File: rfc2078.txt

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Network Working Group                                           J. Linn
Request for Comments: 2078                      OpenVision Technologies
Category: Standards Track                                  January 1997
Obsoletes: 1508


   Generic Security Service Application Program Interface, Version 2

Status of this Memo

   This document 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" (STD 1) for the standardization state
   and status of this protocol.  Distribution of this memo is unlimited.

Abstract

   The Generic Security Service Application Program Interface (GSS-API),
   as defined in RFC-1508, provides security services to callers in a
   generic fashion, supportable with a range of underlying mechanisms
   and technologies and hence allowing source-level portability of
   applications to different environments. This specification defines
   GSS-API services and primitives at a level independent of underlying
   mechanism and programming language environment, and is to be
   complemented by other, related specifications:

      documents defining specific parameter bindings for particular
      language environments

      documents defining token formats, protocols, and procedures to be
      implemented in order to realize GSS-API services atop particular
      security mechanisms

   This memo revises RFC-1508, making specific, incremental changes in
   response to implementation experience and liaison requests. It is
   intended, therefore, that this memo or a successor version thereto
   will become the basis for subsequent progression of the GSS-API
   specification on the standards track.

Table of Contents

   1: GSS-API Characteristics and Concepts..........................  3
   1.1: GSS-API Constructs..........................................  6
   1.1.1:  Credentials..............................................  6
   1.1.1.1: Credential Constructs and Concepts......................  6
   1.1.1.2: Credential Management...................................  7
   1.1.1.3: Default Credential Resolution...........................  8



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RFC 2078                        GSS-API                     January 1997


   1.1.2: Tokens....................................................  9
   1.1.3:  Security Contexts........................................ 10
   1.1.4:  Mechanism Types.......................................... 11
   1.1.5:  Naming................................................... 12
   1.1.6:  Channel Bindings......................................... 14
   1.2:  GSS-API Features and Issues................................ 15
   1.2.1:  Status Reporting......................................... 15
   1.2.2: Per-Message Security Service Availability................. 17
   1.2.3: Per-Message Replay Detection and Sequencing............... 18
   1.2.4:  Quality of Protection.................................... 20
   1.2.5: Anonymity Support......................................... 21
   1.2.6: Initialization............................................ 22
   1.2.7: Per-Message Protection During Context Establishment....... 22
   1.2.8: Implementation Robustness................................. 23
   2:  Interface Descriptions....................................... 23
   2.1:  Credential management calls................................ 25
   2.1.1:  GSS_Acquire_cred call.................................... 26
   2.1.2:  GSS_Release_cred call.................................... 28
   2.1.3:  GSS_Inquire_cred call.................................... 29
   2.1.4:  GSS_Add_cred call........................................ 31
   2.1.5:  GSS_Inquire_cred_by_mech call............................ 33
   2.2:  Context-level calls........................................ 34
   2.2.1:  GSS_Init_sec_context call................................ 34
   2.2.2:  GSS_Accept_sec_context call.............................. 40
   2.2.3:  GSS_Delete_sec_context call.............................. 44
   2.2.4:  GSS_Process_context_token call........................... 46
   2.2.5:  GSS_Context_time call.................................... 47
   2.2.6:  GSS_Inquire_context call................................. 47
   2.2.7:  GSS_Wrap_size_limit call................................. 49
   2.2.8:  GSS_Export_sec_context call.............................. 50
   2.2.9:  GSS_Import_sec_context call.............................. 52
   2.3:  Per-message calls.......................................... 53
   2.3.1:  GSS_GetMIC call.......................................... 54
   2.3.2:  GSS_VerifyMIC call....................................... 55
   2.3.3:  GSS_Wrap call............................................ 56
   2.3.4:  GSS_Unwrap call.......................................... 58
   2.4:  Support calls.............................................. 59
   2.4.1:  GSS_Display_status call.................................. 60
   2.4.2:  GSS_Indicate_mechs call.................................. 60
   2.4.3:  GSS_Compare_name call.................................... 61
   2.4.4:  GSS_Display_name call.................................... 62
   2.4.5:  GSS_Import_name call..................................... 63
   2.4.6:  GSS_Release_name call.................................... 64
   2.4.7:  GSS_Release_buffer call.................................. 65
   2.4.8:  GSS_Release_OID_set call................................. 65
   2.4.9:  GSS_Create_empty_OID_set call............................ 66
   2.4.10: GSS_Add_OID_set_member call.............................. 67
   2.4.11: GSS_Test_OID_set_member call............................. 67



