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RFC 1509 - Generic Security Service API : C-bindings


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Network Working Group                                            J. Wray
Request for Comments: 1509                 Digital Equipment Corporation
                                                          September 1993

               Generic Security Service API : C-bindings

Status of this Memo

   This RFC specifies an Internet standards track protocol for the
   Internet community, and requests discussion and suggestions for
   improvements.  Please refer to the current edition of the "Internet
   Official Protocol Standards" for the standardization state and status
   of this protocol.  Distribution of this memo is unlimited.

Abstract

   This document specifies C language bindings for the Generic Security
   Service Application Program Interface (GSS-API), which is described
   at a language-independent conceptual level in other documents.

   The Generic Security Service Application Programming Interface (GSS-
   API) provides security services to its callers, and is intended for
   implementation atop alternative underlying cryptographic mechanisms.
   Typically, GSS-API callers will be application protocols into which
   security enhancements are integrated through invocation of services
   provided by the GSS-API. The GSS-API allows a caller application to
   authenticate a principal identity associated with a peer application,
   to delegate rights to a peer, and to apply security services such as
   confidentiality and integrity on a per-message basis.

1. INTRODUCTION

   The Generic Security Service Application Programming Interface [1]
   provides security services to calling applications.  It allows a
   communicating application to authenticate the user associated with
   another application, to delegate rights to another application, and
   to apply security services such as confidentiality and integrity on a
   per-message basis.

   There are four stages to using the GSSAPI:

   (a) The application acquires a set of credentials with which it may
       prove its identity to other processes.  The application's
       credentials vouch for its global identity, which may or may not
       be related to the local username under which it is running.

   (b) A pair of communicating applications establish a joint security
       context using their credentials.  The security context is a
       pair of GSSAPI data structures that contain shared state
       information, which is required in order that per-message
       security services may be provided.  As part of the
       establishment of a security context, the context initiator is
       authenticated to the responder, and may require that the
       responder is authenticated in turn.  The initiator may
       optionally give the responder the right to initiate further
       security contexts.  This transfer of rights is termed
       delegation, and is achieved by creating a set of credentials,
       similar to those used by the originating application, but which
       may be used by the responder.  To establish and maintain the
       shared information that makes up the security context, certain
       GSSAPI calls will return a token data structure, which is a
       cryptographically protected opaque data type.  The caller of
       such a GSSAPI routine is responsible for transferring the token
       to the peer application, which should then pass it to a
       corresponding GSSAPI routine which will decode it and extract
       the information.

   (c) Per-message services are invoked to apply either:

       (i) integrity and data origin authentication, or

       (ii) confidentiality, integrity and data origin authentication
            to application data, which are treated by GSSAPI as
            arbitrary octet-strings.  The application transmitting a
            message that it wishes to protect will call the appropriate
            GSSAPI routine (sign or seal) to apply protection, specifying
            the appropriate security context, and send the result to the
            receiving application.  The receiver will pass the received
            data to the corresponding decoding routine (verify or unseal)
            to remove the protection and validate the data.

   (d) At the completion of a communications session (which may extend
       across several connections), the peer applications call GSSAPI
       routines to delete the security context.  Multiple contexts may
       also be used (either successively or simultaneously) within a
       single communications association.

2. GSSAPI Routines

   This section lists the functions performed by each of the GSSAPI
   routines and discusses their major parameters, describing how they
   are to be passed to the routines.  The routines are listed in figure
   4-1.

                      Figure 4-1  GSSAPI Routines

            Routine                               Function

            gss_acquire_cred               Assume a global identity

            gss_release_cred               Discard credentials

            gss_init_sec_context           Initiate a security context
                                           with a peer application

            gss_accept_sec_context         Accept a security context
                                           initiated by a peer
                                           application

            gss_process_context_token      Process a token on a security
                                           context from a peer
                                           application

            gss_delete_sec_context         Discard a security context

            gss_context_time               Determine for how long a
                                           context will remain valid

            gss_sign                       Sign a message; integrity
                                           service

            gss_verify                     Check signature on a message

            gss_seal                       Sign (optionally encrypt) a
                                           message; confidentiality
                                           service

            gss_unseal                     Verify (optionally decrypt)
                                           message

            gss_display_status             Convert an API status code
                                           to text

            gss_indicate_mechs             Determine underlying
                                           authentication mechanism

            gss_compare_name               Compare two internal-form
                                           names

            gss_display_name               Convert opaque name to text

            gss_import_name                Convert a textual name to
                                           internal-form

            gss_release_name               Discard an internal-form
                                           name

            gss_release_buffer             Discard a buffer

            gss_release_oid_set            Discard a set of object
                                           identifiers

            gss_inquire_cred               Determine information about
                                           a credential

   Individual GSSAPI implementations may augment these routines by
   providing additional mechanism-specific routines if required
   functionality is not available from the generic forms.  Applications
   are encouraged to use the generic routines wherever possible on
   portability grounds.

2.1. Data Types and Calling Conventions

   The following conventions are used by the GSSAPI:

2.1.1. Structured data types

   Wherever these GSSAPI C-bindings describe structured data, only
   fields that must be provided by all GSSAPI implementation are
   documented.  Individual implementations may provide additional
   fields, either for internal use within GSSAPI routines, or for use by
   non-portable applications.

2.1.2. Integer types

   GSSAPI defines the following integer data type:

                 OM_uint32      32-bit unsigned integer

   Where guaranteed minimum bit-count is important, this portable data
   type is used by the GSSAPI routine definitions. Individual GSSAPI
   implementations will include appropriate typedef definitions to map
   this type onto a built-in data type.

2.1.3. String and similar data

   Many of the GSSAPI routines take arguments and return values that
   describe contiguous multiple-byte data.  All such data is passed
   between the GSSAPI and the caller using the gss_buffer_t data type.

   This data type is a pointer to a buffer descriptor, which consists of
   a length field that contains the total number of bytes in the datum,
   and a value field which contains a pointer to the actual datum:

                 typedef struct gss_buffer_desc_struct {
                    size_t  length;
                    void    *value;
                 } gss_buffer_desc, *gss_buffer_t;

   Storage for data passed to the application by a GSSAPI routine using
   the gss_buffer_t conventions is allocated by the GSSAPI routine.  The
   application may free this storage by invoking the gss_release_buffer
   routine.  Allocation of the gss_buffer_desc object is always the
   responsibility of the application;  Unused gss_buffer_desc objects
   may be initialized to the value GSS_C_EMPTY_BUFFER.

2.1.3.1. Opaque data types

   Certain multiple-word data items are considered opaque data types at
   the GSSAPI, because their internal structure has no significance
   either to the GSSAPI or to the caller.  Examples of such opaque data
   types are the input_token parameter to gss_init_sec_context (which is
   opaque to the caller), and the input_message parameter to gss_seal
   (which is opaque to the GSSAPI).  Opaque data is passed between the
   GSSAPI and the application using the gss_buffer_t datatype.

2.1.3.2. Character strings

   Certain multiple-word data items may be regarded as simple ISO
   Latin-1 character strings.  An example of this is the
   input_name_buffer parameter to gss_import_name.  Some GSSAPI routines
   also return character strings.  Character strings are passed between
   the application and the GSSAPI using the gss_buffer_t datatype,
   defined earlier.

2.1.4. Object Identifiers

   Certain GSSAPI procedures take parameters of the type gss_OID, or
   Object identifier.  This is a type containing ISO-defined tree-
   structured values, and is used by the GSSAPI caller to select an
   underlying security mechanism.  A value of type gss_OID has the
   following structure:

                 typedef struct gss_OID_desc_struct {
                    OM_uint32 length;
                    void      *elements;
                 } gss_OID_desc, *gss_OID;

   The elements field of this structure points to the first byte of an
   octet string containing the ASN.1 BER encoding of the value of the
   gss_OID.  The length field contains the number of bytes in this
   value.  For example, the  gss_OID value corresponding to {iso(1)
   identified- oganization(3) icd-ecma(12) member-company(2) dec(1011)
   cryptoAlgorithms(7) SPX(5)} meaning SPX (Digital's X.509
   authentication mechanism) has a length field of 7 and an elements
   field pointing to seven octets containing the following octal values:
   53,14,2,207,163,7,5. GSSAPI implementations should provide constant
   gss_OID values to allow callers to request any supported mechanism,
   although applications are encouraged on portability grounds to accept
   the default mechanism.   gss_OID values should also be provided to
   allow applications to specify particular name types (see section
   2.1.10).  Applications should treat gss_OID_desc values returned by
   GSSAPI routines as read-only.  In particular, the application should
   not attempt to deallocate them.  The gss_OID_desc datatype is
   equivalent to the X/Open OM_object_identifier datatype [2].

