDENTIALS_EXPIRED indicates that the credentials provided
      through the input claimant_cred_handle argument are no longer
      valid, so context establishment cannot be completed.

   o  GSS_BAD_BINDINGS indicates that a mismatch between the caller-
      provided chan_bindings and those extracted from the input_token
      was detected, signifying a security-relevant event and preventing
      context establishment. (This result will be returned by
      GSS_Init_sec_context only for contexts where mutual_state is
      TRUE.)

   o  GSS_NO_CONTEXT indicates that no valid context was recognized for
      the input context_handle provided; this major status will be
      returned only for successor calls following GSS_CONTINUE_NEEDED
      status returns.

   o  GSS_BAD_NAMETYPE indicates that the provided targ_name is of a
      type uninterpretable or unsupported by the supporting GSS-API
      implementation, so context establishment cannot be completed.



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RFC 1508               Generic Security Interface         September 1993


   o  GSS_BAD_NAME indicates that the provided targ_name is inconsistent
      in terms of internally-incorporated type specifier information, so
      context establishment cannot be accomplished.

   o  GSS_FAILURE indicates that context setup could not be accomplished
      for reasons unspecified at the GSS-API level, and that no
      interface-defined recovery action is available.

   This routine is used by a context initiator, and ordinarily emits one
   (or, for the case of a multi-step exchange, more than one)
   output_token suitable for use by the target within the selected
   mech_type's protocol. Using information in the credentials structure
   referenced by claimant_cred_handle, GSS_Init_sec_context()
   initializes the data structures required to establish a security
   context with target targ_name. The claimant_cred_handle must
   correspond to the same valid credentials structure on the initial
   call to GSS_Init_sec_context()  and on any successor calls resulting
   from GSS_CONTINUE_NEEDED status returns; different protocol sequences
   modeled by the GSS_CONTINUE_NEEDED mechanism will require access to
   credentials at different points in the context establishment
   sequence.

   The input_context_handle argument is 0, specifying "not yet
   assigned", on the first GSS_Init_sec_context()  call relating to a
   given context. That call returns an output_context_handle for future
   references to this context. When continuation attempts to
   GSS_Init_sec_context()  are needed to perform context establishment,
   the previously-returned non-zero handle value is entered into the
   input_context_handle argument and will be echoed in the returned
   output_context_handle argument. On such continuation attempts (and
   only on continuation attempts) the input_token value is used, to
   provide the token returned from the context's target.

   The chan_bindings argument is used by the caller to provide
   information binding the security context to security-related
   characteristics (e.g., addresses, cryptographic keys) of the
   underlying communications channel. See Section 1.1.6 of this document
   for more discussion of this argument's usage.

   The input_token argument contains a message received from the target,
   and is significant only on a call to GSS_Init_sec_context() which
   follows a previous return indicating GSS_CONTINUE_NEEDED
   major_status.

   It is the caller's responsibility to establish a communications path
   to the target, and to transmit any returned output_token (independent
   of the accompanying returned major_status value) to the target over
   that path. The output_token can, however, be transmitted along with



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RFC 1508               Generic Security Interface         September 1993


   the first application-provided input message to be processed by
   GSS_Sign() or GSS_Seal() in conjunction with a successfully-
   established context.

   The initiator may request various context-level functions through
   input flags: the deleg_req_flag requests delegation of access rights,
   the mutual_req_flag requests mutual authentication, the
   replay_det_req_flag requests that replay detection features be
   applied to messages transferred on the established context, and the
   sequence_req_flag requests that sequencing be enforced. (See Section
   1.2.3 for more information on replay detection and sequencing
   features.)

   Not all of the optionally-requestable features will be available in
   all underlying mech_types; the corresponding return state values
   (deleg_state, mutual_state, replay_det_state, sequence_state)
   indicate, as a function of mech_type processing capabilities and
   initiator-provided input flags, the set of features which will be
   active on the context. These state indicators' values are undefined
   unless the routine's major_status indicates COMPLETE. Failure to
   provide the precise set of features requested by the caller does not
   cause context establishment to fail; it is the caller's prerogative
   to delete the context if the feature set provided is unsuitable for
   the caller's use.  The returned mech_type value indicates the
   specific mechanism employed on the context, and will never indicate
   the value for "default".

   The conf_avail return value indicates whether the context supports
   per-message confidentiality services, and so informs the caller
   whether or not a request for encryption through the conf_req_flag
   input to GSS_Seal() can be honored. In similar fashion, the
   integ_avail return value indicates whether per-message integrity
   services are available (through either GSS_Sign() or GSS_Seal()) on
   the established context.

   The lifetime_req input specifies a desired upper bound for the
   lifetime of the context to be established, with a value of 0 used to
   request a default lifetime. The lifetime_rec return value indicates
   the length of time for which the context will be valid, expressed as
   an offset from the present; depending on mechanism capabilities,
   credential lifetimes, and local policy, it may not correspond to the
   value requested in lifetime_req.  If no constraints on context
   lifetime are imposed, this may be indicated by return