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   2.4.12: GSS_Release_OID call..................................... 68
   2.4.13: GSS_OID_to_str call...................................... 68
   2.4.14: GSS_Str_to_OID call...................................... 69
   2.4.15: GSS_Inquire_names_for_mech call.......................... 69
   2.4.16: GSS_Inquire_mechs_for_name call.......................... 70
   2.4.17: GSS_Canonicalize_name call............................... 71
   2.4.18: GSS_Export_name call..................................... 72
   2.4.19: GSS_Duplicate_name call.................................. 73
   3: Data Structure Definitions for GSS-V2 Usage................... 73
   3.1: Mechanism-Independent Token Format.......................... 74
   3.2: Mechanism-Independent Exported Name Object Format........... 77
   4: Name Type Definitions......................................... 77
   4.1: Host-Based Service Name Form................................ 77
   4.2: User Name Form.............................................. 78
   4.3: Machine UID Form............................................ 78
   4.4: String UID Form............................................. 79
   5:  Mechanism-Specific Example Scenarios......................... 79
   5.1: Kerberos V5, single-TGT..................................... 79
   5.2: Kerberos V5, double-TGT..................................... 80
   5.3:  X.509 Authentication Framework............................. 81
   6:  Security Considerations...................................... 82
   7:  Related Activities........................................... 82
   Appendix A: Mechanism Design Constraints......................... 83
   Appendix B: Compatibility with GSS-V1............................ 83

1: GSS-API Characteristics and Concepts

   GSS-API operates in the following paradigm.  A typical GSS-API caller
   is itself a communications protocol, calling on GSS-API in order to
   protect its communications with authentication, integrity, and/or
   confidentiality security services.  A GSS-API caller accepts tokens
   provided to it by its local GSS-API implementation and transfers the
   tokens to a peer on a remote system; that peer passes the received
   tokens to its local GSS-API implementation for processing. The
   security services available through GSS-API in this fashion are
   implementable (and have been implemented) over a range of underlying
   mechanisms based on secret-key and public-key cryptographic
   technologies.

   The GSS-API separates the operations of initializing a security
   context between peers, achieving peer entity authentication (This
   security service definition, and other definitions used in this
   document, corresponds to that provided in International Standard ISO
   7498-2-1988(E), Security Architecture.) (GSS_Init_sec_context()  and
   GSS_Accept_sec_context() calls), from the operations of providing
   per-message data origin authentication and data integrity protection
   (GSS_GetMIC()  and GSS_VerifyMIC()  calls) for messages subsequently
   transferred in conjunction with that context.  When establishing a



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   security context, the GSS-API enables a context initiator to
   optionally permit its credentials to be delegated, meaning that the
   context acceptor may initiate further security contexts on behalf of
   the initiating caller. Per-message GSS_Wrap()  and GSS_Unwrap() calls
   provide the data origin authentication and data integrity services
   which GSS_GetMIC()  and GSS_VerifyMIC() offer, and also support
   selection of confidentiality services as a caller option.  Additional
   calls provide supportive functions to the GSS-API's users.

   The following paragraphs provide an example illustrating the
   dataflows involved in use of the GSS-API by a client and server in a
   mechanism-independent fashion, establishing a security context and
   transferring a protected message. The example assumes that credential
   acquisition has already been completed.  The example assumes that the
   underlying authentication technology is capable of authenticating a
   client to a server using elements carried within a single token, and
   of authenticating the server to the client (mutual authentication)
   with a single returned token; this assumption holds for presently-
   documented CAT mechanisms but is not necessarily true for other
   cryptographic technologies and associated protocols.