2.1.5. Object Identifier Sets

   Certain GSSAPI procedures take parameters of the type gss_OID_set.
   This type represents one or more object identifiers (section 2.1.4).
   A gss_OID_set object has the following structure:

                 typedef struct gss_OID_set_desc_struct {
                    int       count;
                    gss_OID   elements;
                 } gss_OID_set_desc, *gss_OID_set;

   The count field contains the number of OIDs within the set.  The
   elements field is a pointer to an array of gss_OID_desc objects, each
   of which describes a single OID. gss_OID_set values are used to name
   the available mechanisms supported by the GSSAPI, to request the use
   of specific mechanisms, and to indicate which mechanisms a given
   credential supports.  Storage associated with gss_OID_set values
   returned to the application by the GSSAPI may be deallocated by the
   gss_release_oid_set routine.

2.1.6. Credentials

   A credential handle is a caller-opaque atomic datum that identifies a
   GSSAPI credential data structure.  It is represented by the caller-
   opaque type gss_cred_id_t, which may be implemented as either an
   arithmetic or a pointer type.  Credentials describe a principal, and
   they give their holder the ability to act as that principal.  The
   GSSAPI does not make the actual credentials available to
   applications; instead the credential handle is used to identify a
   particular credential, held internally by GSSAPI or underlying

   mechanism.  Thus the credential handle contains no security-relavent
   information, and requires no special protection by the application.
   Depending on the implementation, a given credential handle may refer
   to different credentials when presented to the GSSAPI by different
   callers.  Individual GSSAPI implementations should define both the
   scope of a credential handle and the scope of a credential itself
   (which must be at least as wide as that of a handle).  Possibilities
   for credential handle scope include the process that acquired the
   handle, the acquiring process and its children, or all processes
   sharing some local identification information (e.g., UID).  If no
   handles exist by which a given credential may be reached, the GSSAPI
   may delete the credential.

   Certain routines allow credential handle parameters to be omitted to
   indicate the use of a default credential.  The mechanism by which a
   default credential is established and its scope should be defined by
   the individual GSSAPI implementation.

2.1.7. Contexts

   The gss_ctx_id_t data type contains a caller-opaque atomic value that
   identifies one end of a GSSAPI security context.  It may be
   implemented as either an arithmetic or a pointer type. Depending on
   the implementation, a given gss_ctx_id_t value may refer to different
   GSSAPI security contexts when presented to the GSSAPI by different
   callers.  The security context holds state information about each end
   of a peer communication, including cryptographic state information.
   Individual GSSAPI implementations should define the scope of a
   context.  Since no way is provided by which a new gss_ctx_id_t value
   may be obtained for an existing context, the scope of a context
   should be the same as the scope of a gss_ctx_id_t.

2.1.8. Authentication tokens

   A token is a caller-opaque type that GSSAPI uses to maintain
   synchronization between the context data structures at each end of a
   GSSAPI security context.  The token is a cryptographically protected
   bit-string, generated by the underlying mechanism at one end of a
   GSSAPI security context for use by the peer mechanism at the other
   end.  Encapsulation (if required) and transfer of the token are the
   responsibility of the peer applications.  A token is passed between
   the GSSAPI and the application using the gss_buffer_t conventions.

2.1.9. Status values

   One or more status codes are returned by each GSSAPI routine.  Two
   distinct sorts of status codes are returned.  These are termed GSS
   status codes and Mechanism status codes.

2.1.9.1. GSS status codes

   GSSAPI routines return GSS status codes as their OM_uint32 function
   value.  These codes indicate errors that are independent of the
   underlying mechanism used to provide the security service.  The
   errors that can be indicated via a GSS status code are either generic
   API routine errors (errors that are defined in the GSSAPI
   specification) or calling errors (errors that are specific to these
   bindings).

   A GSS status code can indicate a single fatal generic API error from
   the routine and a single calling error.  In addition, supplementary
   status information may be indicated via the setting of bits in the
   supplementary info field of a GSS status code.

   These errors are encoded into the 32-bit GSS status code as follows:

      MSB                                                        LSB
      |------------------------------------------------------------|
      | Calling Error | Routine Error  |    Supplementary Info     |
      |------------------------------------------------------------|
   Bit 31           24 23            16 15                        0

   Hence if a GSSAPI routine returns a GSS status code whose upper 16
   bits contain a non-zero value, the call failed.  If the calling error
   field is non-zero, the invoking application's call of the routine was
   erroneous.  Calling errors are defined in table 5-1.  If the routine
   error field is non-zero, the routine failed for one of the routine-
   specific reasons listed below in table 5-2.  Whether or not the upper
   16 bits indicate a failure or a success, the routine may indicate
   additional information by setting bits in the supplementary info
   field of the status code.  The meaning of individual bits is listed
   below in table 5-3.

                     Table 5-1  Calling Errors

              Name                    Value in        Meaning
                                        Field
         GSS_S_CALL_INACCESSIBLE_READ     1           A required input
                                                      parameter could
                                                      not be read.
         GSS_S_CALL_INACCESSIBLE_WRITE    2           A required output
                                                      parameter could
                                                      not be written.
         GSS_S_CALL_BAD_STRUCTURE         3           A parameter was
                                                      malformed

                     Table 5-2  Routine Errors

               Name             Value in       Meaning
                                 Field

         GSS_S_BAD_MECH             1      An unsupported mechanism was
                                           requested
         GSS_S_BAD_NAME             2      An invalid name was supplied
         GSS_S_BAD_NAMETYPE         3      A supplied name was of an
                                           unsupported type
         GSS_S_BAD_BINDINGS         4      Incorrect channel bindings
                                           were supplied
         GSS_S_BAD_STATUS           5      An invalid status code was
                                           supplied

         GSS_S_BAD_SIG              6      A token had an invalid
                                           signature
         GSS_S_NO_CRED              7      No credentials were supplied
         GSS_S_NO_CONTEXT           8      No context has been
                                           established
         GSS_S_DEFECTIVE_TOKEN      9      A token was invalid
         GSS_S_DEFECTIVE_CREDENTIAL 10     A credential was invalid
         GSS_S_CREDENTIALS_EXPIRED  11     The referenced credentials
                                           have expired
         GSS_S_CONTEXT_EXPIRED      12     The context has expired
         GSS_S_FAILURE              13     Miscellaneous failure
                                           (see text)

                     Table 5-3  Supplementary Status Bits

         Name                Bit Number         Meaning
         GSS_S_CONTINUE_NEEDED   0 (LSB)  The routine must be called
                                          again to complete its
                                          function.
                                          See routine documentation for
                                          detailed description.
         GSS_S_DUPLICATE_TOKEN   1        The token was a duplicate of
                                          an earlier token
         GSS_S_OLD_TOKEN         2        The token's validity period
                                          has expired
         GSS_S_UNSEQ_TOKEN       3        A later token has already been
                                          processed

   The routine documentation also uses the name GSS_S_COMPLETE, which is
   a zero value, to indicate an absence of any API errors or
   supplementary information bits.

   All GSS_S_xxx symbols equate to complete OM_uint32 status codes,
   rather than to bitfield values.  For example, the actual value of the
   symbol GSS_S_BAD_NAMETYPE (value 3 in the routine error field) is 3
   << 16.

   The macros GSS_CALLING_ERROR(), GSS_ROUTINE_ERROR() and
   GSS_SUPPLEMENTARY_INFO() are provided, each of which takes a GSS
   status code and removes all but the relevant field.  For example, the
   value obtained by applying GSS_ROUTINE_ERROR to a status code removes
   the calling errors and supplementary info fields, leaving only the
   routine errors field.  The values delivered by these macros may be
   directly compared with a GSS_S_xxx symbol of the appropriate type.
   The macro GSS_ERROR() is also provided, which when applied to a GSS
   status code returns a non-zero value if the status code indicated a
   calling or routine error, and a zero value otherwise.

   A GSSAPI implementation may choose to signal calling errors in a
   platform-specific manner instead of, or in addition to the routine
   value; routine errors and supplementary info should be returned via
   routine status values only.

2.1.9.2. Mechanism-specific status codes

   GSSAPI routines return a minor_status parameter, which is used to
   indicate specialized errors from the underlying security mechanism.
   This parameter may contain a single mechanism-specific error,
   indicated by a OM_uint32 value.

   The minor_status parameter will always be set by a GSSAPI routine,
   even if it returns a calling error or one of the generic API errors
   indicated above as fatal, although other output parameters may remain
   unset in such cases.  However, output parameters that are expected to
   return pointers to storage allocated by a routine must always set set
   by the routine, even in the event of an error, although in such cases
   the GSSAPI routine may elect to set the returned parameter value to
   NULL to indicate that no storage was actually allocated.  Any length
   field associated with such pointers (as in a gss_buffer_desc
   structure) should also be set to zero in such cases.

   The GSS status code GSS_S_FAILURE is used to indicate that the
   underlying mechanism detected an error for which no specific GSS
   status code is defined.  The mechanism status code will provide more
   details about the error.