   The client calls GSS_Init_sec_context()  to establish a security
   context to the server identified by targ_name, and elects to set the
   mutual_req_flag so that mutual authentication is performed in the
   course of context establishment. GSS_Init_sec_context()  returns an
   output_token to be passed to the server, and indicates
   GSS_S_CONTINUE_NEEDED status pending completion of the mutual
   authentication sequence. Had mutual_req_flag not been set, the
   initial call to GSS_Init_sec_context()  would have returned
   GSS_S_COMPLETE status. The client sends the output_token to the
   server.

   The server passes the received token as the input_token parameter to
   GSS_Accept_sec_context().  GSS_Accept_sec_context indicates
   GSS_S_COMPLETE status, provides the client's authenticated identity
   in the src_name result, and provides an output_token to be passed to
   the client. The server sends the output_token to the client.

   The client passes the received token as the input_token parameter to
   a successor call to GSS_Init_sec_context(),  which processes data
   included in the token in order to achieve mutual authentication from
   the client's viewpoint. This call to GSS_Init_sec_context()  returns
   GSS_S_COMPLETE status, indicating successful mutual authentication
   and the completion of context establishment for this example.

   The client generates a data message and passes it to GSS_Wrap().
   GSS_Wrap() performs data origin authentication, data integrity, and
   (optionally) confidentiality processing on the message and



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   encapsulates the result into output_message, indicating
   GSS_S_COMPLETE status. The client sends the output_message to the
   server.

   The server passes the received message to GSS_Unwrap().  GSS_Unwrap()
   inverts the encapsulation performed by GSS_Wrap(),  deciphers the
   message if the optional confidentiality feature was applied, and
   validates the data origin authentication and data integrity checking
   quantities. GSS_Unwrap()  indicates successful validation by
   returning GSS_S_COMPLETE status along with the resultant
   output_message.

   For purposes of this example, we assume that the server knows by
   out-of-band means that this context will have no further use after
   one protected message is transferred from client to server. Given
   this premise, the server now calls GSS_Delete_sec_context() to flush
   context-level information.  Optionally, the server-side application
   may provide a token buffer to GSS_Delete_sec_context(), to receive a
   context_token to be transferred to the client in order to request
   that client-side context-level information be deleted.

   If a context_token is transferred, the client passes the
   context_token to GSS_Process_context_token(), which returns
   GSS_S_COMPLETE status after deleting context-level information at the
   client system.

   The GSS-API design assumes and addresses several basic goals,
   including:

      Mechanism independence: The GSS-API defines an interface to
      cryptographically implemented strong authentication and other
      security services at a generic level which is independent of
      particular underlying mechanisms. For example, GSS-API-provided
      services can be implemented by secret-key technologies (e.g.,
      Kerberos) or public-key approaches (e.g., X.509).

      Protocol environment independence: The GSS-API is independent of
      the communications protocol suites with which it is employed,
      permitting use in a broad range of protocol environments. In
      appropriate environments, an intermediate implementation "veneer"
      which is oriented to a particular communication protocol (e.g.,
      Remote Procedure Call (RPC)) may be interposed between
      applications which call that protocol and the GSS-API, thereby
      invoking GSS-API facilities in conjunction with that protocol's
      communications invocations.

      Protocol association independence: The GSS-API's security context
      construct is independent of communications protocol association



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      constructs. This characteristic allows a single GSS-API
      implementation to be utilized by a variety of invoking protocol
      modules on behalf of those modules' calling applications. GSS-API
      services can also be invoked directly by applications, wholly
      independent of protocol associations.

      Suitability to a range of implementation placements: GSS-API
      clients are not constrained to reside within any Trusted Computing
      Base (TCB) perimeter defined on a system where the GSS-API is
      implemented; security services are specified in a manner suitable
      to both intra-TCB and extra-TCB callers.

1.1: GSS-API Constructs

   This section describes the basic elements comprising the GSS-API.

1.1.1:  Credentials

1.1.1.1: Credential Constructs and Concepts

   Credentials provide the prerequisites which permit GSS-API peers to
   establish security contexts with each other. A caller may designate
   that the credential elements which are to be applied for context
   initiation or acceptance be selected by default.  Alternately, those
   GSS-API callers which need to make explicit selection of particular
   credentials structures may make references to those credentials
   through GSS-API-provided credential handles ("cred_handles").  In all
   cases, callers' credential references are indirect, mediated by GSS-
   API implementations and not requiring callers to access the selected
   credential elements.

   A single credential structure may be used to initiate outbound
   contexts and to accept inbound contexts. Callers needing to operate
   in only one of these modes may designate this fact when credentials
   are acquired for use, allowing underlying mechanisms to optimize
   their processing and storage requirements. The credential elements
   defined by a particular mechanism may contain multiple cryptographic
   keys, e.g., to enable authentication and message encryption to be
   performed with different algorithms.

   A GSS-API credential structure may contain multiple credential
   elements, each containing mechanism-specific information for a
   particular underlying mechanism (mech_type), but the set of elements
   within a given credential structure represent a common entity.  A
   credential structure's contents will vary depending on the set of
   mech_types supported by a particular GSS-API implementation. Each
   credential element identifies the data needed by its mechanism in
   order to establish contexts on behalf of a particular principal, and



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   may contain separate credential references for use in context
   initiation and context acceptance.  Multiple credential elements
   within a given credential having overlapping combinations of
   mechanism, usage mode, and validity period are not permitted.

   Commonly, a single mech_type will be used for all security contexts
   established by a particular initiator to a particular target. A major
   motivation for supporting credential sets representing multiple
   mech_types is to allow initiators on systems which are equipped to
   handle multiple types to initiate contexts to targets on other
   systems which can accommodate only a subset of the set supported at
   the initiator's system.

1.1.1.2: Credential Management

   It is the responsibility of underlying system-specific mechanisms and
   OS functions below the GSS-API to ensure that the ability to acquire
   and use credentials associated with a given identity is constrained
   to appropriate processes within a system. This responsibility should
   be taken seriously by implementors, as the ability for an entity to
   utilize a principal's credentials is equivalent to the entity's
   ability to successfully assert that principal's identity.

   Once a set of GSS-API credentials is established, the transferability
   of that credentials set to other processes or analogous constructs
   within a system is a local matter, not defined by the GSS-API. An
   example local policy would be one in which any credentials received
   as a result of login to a given user account, or of delegation of
   rights to that account, are accessible by, or transferable to,
   processes running under that account.

   The credential establishment process (particularly when performed on
   behalf of users rather than server processes) is likely to require
   access to passwords or other quantities which should be protected
   locally and exposed for the shortest time possible. As a result, it
   will often be appropriate for preliminary credential establishment to
   be performed through local means at user login time, with the
   result(s) cached for subsequent reference. These preliminary
   credentials would be set aside (in a system-specific fashion) for
   subsequent use, either:

      to be accessed by an invocation of the GSS-API GSS_Acquire_cred()
      call, returning an explicit handle to reference that credential

      to comprise default credential elements to be installed, and to be
      used when default credential behavior is requested on behalf of a
      process




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1.1.1.3: Default Credential Resolution

   The gss_init_sec_context and gss_accept_sec_context routines allow
   the value GSS_C_NO_CREDENTIAL to be specified as their credential
   handle parameter.  This special credential-handle indicates a desire
   by the application to act as a default principal.  While individual
   GSS-API implementations are free to determine such default behavior
   as appropriate to the mechanism, the following default behavior by
   these routines is recommended for portability:

   GSS_Init_sec_context:

      (i) If there is only a single principal capable of initiating
      security contexts that the application is authorized to act on
      behalf of, then that principal shall be used, otherwise

      (ii) If the platform maintains a concept of a default network-
      identity, and if the application is authorized to act on behalf of
      that identity for the purpose of initiating security contexts,
      then the principal corresponding to that identity shall be used,
      otherwise

      (iii) If the platform maintains a concept of a default local
      identity, and provides a means to map local identities into
      network-identities, and if the application is authorized to act on
      behalf of the network-identity image of the default local identity
      for the purpose of initiating security contexts, then the
      principal corresponding to that identity shall be used, otherwise

      (iv) A user-configurable default identity should be used.