2.1.10. Names

   A name is used to identify a person or entity.  GSSAPI authenticates
   the relationship between a name and the entity claiming the name.

   Two distinct representations are defined for names:

        (a) A printable form, for presentation to a user

        (b) An internal form, for presentation at the API

   The syntax of a printable name is defined by the GSSAPI
   implementation, and may be dependent on local system configuration,
   or on individual user preference.  The internal form provides a
   canonical representation of the name that is independent of
   configuration.

   A given GSSAPI implementation may support names drawn from multiple
   namespaces.  In such an implementation, the internal form of the name
   must include fields that identify the namespace from which the name
   is drawn.  The namespace from which a printable name is drawn is
   specified by an accompanying object identifier.

   Routines (gss_import_name and  gss_display_name) are provided to
   convert names between their printable representations and the
   gss_name_t type.  gss_import_name may support multiple syntaxes for
   each supported namespace, allowing users the freedom to choose a
   preferred name representation.  gss_display_name should use an
   implementation-chosen preferred syntax for each supported name-type.

   Comparison of internal-form names is accomplished via the
   gss_compare_names routine.  This removes the need for the application
   program to understand the syntaxes of the various printable names
   that a given GSSAPI implementation may support.

   Storage is allocated by routines that return gss_name_t values.  A
   procedure, gss_release_name, is provided to free storage associated
   with a name.

2.1.11. Channel Bindings

   GSSAPI supports the use of user-specified tags to identify a given
   context to the peer application.  These tags are used to identify the
   particular communications channel that carries the context.  Channel
   bindings are communicated to the GSSAPI using the following
   structure:

                 typedef struct gss_channel_bindings_struct {
                    OM_uint32       initiator_addrtype;
                    gss_buffer_desc initiator_address;
                    OM_uint32       acceptor_addrtype;
                    gss_buffer_desc acceptor_address;
                    gss_buffer_desc application_data;
                 } *gss_channel_bindings_t;

   The initiator_addrtype and acceptor_addrtype fields denote the type
   of addresses contained in the initiator_address and acceptor_address
   buffers.  The address type should be one of the following:

          GSS_C_AF_UNSPEC      Unspecified address type
          GSS_C_AF_LOCAL       Host-local address type
          GSS_C_AF_INET        DARPA Internet address type
          GSS_C_AF_IMPLINK     ARPAnet IMP address type (eg IP)
          GSS_C_AF_PUP         pup protocols (eg BSP) address type
          GSS_C_AF_CHAOS       MIT CHAOS protocol address type
          GSS_C_AF_NS          XEROX NS address type
          GSS_C_AF_NBS         nbs address type
          GSS_C_AF_ECMA        ECMA address type
          GSS_C_AF_DATAKIT     datakit protocols address type
          GSS_C_AF_CCITT       CCITT protocols (eg X.25)
          GSS_C_AF_SNA         IBM SNA address type
          GSS_C_AF_DECnet      DECnet address type
          GSS_C_AF_DLI         Direct data link interface address type
          GSS_C_AF_LAT         LAT address type
          GSS_C_AF_HYLINK      NSC Hyperchannel address type
          GSS_C_AF_APPLETALK   AppleTalk address type
          GSS_C_AF_BSC         BISYNC 2780/3780 address type
          GSS_C_AF_DSS         Distributed system services address type
          GSS_C_AF_OSI         OSI TP4 address type
          GSS_C_AF_X25         X25
          GSS_C_AF_NULLADDR    No address specified

   Note that these name address families rather than specific addressing
   formats.  For address families that contain several alternative
   address forms, the initiator_address and acceptor_address fields must
   contain sufficient information to determine which address form is
   used.  When not otherwise specified, addresses should be specified in
   network byte-order.

   Conceptually, the GSSAPI concatenates the initiator_addrtype,
   initiator_address, acceptor_addrtype, acceptor_address and
   application_data to form an octet string.  The mechanism signs this
   octet string, and binds the signature to the context establishment
   token emitted by gss_init_sec_context.  The same bindings are
   presented by the context acceptor to gss_accept_sec_context, and a

   signature is calculated in the same way.  The calculated signature is
   compared with that found in the token, and if the signatures differ,
   gss_accept_sec_context will return a GSS_S_BAD_BINDINGS error, and
   the context will not be established.  Some mechanisms may include the
   actual channel binding data in the token (rather than just a
   signature); applications should therefore not use confidential data
   as channel-binding components.  Individual mechanisms may impose
   additional constraints on addresses and address types that may appear
   in channel bindings.  For example, a mechanism may verify that the
   initiator_address field of the channel bindings presented to
   gss_init_sec_context contains the correct network address of the host
   system.

2.1.12. Optional parameters

   Various parameters are described as optional.  This means that they
   follow a convention whereby a default value may be requested.  The
   following conventions are used for omitted parameters.  These
   conventions apply only to those parameters that are explicitly
   documented as optional.

2.1.12.1. gss_buffer_t types

   Specify GSS_C_NO_BUFFER as a value.  For an input parameter this
   signifies that default behavior is requested, while for an output
   parameter it indicates that the information that would be returned
   via the parameter is not required by the application.

2.1.12.2. Integer types (input)

   Individual parameter documentation lists values to be used to
   indicate default actions.

2.1.12.3. Integer types (output)

   Specify NULL as the value for the pointer.

2.1.12.4. Pointer types

   Specify NULL as the value.

2.1.12.5. Object IDs

   Specify GSS_C_NULL_OID as the value.

2.1.12.6. Object ID Sets

   Specify GSS_C_NULL_OID_SET as the value.

2.1.12.7. Credentials

   Specify GSS_C_NO_CREDENTIAL to use the default credential handle.

2.1.12.8. Channel Bindings

   Specify GSS_C_NO_CHANNEL_BINDINGS to indicate that channel bindings
   are not to be used.

3. GSSAPI routine descriptions

2.1. gss_acquire_cred

      OM_uint32  gss_acquire_cred (
                     OM_uint32 *     minor_status,
                     gss_name_t      desired_name,
                     OM_uint32       time_req,
                     gss_OID_set     desired_mechs,
                     int             cred_usage,
                     gss_cred_id_t * output_cred_handle,
                     gss_OID_set *   actual_mechs,
                      OM_int32 *      time_rec)
   Purpose:

   Allows an application to acquire a handle for a pre-existing
   credential by name.  GSSAPI implementations must impose a local
   access-control policy on callers of this routine to prevent
   unauthorized callers from acquiring credentials to which they are not
   entitled.  This routine is not intended to provide a "login to the
   network" function, as such a function would result in the creation of
   new credentials rather than merely acquiring a handle to existing
   credentials.  Such functions, if required, should be defined in
   implementation-specific extensions to the API.

   If credential acquisition is time-consuming for a mechanism, the
   mechanism may chooses to delay the actual acquisition until the
   credential is required (e.g., by gss_init_sec_context or
   gss_accept_sec_context).  Such mechanism-specific implementation
   decisions should be invisible to the calling application; thus a call
   of gss_inquire_cred immediately following the call of
   gss_acquire_cred must return valid credential data, and may therefore
   incur the overhead of a deferred credential acquisition.

   Parameters:

      desired_name      gss_name_t, read
                        Name of principal whose credential
                        should be acquired

      time_req          integer, read
                        number of seconds that credentials
                        should remain valid

      desired_mechs     Set of Object IDs, read
                        set of underlying security mechanisms that
                        may be used.  GSS_C_NULL_OID_SET may be used
                        to obtain an implementation-specific default.

      cred_usage        integer, read
                        GSS_C_BOTH - Credentials may be used
                                     either to initiate or accept
                                     security contexts.
                        GSS_C_INITIATE - Credentials will only be
                                         used to initiate security
                                         contexts.
                        GSS_C_ACCEPT - Credentials will only be used to
                                       accept security contexts.

      output_cred_handle   gss_cred_id_t, modify
                           The returned credential handle.

      actual_mechs      Set of Object IDs, modify, optional
                        The set of mechanisms for which the
                        credential is valid.  Specify NULL
                        if not required.

      time_rec          Integer, modify, optional
                        Actual number of seconds for which the
                        returned credentials will remain valid.  If the
                        implementation does not support expiration of
                        credentials, the value GSS_C_INDEFINITE will
                        be returned. Specify NULL if not required

      minor_status      Integer, modify
                        Mechanism specific status code.
   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_BAD_MECH    Unavailable mechanism requested

      GSS_S_BAD_NAMETYPE Type contained within desired_name parameter is
                        not supported

      GSS_S_BAD_NAME    Value supplied for desired_name parameter is

                        ill-formed.

      GSS_S_FAILURE     Unspecified failure.  The minor_status parameter
                        contains more detailed information

3.2. gss_release_cred

      OM_uint32  gss_release_cred (
                     OM_uint32 *     minor_status,
                     gss_cred_id_t * cred_handle)

   Purpose:

   Informs GSSAPI that the specified credential handle is no longer
   required by the process.  When all processes have released a
   credential, it will be deleted.

   Parameters:

      cred_handle       gss_cred_id_t, modify, optional
                        buffer containing opaque credential
                        handle.  If  GSS_C_NO_CREDENTIAL  is supplied,
                        the default credential will be released

      minor_status      integer, modify
                        Mechanism specific status code.

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_NO_CRED     Credentials could not be accessed.

3.3. gss_init_sec_context

      OM_uint32  gss_init_sec_context (
                     OM_uint32 *     minor_status,
                     gss_cred_id_t   claimant_cred_handle,
                     gss_ctx_id_t *  context_handle,
                     gss_name_t      target_name,
                     gss_OID         mech_type,
                     int             req_flags,
                     int             time_req,
                     gss_channel_bindings_t
                                     input_chan_bindings,
                     gss_buffer_t    input_token
                     gss_OID *       actual_mech_type,
                     gss_buffer_t    output_token,
                     int *           ret_flags,
                     OM_uint32 *     time_rec )

   Purpose:

   Initiates the establishment of a security context between the
   application and a remote peer.  Initially, the input_token parameter
   should be specified as GSS_C_NO_BUFFER.  The routine may return a
   output_token which should be transferred to the peer application,
   where the peer application will present it to gss_accept_sec_context.
   If no token need be sent, gss_init_sec_context will indicate this by
   setting the length field of the output_token argument to zero.  To
   complete the context establishment, one or more reply tokens may be
   required from the peer application; if so, gss_init_sec_context will
   return a status indicating GSS_S_CONTINUE_NEEDED in which case it
   should be called again when the reply token is received from the peer
   application, passing the token to gss_init_sec_context via the
   input_token parameters.

   The values returned via the ret_flags and time_rec parameters are not
   defined unless the routine returns GSS_S_COMPLETE.

   Parameters:

      claimant_cred_handle  gss_cred_id_t, read, optional
                            handle for credentials claimed.  Supply
                            GSS_C_NO_CREDENTIAL to use default
                            credentials.

      context_handle    gss_ctx_id_t, read/modify
                        context handle for new context.  Supply
                        GSS_C_NO_CONTEXT for first call; use value
                        returned by first call in continuation calls.

      target_name       gss_name_t, read
                        Name of target

      mech_type         OID, read, optional
                        Object ID of desired mechanism. Supply
                        GSS_C_NULL_OID to obtain an implementation
                        specific default

      req_flags         bit-mask, read
                        Contains four independent flags, each of
                        which requests that the context support a
                        specific service option.  Symbolic
                        names are provided for each flag, and the
                        symbolic names corresponding to the required
                        flags should be logically-ORed
                        together to form the bit-mask value.  The
                        flags are:

                        GSS_C_DELEG_FLAG
                              True - Delegate credentials to remote peer
                              False - Don't delegate
                        GSS_C_MUTUAL_FLAG
                              True - Request that remote peer
                                     authenticate itself
                              False - Authenticate self to remote peer
                                      only
                        GSS_C_REPLAY_FLAG
                              True - Enable replay detection for signed
                                     or sealed messages
                              False - Don't attempt to detect
                                      replayed messages
                        GSS_C_SEQUENCE_FLAG
                              True - Enable detection of out-of-sequence
                                     signed or sealed messages
                              False - Don't attempt to detect
                                      out-of-sequence messages

      time_req          integer, read
                        Desired number of seconds for which context
                        should remain valid.  Supply 0 to request a
                        default validity period.

      input_chan_bindings     channel bindings, read
                              Application-specified bindings.  Allows
                              application to securely bind channel
                              identification information to the security
                              context.

      input_token       buffer, opaque, read, optional (see text)
                        Token received from peer application.
                        Supply GSS_C_NO_BUFFER on initial call.

      actual_mech_type  OID, modify
                        actual mechanism used.

      output_token      buffer, opaque, modify
                        token to be sent to peer application.  If
                        the length field of the returned buffer is
                        zero, no token need be sent to the peer
                        application.

      ret_flags         bit-mask, modify
                        Contains six independent flags, each of which
                        indicates that the context supports a specific
                        service option.  Symbolic names are provided
                        for each flag, and the symbolic names
                        corresponding to the required flags should be
                        logically-ANDed with the ret_flags value to test
                        whether a given option is supported by the
                        context.  The flags are:

                        GSS_C_DELEG_FLAG
                              True - Credentials were delegated to
                                     the remote peer
                              False - No credentials were delegated
                        GSS_C_MUTUAL_FLAG
                              True - Remote peer has been asked to
                                     authenticated itself
                              False - Remote peer has not been asked to
                                      authenticate itself
                        GSS_C_REPLAY_FLAG
                              True - replay of signed or sealed messages
                                     will be detected
                              False - replayed messages will not be
                                      detected
                        GSS_C_SEQUENCE_FLAG
                              True - out-of-sequence signed or sealed
                                     messages will be detected
                              False - out-of-sequence messages will not
                                      be detected
                        GSS_C_CONF_FLAG
                              True - Confidentiality service may be
                                     invoked by calling seal routine
                              False - No confidentiality service (via
                                      seal) available. seal will provide
                                      message encapsulation, data-origin

                                      authentication and integrity
                                      services only.
                        GSS_C_INTEG_FLAG
                              True - Integrity service may be invoked by
                                     calling either gss_sign or gss_seal
                                     routines.
                              False - Per-message integrity service
                                      unavailable.

      time_rec          integer, modify, optional
                        number of seconds for which the context
                        will remain valid. If the implementation does
                        not support credential expiration, the value
                        GSS_C_INDEFINITE will be returned.  Specify
                        NULL if not required.

      minor_status      integer, modify
                        Mechanism specific status code.

   Function value:

   GSS status code:

   GSS_S_COMPLETE    Successful completion

   GSS_S_CONTINUE_NEEDED Indicates that a token from the peer
                     application is required to complete thecontext, and
                     that gss_init_sec_context must be called again with
                     that token.

   GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks performed on
                     the input_token failed

   GSS_S_DEFECTIVE_CREDENTIAL Indicates that consistency checks
                     performed on the credential failed.

   GSS_S_NO_CRED     The supplied credentials were not valid for context
                     initiation, or the credential handle did not
                     reference any credentials.

   GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired

   GSS_S_BAD_BINDINGS The input_token contains different channel
                     bindings to those specified via the
                     input_chan_bindings parameter

   GSS_S_BAD_SIG     The input_token contains an invalid signature, or a
                     signature that could not be verified

   GSS_S_OLD_TOKEN   The input_token was too old.  This is a fatal error
                     during context establishment

   GSS_S_DUPLICATE_TOKEN The input_token is valid, but is a duplicate of
                     a token already processed.  This is a fatal error
                     during context establishment.

   GSS_S_NO_CONTEXT  Indicates that the supplied context handle did not
                     refer to a valid context

   GSS_S_BAD_NAMETYPE The provided target_name parameter contained an
                     invalid or unsupported type of name

   GSS_S_BAD_NAME    The provided target_name parameter was ill-formed.

   GSS_S_FAILURE     Failure.  See minor_status for more information

3.4. gss_accept_sec_context

      OM_uint32  gss_accept_sec_context (
                     OM_uint32 *     minor_status,
                     gss_ctx_id_t *  context_handle,
                     gss_cred_id_t   verifier_cred_handle,
                     gss_buffer_t    input_token_buffer
                     gss_channel_bindings_t
                                     input_chan_bindings,
                     gss_name_t *    src_name,
                     gss_OID *       mech_type,
                     gss_buffer_t    output_token,
                     int *           ret_flags,
                     OM_uint32 *     time_rec,
                     gss_cred_id_t * delegated_cred_handle)

   Purpose:

   Allows a remotely initiated security context between the application
   and a remote peer to be established.  The routine may return a
   output_token which should be transferred to the peer application,
   where the peer application will present it to gss_init_sec_context.
   If no token need be sent, gss_accept_sec_context will indicate this
   by setting the length field of the output_token argument to zero.  To
   complete the context establishment, one or more reply tokens may be
   required from the peer application; if so, gss_accept_sec_context
   will return a status flag of GSS_S_CONTINUE_NEEDED, in which case it
   should be called again when the reply token is received from the peer
   application, passing the token to gss_accept_sec_context via the
   input_token parameters.

   The values returned via the src_name, ret_flags, time_rec, and
   delegated_cred_handle parameters are not defined unless the routine
   returns GSS_S_COMPLETE.