   GSS_Accept_sec_context:

      (i) If there is only a single authorized principal identity
      capable of accepting security contexts, then that principal shall
      be used, otherwise

      (ii) If the mechanism can determine the identity of the target
      principal by examining the context-establishment token, and if the
      accepting application is authorized to act as that principal for
      the purpose of accepting security contexts, then that principal
      identity shall be used, otherwise

      (iii) If the mechanism supports context acceptance by any
      principal, and mutual authentication was not requested, any
      principal that the application is authorized to accept security
      contexts under may be used, otherwise




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      (iv) A user-configurable default identity shall be used.

   The purpose of the above rules is to allow security contexts to be
   established by both initiator and acceptor using the default behavior
   wherever possible.  Applications requesting default behavior are
   likely to be more portable across mechanisms and platforms than ones
   that use GSS_Acquire_cred to request a specific identity.

1.1.2: Tokens

   Tokens are data elements transferred between GSS-API callers, and are
   divided into two classes. Context-level tokens are exchanged in order
   to establish and manage a security context between peers. Per-message
   tokens relate to an established context and are exchanged to provide
   protective security services (i.e., data origin authentication,
   integrity, and optional confidentiality) for corresponding data
   messages.

   The first context-level token obtained from GSS_Init_sec_context() is
   required to indicate at its very beginning a globally-interpretable
   mechanism identifier, i.e., an Object Identifier (OID) of the
   security mechanism. The remaining part of this token as well as the
   whole content of all other tokens are specific to the particular
   underlying mechanism used to support the GSS-API. Section 3 of this
   document provides, for designers of GSS-API support mechanisms, the
   description of the header of the first context-level token which is
   then followed by mechanism-specific information.

   Tokens' contents are opaque from the viewpoint of GSS-API callers.
   They are generated within the GSS-API implementation at an end
   system, provided to a GSS-API caller to be transferred to the peer
   GSS-API caller at a remote end system, and processed by the GSS-API
   implementation at that remote end system. Tokens may be output by
   GSS-API calls (and should be transferred to GSS-API peers) whether or
   not the calls' status indicators indicate successful completion.
   Token transfer may take place in an in-band manner, integrated into
   the same protocol stream used by the GSS-API callers for other data
   transfers, or in an out-of-band manner across a logically separate
   channel.

   Different GSS-API tokens are used for different purposes (e.g.,
   context initiation, context acceptance, protected message data on an
   established context), and it is the responsibility of a GSS-API
   caller receiving tokens to distinguish their types, associate them
   with corresponding security contexts, and pass them to appropriate
   GSS-API processing routines.  Depending on the caller protocol
   environment, this distinction may be accomplished in several ways.




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   The following examples illustrate means through which tokens' types
   may be distinguished:

      - implicit tagging based on state information (e.g., all tokens on
      a new association are considered to be context establishment
      tokens until context establishment is completed, at which point
      all tokens are considered to be wrapped data objects for that
      context),

      - explicit tagging at the caller protocol level,

      - a hybrid of these approaches.

   Commonly, the encapsulated data within a token includes internal
   mechanism-specific tagging information, enabling mechanism-level
   processing modules to distinguish tokens used within the mechanism
   for different purposes.  Such internal mechanism-level tagging is
   recommended to mechanism designers, and enables mechanisms to
   determine whether a caller has passed a particular token for
   processing by an inappropriate GSS-API routine.

   Development of GSS-API support primitives based on a particular
   underlying cryptographic technique and protocol (i.e., conformant to
   a specific GSS-API mechanism definition) does not necessarily imply
   that GSS-API callers using that GSS-API mechanism will be able to
   interoperate with peers invoking the same technique and protocol
   outside the GSS-API paradigm, or with peers implementing a different
   GSS-API mechanism based on the same underlying technology.  The
   format of GSS-API tokens defined in conjunction with a particular
   mechanism, and the techniques used to integrate those tokens into
   callers' protocols, may not be interoperable with the tokens used by
   non-GSS-API callers of the same underlying technique.

1.1.3:  Security Contexts

   Security contexts are established between peers, using credentials
   established locally in conjunction with each peer or received by
   peers via delegation. Multiple contexts may exist simultaneously
   between a pair of peers, using the same or different sets of
   credentials. Coexistence of multiple contexts using different
   credentials allows graceful rollover when credentials expire.
   Distinction among multiple contexts based on the same credentials
   serves applications by distinguishing different message streams in a
   security sense.