   Parameters:

      context_handle    gss_ctx_id_t, read/modify
                        context handle for new context.  Supply
                        GSS_C_NO_CONTEXT for first call; use value
                        returned in subsequent calls.

      verifier_cred_handle    gss_cred_id_t, read, optional
                              Credential handle claimed by context
      acceptor.
                              Specify GSS_C_NO_CREDENTIAL to use default
                              credentials.  If GSS_C_NO_CREDENTIAL is
                              specified, but the caller has no default
                              credentials established, an
                              implementation-defined default credential
                              may be used.

      input_token_buffer      buffer, opaque, read
                              token obtained from remote application

      input_chan_bindings     channel bindings, read
                              Application-specified bindings.  Allows
                              application to securely bind channel
                              identification information to the security
                              context.

      src_name          gss_name_t, modify, optional
                        Authenticated name of context initiator.
                        After use, this name should be deallocated by
                        passing it to gss_release_name.  If not required,
                        specify NULL.

      mech_type         Object ID, modify
                        Security mechanism used.  The returned
                        OID value will be a pointer into static
                        storage, and should be treated as read-only
                        by the caller.

      output_token      buffer, opaque, modify
                        Token to be passed to peer application. If the
                        length field of the returned token buffer is 0,
                        then no token need be passed to the peer
                        application.

      ret_flags         bit-mask, modify
                        Contains six independent flags, each of
                        which indicates that the context supports a
                        specific service option.  Symbolic names are
                        provided for each flag, and the symbolic names
                        corresponding to the required flags
                        should be logically-ANDed with the ret_flags
                        value to test whether a given option is
                        supported by the context.  The flags are:
                        GSS_C_DELEG_FLAG
                              True - Delegated credentials are available
                                     via the delegated_cred_handle
                                     parameter
                              False - No credentials were delegated
                        GSS_C_MUTUAL_FLAG
                              True - Remote peer asked for mutual
                                     authentication
                              False - Remote peer did not ask for mutual
                                      authentication
                        GSS_C_REPLAY_FLAG
                              True - replay of signed or sealed messages
                                     will be detected
                              False - replayed messages will not be
                                      detected
                        GSS_C_SEQUENCE_FLAG
                              True - out-of-sequence signed or sealed
                                     messages will be detected
                              False - out-of-sequence messages will not
                                      be detected
                        GSS_C_CONF_FLAG
                              True - Confidentiality service may be
                                     invoked by calling seal routine
                              False - No confidentiality service (via
                                      seal) available. seal will
                                      provide message encapsulation,
                                      data-origin authentication and
                                      integrity services only.
                        GSS_C_INTEG_FLAG
                              True - Integrity service may be invoked
                                     by calling either gss_sign or
                                     gss_seal routines.
                              False - Per-message integrity service
                                      unavailable.

      time_rec          integer, modify, optional
                        number of seconds for which the context
                        will remain valid. Specify NULL if not required.

      delegated_cred_handle
                        gss_cred_id_t, modify
                        credential handle for credentials received from
                        context initiator.  Only valid if deleg_flag in
                        ret_flags is true.

      minor_status      integer, modify
                        Mechanism specific status code.

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_CONTINUE_NEEDED Indicates that a token from the peer
                        application is required to complete the context,
                        and that gss_accept_sec_context must be called
                        again with that token.

      GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks
                        performed on the input_token failed.

      GSS_S_DEFECTIVE_CREDENTIAL Indicates that consistency checks
                        performed on the credential failed.

      GSS_S_NO_CRED The supplied credentials were not valid for
                        context acceptance, or the credential handle
                        did not reference any credentials.

      GSS_S_CREDENTIALS_EXPIRED The referenced credentials have
                        expired.

      GSS_S_BAD_BINDINGS The input_token contains different channel
                        bindings to those specified via the
                        input_chan_bindings parameter.

      GSS_S_NO_CONTEXT Indicates that the supplied context handle did
                       not refer to a valid context.

      GSS_S_BAD_SIG    The input_token contains an invalid signature.

      GSS_S_OLD_TOKEN   The input_token was too old.  This is a fatal
                        error during context establishment.

      GSS_S_DUPLICATE_TOKEN The input_token is valid, but is a
                        duplicate of a token already processed.  This
                        is a fatal error during context establishment.

      GSS_S_FAILURE     Failure.  See minor_status for more information.

3.5. gss_process_context_token

      OM_uint32  gss_process_context_token (
                     OM_uint32 *     minor_status,
                     gss_ctx_id_t    context_handle,
                     gss_buffer_t    token_buffer)

   Purpose:

   Provides a way to pass a token to the security service.  Usually,
   tokens are associated either with context establishment (when they
   would be passed to gss_init_sec_context or gss_accept_sec_context) or
   with per-message security service (when they would be passed to
   gss_verify or gss_unseal).  Occasionally, tokens may be received at
   other times, and gss_process_context_token allows such tokens to be
   passed to the underlying security service for processing.  At
   present, such additional tokens may only be generated by
   gss_delete_sec_context.  GSSAPI implementation may use this service
   to implement deletion of the security context.

   Parameters:

      context_handle    gss_ctx_id_t, read
                        context handle of context on which token is to
                        be processed

      token_buffer      buffer, opaque, read
                        pointer to first byte of token to process

      minor_status      integer, modify
                        Implementation specific status code.

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_DEFECTIVE_TOKEN Indicates that consistency checks
                        performed on the token failed

      GSS_S_FAILURE     Failure.  See minor_status for more information

      GSS_S_NO_CONTEXT The context_handle did not refer to a valid
                       context

3.6. gss_delete_sec_context

      OM_uint32  gss_delete_sec_context (
                     OM_uint32 *     minor_status,
                     gss_ctx_id_t *  context_handle,
                     gss_buffer_t    output_token)

   Purpose:

   Delete a security context.  gss_delete_sec_context will delete the
   local data structures associated with the specified security context,
   and generate an output_token, which when passed to the peer
   gss_process_context_token will instruct it to do likewise.  No
   further security services may be obtained using the context specified
   by context_handle.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code.

      context_handle    gss_ctx_id_t, modify
                        context handle identifying context to delete.

      output_token      buffer, opaque, modify
                        token to be sent to remote application to
                        instruct it to also delete the context

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_FAILURE     Failure, see minor_status for more information

      GSS_S_NO_CONTEXT  No valid context was supplied

3.7. gss_context_time

      OM_uint32  gss_context_time (
                     OM_uint32 *     minor_status,
                     gss_ctx_id_t    context_handle,
                     OM_uint32 *     time_rec)
   Purpose:

   Determines the number of seconds for which the specified context will
   remain valid.

      Parameters:

      minor_status      integer, modify
                        Implementation specific status code.

      context_handle    gss_ctx_id_t, read
                        Identifies the context to be interrogated.

      time_rec          integer, modify
                        Number of seconds that the context will remain
                        valid.  If the context has already expired,
                        zero will be returned.
   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_CONTEXT_EXPIRED The context has already expired

      GSS_S_CREDENTIALS_EXPIRED The context is recognized, but
                        associated credentials have expired

      GSS_S_NO_CONTEXT The context_handle parameter did not identify a
                        valid context

3.8. gss_sign

      OM_uint32  gss_sign (
                     OM_uint32 *     minor_status,
                     gss_ctx_id_t    context_handle,
                     int             qop_req,
                     gss_buffer_t    message_buffer,
                     gss_buffer_t    msg_token)
   Purpose:

   Generates a cryptographic signature for the supplied message, and
   places the signature in a token for transfer to the peer application.
   The qop_req parameter allows a choice between several cryptographic
   algorithms, if supported by the chosen mechanism.

   Parameters:

      minor_status      integer, modify
                        Implementation specific status code.

      context_handle    gss_ctx_id_t, read
                        identifies the context on which the message

                        will be sent

      qop_req           integer, read, optional
                        Specifies requested quality of protection.
                        Callers are encouraged, on portability grounds,
                        to accept the default quality of protection
                        offered by the chosen mechanism, which may be
                        requested by specifying GSS_C_QOP_DEFAULT for
                        this parameter.  If an unsupported protection
                        strength is requested, gss_sign will return a
                        major_status of GSS_S_FAILURE.

      message_buffer    buffer, opaque, read
                        message to be signed

      msg_token         buffer, opaque, modify
                        buffer to receive token

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_CONTEXT_EXPIRED The context has already expired

      GSS_S_CREDENTIALS_EXPIRED The context is recognized, but
                        associated credentials have expired

      GSS_S_NO_CONTEXT  The context_handle parameter did not identify a
                        valid context

      GSS_S_FAILURE     Failure. See minor_status for more information.

3.9. gss_verify

      OM_uint32  gss_verify (
                     OM_uint32 *     minor_status,
                     gss_ctx_id_t    context_handle,
                     gss_buffer_t    message_buffer,
                     gss_buffer_t    token_buffer,
                     int *           qop_state)
   Purpose:

   Verifies that a cryptographic signature, contained in the token
   parameter, fits the supplied message.  The qop_state parameter allows
   a message recipient to determine the strength of protection that was
   applied to the message.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code.

      context_handle    gss_ctx_id_t, read
                        identifies the context on which the message
                        arrived

      message_buffer    buffer, opaque, read
                        message to be verified

      token_buffer      buffer, opaque, read
                        token associated with message

      qop_state         integer, modify
                        quality of protection gained from signature

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_DEFECTIVE_TOKEN The token failed consistency checks

      GSS_S_BAD_SIG     The signature was incorrect

      GSS_S_DUPLICATE_TOKEN The token was valid, and contained a correct
                        signature for the message, but it had already
                        been processed

      GSS_S_OLD_TOKEN   The token was valid, and contained a correct
                        signature for the message, but it is too old

      GSS_S_UNSEQ_TOKEN The token was valid, and contained a correct
                        signature for the message, but has been
                        verified out of sequence; an earlier token has
                        been signed or sealed by the remote
                        application, but not yet been processed
                        locally.

      GSS_S_CONTEXT_EXPIRED The context has already expired

      GSS_S_CREDENTIALS_EXPIRED The context is recognized, but
                        associated credentials have expired

      GSS_S_NO_CONTEXT  The context_handle parameter did not identify a
                        valid context

      GSS_S_FAILURE     Failure.  See minor_status for more information.

3.10. gss_seal

      OM_uint32  gss_seal (
                     OM_uint32 *     minor_status,
                     gss_ctx_id_t    context_handle,
                     int             conf_req_flag,
                     int             qop_req
                     gss_buffer_t    input_message_buffer,
                     int *           conf_state,
                     gss_buffer_t    output_message_buffer)

   Purpose:

   Cryptographically signs and optionally encrypts the specified
   input_message.  The output_message contains both the signature and
   the message.  The qop_req parameter allows a choice between several
   cryptographic algorithms, if supported by the chosen mechanism.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code.

      context_handle    gss_ctx_id_t, read
                        identifies the context on which the message
                        will be sent

      conf_req_flag     boolean, read
                        True - Both confidentiality and integrity
                               services are requested
                        False - Only integrity service is requested

      qop_req           integer, read, optional
                        Specifies required quality of protection.  A
                        mechanism-specific default may be requested by
                        setting qop_req to GSS_C_QOP_DEFAULT.  If an
                        unsupported protection strength is requested,
                        gss_seal will return a major_status of
                        GSS_S_FAILURE.

      input_message_buffer   buffer, opaque, read
                             message to be sealed

      conf_state        boolean, modify
                        True - Confidentiality, data origin
                               authentication and integrity services
                               have been applied
                        False - Integrity and data origin services only
                                has been applied.

      output_message_buffer  buffer, opaque, modify
                             buffer to receive sealed message

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_CONTEXT_EXPIRED The context has already expired

      GSS_S_CREDENTIALS_EXPIRED The context is recognized, but
                        associated credentials have expired

      GSS_S_NO_CONTEXT  The context_handle parameter did not identify a
                        valid context

      GSS_S_FAILURE     Failure.  See minor_status for more information.

3.11. gss_unseal

      OM_uint32  gss_unseal (
                     OM_uint32 *     minor_status,
                     gss_ctx_id_t    context_handle,
                     gss_buffer_t    input_message_buffer,
                     gss_buffer_t    output_message_buffer,
                     int *           conf_state,
                     int *           qop_state)

   Purpose:

   Converts a previously sealed message back to a usable form, verifying
   the embedded signature.  The conf_state parameter indicates whether
   the message was encrypted; the qop_state parameter indicates the
   strength of protection that was used to provide the confidentiality
   and integrity services.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code.

      context_handle    gss_ctx_id_t, read
                        identifies the context on which the message
                        arrived

      input_message_buffer   buffer, opaque, read
                             sealed message

      output_message_buffer  buffer, opaque, modify
                             buffer to receive unsealed message

      conf_state        boolean, modify
                        True - Confidentiality and integrity protection
                               were used
                        False - Inteegrity service only was used

      qop_state         integer, modify
                        quality of protection gained from signature

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_DEFECTIVE_TOKEN The token failed consistency checks

      GSS_S_BAD_SIG     The signature was incorrect

      GSS_S_DUPLICATE_TOKEN The token was valid, and contained a
                        correct signature for the message, but it had
                        already been processed

      GSS_S_OLD_TOKEN The token was valid, and contained a correct
                        signature for the message, but it is too old

      GSS_S_UNSEQ_TOKEN The token was valid, and contained a correct
                        signature for the message, but has been
                        verified out of sequence; an earlier token has
                        been signed or sealed by the remote
                        application, but not yet been processed
                        locally.

      GSS_S_CONTEXT_EXPIRED The context has already expired

      GSS_S_CREDENTIALS_EXPIRED The context is recognized, but
                        associated credentials have expired

      GSS_S_NO_CONTEXT  The context_handle parameter did not identify a
                        valid context

      GSS_S_FAILURE     Failure.  See minor_status for more information.

3.12. gss_display_status

      OM_uint32  gss_display_status (
                     OM_uint32 *     minor_status,
                     int             status_value,
                     int             status_type,
                     gss_OID         mech_type,
                     int *           message_context,
                     gss_buffer_t    status_string)

   Purpose:

   Allows an application to obtain a textual representation of a GSSAPI
   status code, for display to the user or for logging purposes.  Since
   some status values may indicate multiple errors, applications may
   need to call gss_display_status multiple times, each call generating
   a single text string.  The message_context parameter is used to
   indicate which error message should be extracted from a given
   status_value; message_context should be initialized to 0, and
   gss_display_status will return a non-zero value if there are further
   messages to extract.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code.

      status_value      integer, read
                        Status value to be converted

      status_type       integer, read
                        GSS_C_GSS_CODE - status_value is a GSS status
                                         code
                        GSS_C_MECH_CODE - status_value is a mechanism
                                          status code

      mech_type         Object ID, read, optional
                        Underlying mechanism (used to interpret a
                        minor status value) Supply GSS_C_NULL_OID to
                        obtain the system default.

      message_context   integer, read/modify
                        Should be initialized to zero by caller

                        on first call.  If further messages are
                        contained in the status_value parameter,
                        message_context will be non-zero on return,
                        and this value should be passed back to
                        subsequent calls, along with the same
                        status_value, status_type and mech_type
                        parameters.

      status_string     buffer, character string, modify
                        textual interpretation of the status_value

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_BAD_MECH    Indicates that translation in accordance with
                        an unsupported mechanism type was requested

      GSS_S_BAD_STATUS The status value was not recognized, or the
                        status type was neither GSS_C_GSS_CODE nor
                        GSS_C_MECH_CODE.

3.13. gss_indicate_mechs

      OM_uint32  gss_indicate_mechs (
                     OM_uint32 *     minor_status,
                     gss_OID_set *   mech_set)

   Purpose:

         Allows an application to determine which underlying security
         mechanisms are available.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code.

      mech_set          set of Object IDs, modify
                        set of implementation-supported mechanisms.
                        The returned gss_OID_set value will be a
                        pointer into static storage, and should be
                        treated as read-only by the caller.

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

3.14. gss_compare_name

      OM_uint32  gss_compare_name (
                     OM_uint32 *     minor_status,
                     gss_name_t      name1,
                     gss_name_t      name2,
                     int *           name_equal)

   Purpose:

   Allows an application to compare two internal-form names to determine
   whether they refer to the same entity.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code.

      name1             gss_name_t, read
                        internal-form  name

      name2             gss_name_t, read
                        internal-form  name

      name_equal        boolean, modify
                        True - names refer to same entity
                        False - names refer to different entities
                                (strictly, the names are not known to
                                refer to the same identity).
   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_BAD_NAMETYPE The type contained within either name1 or
                        name2 was unrecognized, or the names were of
                        incomparable types.

      GSS_S_BAD_NAME    One or both of name1 or name2 was ill-formed

3.15. gss_display_name

      OM_uint32  gss_display_name (
                     OM_uint32 *     minor_status,
                     gss_name_t      input_name,
                     gss_buffer_t    output_name_buffer,
                     gss_OID *       output_name_type)

   Purpose:

   Allows an application to obtain a textual representation of an opaque
   internal-form  name for display purposes.  The syntax of a printable
   name is defined by the GSSAPI implementation.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code.

      input_name        gss_name_t, read
                        name to be displayed

      output_name_buffer   buffer, character-string, modify
                           buffer to receive textual name string

      output_name_type  Object ID, modify
                        The type of the returned name.  The returned
                        gss_OID will be a pointer into static storage,
                        and should be treated as read-only by the caller

   Function value:

      GSS status code:

      GSS_S_COMPLETE    Successful completion

      GSS_S_BAD_NAMETYPE The type of input_name was not recognized

      GSS_S_BAD_NAME    input_name was ill-formed

3.16. gss_import_name

      OM_uint32 gss_import_name (
                    OM_uint32 *     minor_status,
                    gss_buffer_t    input_name_buffer,
                    gss_OID         input_name_type,
                    gss_name_t *    output_name)

   Purpose:

   Convert a printable name to internal form.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code

      input_name_buffer    buffer, character-string, read
                           buffer containing printable name to convert

      input_name_type   Object ID, read, optional
                        Object Id specifying type of printable
                        name.  Applications may specify either
                        GSS_C_NULL_OID to use a local system-specific
                        printable syntax, or an OID registered by the
                        GSSAPI implementation to name a particular
                        namespace.

      output_name       gss_name_t, modify
                        returned name in internal form

   Function value:

      GSS status code

      GSS_S_COMPLETE    Successful completion

      GSS_S_BAD_NAMETYPE The input_name_type was unrecognized

      GSS_S_BAD_NAME    The input_name parameter could not be
                        interpreted as a name of the specified type

3.17. gss_release_name

      OM_uint32 gss_release_name (
                    OM_uint32 *     minor_status,
                    gss_name_t *    name)

   Purpose:

   Free GSSAPI-allocated storage associated with an internal form name.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code

      name              gss_name_t, modify
                        The name to be deleted

   Function value:

      GSS status code

      GSS_S_COMPLETE    Successful completion

      GSS_S_BAD_NAME    The name parameter did not contain a valid name

3.18. gss_release_buffer

      OM_uint32 gss_release_buffer (
                    OM_uint32 *     minor_status,
                    gss_buffer_t    buffer)

   Purpose:

   Free storage associated with a buffer format name.  The storage must
   have been allocated by a GSSAPI routine.  In addition to freeing the
   associated storage, the routine will zero the length field in the
   buffer parameter.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code

      buffer            buffer, modify
                        The storage associated with the buffer will be
                        deleted.  The gss_buffer_desc object will not
                        be freed, but its length field will be zeroed.

   Function value:

      GSS status code

      GSS_S_COMPLETE    Successful completion

3.19. gss_release_oid_set

      OM_uint32 gss_release_oid_set (
                    OM_uint32 *     minor_status,
                    gss_OID_set *   set)

   Purpose:

   Free storage associated with a gss_OID_set object.  The storage must
   have been allocated by a GSSAPI routine.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code

      set               Set of Object IDs, modify
                        The storage associated with the gss_OID_set
                        will be deleted.

   Function value:

      GSS status code

      GSS_S_COMPLETE    Successful completion

3.20. gss_inquire_cred

      OM_uint32 gss_inquire_cred (
                    OM_uint32  *    minor_status,
                    gss_cred_id_t   cred_handle,
                    gss_name_t *    name,
                    OM_uint32 *     lifetime,
                    int *           cred_usage,
                    gss_OID_set *   mechanisms )

   Purpose:

   Obtains information about a credential.  The caller must already have
   obtained a handle that refers to the credential.

   Parameters:

      minor_status      integer, modify
                        Mechanism specific status code

      cred_handle       gss_cred_id_t, read
                        A handle that refers to the target credential.
                        Specify GSS_C_NO_CREDENTIAL to inquire about
                        the default credential.

      name              gss_name_t, modify
                        The name whose identity the credential asserts.
                        Specify NULL if not required.

      lifetime          Integer, modify

                        The number of seconds for which the credential
                        will remain valid.  If the credential has
                        expired, this parameter will be set to zero.
                        If the implementation does not support
                        credential expiration, the value
                        GSS_C_INDEFINITE will be returned.  Specify
                        NULL if not required.

      cred_usage        Integer, modify
                        How the credential may be used.  One of the
                        following:
                           GSS_C_INITIATE
                           GSS_C_ACCEPT
                           GSS_C_BOTH
                        Specify NULL if not required.

      mechanisms        gss_OID_set, modify
                        Set of mechanisms supported by the credential.
                        Specify NULL if not required.

   Function value:

      GSS status code

      GSS_S_COMPLETE    Successful completion

      GSS_S_NO_CRED     The referenced credentials could not be
                        accessed.

      GSS_S_DEFECTIVE_CREDENTIAL The referenced credentials were
                        invalid.

      GSS_S_CREDENTIALS_EXPIRED The referenced credentials have expired.
                        If the lifetime parameter was not passed as
                        NULL, it will be set to 0.

  #ifndef GSSAPI_H_
  #define GSSAPI_H_

  /*
   * First, define the platform-dependent types.
   */
  typedef <platform-specific> OM_uint32;
  typedef <platform-specific> gss_ctx_id_t;
  typedef <platform-specific> gss_cred_id_t;
  typedef <platform-specific> gss_name_t;

  /*
   * Note that a platform supporting the xom.h X/Open header file
   * may make use of that header for the definitions of OM_uint32
   * and the structure to which gss_OID_desc equates.
   */

  typedef struct gss_OID_desc_struct {
        OM_uint32 length;
        void      *elements;
  } gss_OID_desc, *gss_OID;

  typedef struct gss_OID_set_desc_struct  {
        int     count;
        gss_OID elements;
  } gss_OID_set_desc, *gss_OID_set;

  typedef struct gss_buffer_desc_struct {
        size_t length;
        void *value;
  } gss_buffer_desc, *gss_buffer_t;

  typedef struct gss_channel_bindings_struct {
        OM_uint32 initiator_addrtype;
        gss_buffer_desc initiator_address;
        OM_uint32 acceptor_addrtype;
        gss_buffer_desc acceptor_address;
        gss_buffer_desc application_data;
  } *gss_channel_bindings_t;

  /*
   * Six independent flags each of which indicates that a context
   * supports a specific service option.
   */
  #define GSS_C_DELEG_FLAG 1
  #define GSS_C_MUTUAL_FLAG 2
  #define GSS_C_REPLAY_FLAG 4
  #define GSS_C_SEQUENCE_FLAG 8
  #define GSS_C_CONF_FLAG 16
  #define GSS_C_INTEG_FLAG 32

  /*
   * Credential usage options
   */
  #define GSS_C_BOTH 0
  #define GSS_C_INITIATE 1
  #define GSS_C_ACCEPT 2

  /*
   * Status code types for gss_display_status
   */
  #define GSS_C_GSS_CODE 1
  #define GSS_C_MECH_CODE 2

  /*
   * The constant definitions for channel-bindings address families
   */
  #define GSS_C_AF_UNSPEC     0;
  #define GSS_C_AF_LOCAL      1;
  #define GSS_C_AF_INET       2;
  #define GSS_C_AF_IMPLINK    3;
  #define GSS_C_AF_PUP        4;
  #define GSS_C_AF_CHAOS      5;
  #define GSS_C_AF_NS         6;
  #define GSS_C_AF_NBS        7;
  #define GSS_C_AF_ECMA       8;
  #define GSS_C_AF_DATAKIT    9;
  #define GSS_C_AF_CCITT      10;
  #define GSS_C_AF_SNA        11;
  #define GSS_C_AF_DECnet     12;
  #define GSS_C_AF_DLI        13;
  #define GSS_C_AF_LAT        14;
  #define GSS_C_AF_HYLINK     15;
  #define GSS_C_AF_APPLETALK  16;
  #define GSS_C_AF_BSC        17;
  #define GSS_C_AF_DSS        18;
  #define GSS_C_AF_OSI        19;
  #define GSS_C_AF_X25        21;

  #define GSS_C_AF_NULLADDR   255;

  #define GSS_C_NO_BUFFER ((gss_buffer_t) 0)
  #define GSS_C_NULL_OID ((gss_OID) 0)
  #define GSS_C_NULL_OID_SET ((gss_OID_set) 0)
  #define GSS_C_NO_CONTEXT ((gss_ctx_id_t) 0)
  #define GSS_C_NO_CREDENTIAL ((gss_cred_id_t) 0)
  #define GSS_C_NO_CHANNEL_BINDINGS ((gss_channel_bindings_t) 0)
  #define GSS_C_EMPTY_BUFFER {0, NULL}

  /*
   * Define the default Quality of Protection for per-message
   * services.  Note that an implementation that offers multiple
   * levels of QOP may either reserve a value (for example zero,
   * as assumed here) to mean "default protection", or alternatively
   * may simply equate GSS_C_QOP_DEFAULT to a specific explicit QOP
   * value.

   */
  #define GSS_C_QOP_DEFAULT 0

  /*
   * Expiration time of 2^32-1 seconds means infinite lifetime for a
   * credential or security context
   */
  #define GSS_C_INDEFINITE 0xfffffffful

  /* Major status codes */

  #define GSS_S_COMPLETE 0

  /*
   * Some "helper" definitions to make the status code macros obvious.
   */
  #define GSS_C_CALLING_ERROR_OFFSET 24
  #define GSS_C_ROUTINE_ERROR_OFFSET 16
  #define GSS_C_SUPPLEMENTARY_OFFSET 0
  #define GSS_C_CALLING_ERROR_MASK 0377ul
  #define GSS_C_ROUTINE_ERROR_MASK 0377ul
  #define GSS_C_SUPPLEMENTARY_MASK 0177777ul

  /*
   * The macros that test status codes for error conditions
   */
  #define GSS_CALLING_ERROR(x) \
    (x & (GSS_C_CALLING_ERROR_MASK << GSS_C_CALLING_ERROR_OFFSET))
  #define GSS_ROUTINE_ERROR(x) \
    (x & (GSS_C_ROUTINE_ERROR_MASK << GSS_C_ROUTINE_ERROR_OFFSET))
  #define GSS_SUPPLEMENTARY_INFO(x) \
    (x & (GSS_C_SUPPLEMENTARY_MASK << GSS_C_SUPPLEMENTARY_OFFSET))
  #define GSS_ERROR(x) \
    ((GSS_CALLING_ERROR(x) != 0) || (GSS_ROUTINE_ERROR(x) != 0))

  /*
   * Now the actual status code definitions
   */

  /*
   * Calling errors:
   */
  #define GSS_S_CALL_INACCESSIBLE_READ \
                               (1ul << GSS_C_CALLING_ERROR_OFFSET)
  #define GSS_S_CALL_INACCESSIBLE_WRITE \
                               (2ul << GSS_C_CALLING_ERROR_OFFSET)

  #define GSS_S_CALL_BAD_STRUCTURE \
                               (3ul << GSS_C_CALLING_ERROR_OFFSET)

  /*
   * Routine errors:
   */
  #define GSS_S_BAD_MECH (1ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_BAD_NAME (2ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_BAD_NAMETYPE (3ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_BAD_BINDINGS (4ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_BAD_STATUS (5ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_BAD_SIG (6ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_NO_CRED (7ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_NO_CONTEXT (8ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_DEFECTIVE_TOKEN (9ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_DEFECTIVE_CREDENTIAL (10ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_CREDENTIALS_EXPIRED (11ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_CONTEXT_EXPIRED (12ul << GSS_C_ROUTINE_ERROR_OFFSET)
  #define GSS_S_FAILURE (13ul << GSS_C_ROUTINE_ERROR_OFFSET)

  /*
   * Supplementary info bits:
   */
  #define GSS_S_CONTINUE_NEEDED (1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 0))
  #define GSS_S_DUPLICATE_TOKEN (1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 1))
  #define GSS_S_OLD_TOKEN (1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 2))
  #define GSS_S_UNSEQ_TOKEN (1ul << (GSS_C_SUPPLEMENTARY_OFFSET + 3))

  /*
   * Finally, function prototypes for the GSSAPI routines.
   */

  OM_uint32 gss_acquire_cred
             (OM_uint32*,       /* minor_status */
              gss_name_t,       /* desired_name */
              OM_uint32,        /* time_req */
              gss_OID_set,      /* desired_mechs */
              int,              /* cred_usage */
              gss_cred_id_t*,   /* output_cred_handle */
              gss_OID_set*,     /* actual_mechs */
              OM_uint32*        /* time_rec */
             );

  OM_uint32 gss_release_cred,
             (OM_uint32*,       /* minor_status */
              gss_cred_id_t*    /* cred_handle */
             );

  OM_uint32 gss_init_sec_context
             (OM_uint32*,       /* minor_status */
              gss_cred_id_t,    /* claimant_cred_handle */
              gss_ctx_id_t*,    /* context_handle */
              gss_name_t,       /* target_name */
              gss_OID,          /* mech_type */
              int,              /* req_flags */
              OM_uint32,        /* time_req */
              gss_channel_bindings_t,
                                /* input_chan_bindings */
              gss_buffer_t,     /* input_token */
              gss_OID*,         /* actual_mech_type */
              gss_buffer_t,     /* output_token */
              int*,             /* ret_flags */
              OM_uint32*        /* time_rec */
             );

  OM_uint32 gss_accept_sec_context
             (OM_uint32*,       /* minor_status */
              gss_ctx_id_t*,    /* context_handle */
              gss_cred_id_t,    /* verifier_cred_handle */
              gss_buffer_t,     /* input_token_buffer */
              gss_channel_bindings_t,
                                /* input_chan_bindings */
              gss_name_t*,      /* src_name */
              gss_OID*,         /* mech_type */
              gss_buffer_t,     /* output_token */
              int*,             /* ret_flags */
              OM_uint32*,       /* time_rec */
              gss_cred_id_t*    /* delegated_cred_handle */
             );

  OM_uint32 gss_process_context_token
             (OM_uint32*,       /* minor_status */
              gss_ctx_id_t,     /* context_handle */
              gss_buffer_t      /* token_buffer */
             );

  OM_uint32 gss_delete_sec_context
             (OM_uint32*,       /* minor_status */
              gss_ctx_id_t*,    /* context_handle */
              gss_buffer_t      /* output_token */
             );

  OM_uint32 gss_context_time
             (OM_uint32*,       /* minor_status */
              gss_ctx_id_t,     /* context_handle */
              OM_uint32*        /* time_rec */
             );

  OM_uint32 gss_sign
             (OM_uint32*,       /* minor_status */
              gss_ctx_id_t,     /* context_handle */
              int,              /* qop_req */
              gss_buffer_t,     /* message_buffer */
              gss_buffer_t      /* message_token */
             );

  OM_uitn32 gss_verify
             (OM_uint32*,       /* minor_status */
              gss_ctx_id_t,     /* context_handle */
              gss_buffer_t,     /* message_buffer */
              gss_buffer_t,     /* token_buffer */
              int*              /* qop_state */
             );

  OM_uint32 gss_seal
             (OM_uint32*,       /* minor_status */
              gss_ctx_id_t,     /* context_handle */
              int,              /* conf_req_flag */
              int,              /* qop_req */
              gss_buffer_t,     /* input_message_buffer */
              int*,             /* conf_state */
              gss_buffer_t      /* output_message_buffer */
             );

  OM_uint32 gss_unseal
             (OM_uint32*,       /* minor_status */
              gss_ctx_id_t,     /* context_handle */
              gss_buffer_t,     /* input_message_buffer */
              gss_buffer_t,     /* output_message_buffer */
              int*,             /* conf_state */
              int*              /* qop_state */
             );

  OM_uint32 gss_display_status
             (OM_uint32*,       /* minor_status */
              OM_uint32,        /* status_value */
              int,              /* status_type */
              gss_OID,          /* mech_type */
              int*,             /* message_context */
              gss_buffer_t      /* status_string */
             );

  OM_uint32 gss_indicate_mechs
             (OM_uint32*,       /* minor_status */
              gss_OID_set*      /* mech_set */
             );

  OM_uint32 gss_compare_name
             (OM_uint32*,       /* minor_status */
              gss_name_t,       /* name1 */
              gss_name_t,       /* name2 */
              int*              /* name_equal */
             );

  OM_uint32 gss_display_name,
             (OM_uint32*,      /* minor_status */
              gss_name_t,      /* input_name */
              gss_buffer_t,     /* output_name_buffer */
              gss_OID*         /* output_name_type */
             );

  OM_uint32 gss_import_name
             (OM_uint32*,       /* minor_status */
              gss_buffer_t,     /* input_name_buffer */
              gss_OID,          /* input_name_type */
              gss_name_t*       /* output_name */
             );

  OM_uint32 gss_release_name
             (OM_uint32*,       /* minor_status */
              gss_name_t*       /* input_name */
             );

  OM_uint32 gss_release_buffer
             (OM_uint32*,       /* minor_status */
              gss_buffer_t      /* buffer */
             );

  OM_uint32 gss_release_oid_set
             (OM_uint32*,       /* minor_status */
              gss_OID_set*      /* set */

             );

  OM_uint32 gss_inquire_cred
             (OM_uint32 *,      /* minor_status */
              gss_cred_id_t,    /* cred_handle */
              gss_name_t *,     /* name */
              OM_uint32 *,      /* lifetime */
              int *,            /* cred_usage */
              gss_OID_set *     /* mechanisms */
             );

  #endif /* GSSAPI_H_ */

References

   [1] Linn, J., "Generic Security Service Application Program
       Interface", RFC 1508, Geer Zolot Associate, September 1993.

   [2] "OSI Object Management API Specification, Version 2.0 t", X.400
       API Association & X/Open Company Limited, August 24, 1990.
       Specification of datatypes and routines for manipulating
       information objects.

Security Considerations

   Security issues are discussed throughout this memo.

Author's Address

   John Wray
   Digital Equipment Corporation
   550 King Street, LKG2-2/AA6
   Littleton, MA  01460
   USA

   Phone: +1-508-486-5210
   EMail: Wray@tuxedo.enet.dec.com

 

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