   The GSS-API is independent of underlying protocols and addressing
   structure, and depends on its callers to transport GSS-API-provided
   data elements. As a result of these factors, it is a caller



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   responsibility to parse communicated messages, separating GSS-API-
   related data elements from caller-provided data.  The GSS-API is
   independent of connection vs. connectionless orientation of the
   underlying communications service.

   No correlation between security context and communications protocol
   association is dictated. (The optional channel binding facility,
   discussed in Section 1.1.6 of this document, represents an
   intentional exception to this rule, supporting additional protection
   features within GSS-API supporting mechanisms.) This separation
   allows the GSS-API to be used in a wide range of communications
   environments, and also simplifies the calling sequences of the
   individual calls. In many cases (depending on underlying security
   protocol, associated mechanism, and availability of cached
   information), the state information required for context setup can be
   sent concurrently with initial signed user data, without interposing
   additional message exchanges.

1.1.4:  Mechanism Types

   In order to successfully establish a security context with a target
   peer, it is necessary to identify an appropriate underlying mechanism
   type (mech_type) which both initiator and target peers support. The
   definition of a mechanism embodies not only the use of a particular
   cryptographic technology (or a hybrid or choice among alternative
   cryptographic technologies), but also definition of the syntax and
   semantics of data element exchanges which that mechanism will employ
   in order to support security services.

   It is recommended that callers initiating contexts specify the
   "default" mech_type value, allowing system-specific functions within
   or invoked by the GSS-API implementation to select the appropriate
   mech_type, but callers may direct that a particular mech_type be
   employed when necessary.

   The means for identifying a shared mech_type to establish a security
   context with a peer will vary in different environments and
   circumstances; examples include (but are not limited to):

      use of a fixed mech_type, defined by configuration, within an
      environment

      syntactic convention on a target-specific basis, through
      examination of a target's name

      lookup of a target's name in a naming service or other database in
      order to identify mech_types supported by that target




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      explicit negotiation between GSS-API callers in advance of
      security context setup

   When transferred between GSS-API peers, mech_type specifiers (per
   Section 3, represented as Object Identifiers (OIDs)) serve to qualify
   the interpretation of associated tokens. (The structure and encoding
   of Object Identifiers is defined in ISO/IEC 8824, "Specification of
   Abstract Syntax Notation One (ASN.1)" and in ISO/IEC 8825,
   "Specification of Basic Encoding Rules for Abstract Syntax Notation
   One (ASN.1)".) Use of hierarchically structured OIDs serves to
   preclude ambiguous interpretation of mech_type specifiers. The OID
   representing the DASS MechType, for example, is 1.3.12.2.1011.7.5,
   and that of the Kerberos V5 mechanism, once advanced to the level of
   Proposed Standard, will be 1.2.840.113554.1.2.2.

1.1.5:  Naming

   The GSS-API avoids prescribing naming structures, treating the names
   which are transferred across the interface in order to initiate and
   accept security contexts as opaque objects.  This approach supports
   the GSS-API's goal of implementability atop a range of underlying
   security mechanisms, recognizing the fact that different mechanisms
   process and authenticate names which are presented in different
   forms. Generalized services offering translation functions among
   arbitrary sets of naming environments are outside the scope of the
   GSS-API; availability and use of local conversion functions to
   translate among the naming formats supported within a given end
   system is anticipated.

   Different classes of name representations are used in conjunction
   with different GSS-API parameters:

      - Internal form (denoted in this document by INTERNAL NAME),
      opaque to callers and defined by individual GSS-API
      implementations.  GSS-API implementations supporting multiple
      namespace types must maintain internal tags to disambiguate the
      interpretation of particular names.  A Mechanism Name (MN) is a
      special case of INTERNAL NAME, guaranteed to contain elements
      corresponding to one and only one mechanism; calls which are
      guaranteed to emit MNs or which require MNs as input are so
      identified within this specification.

      - Contiguous string ("flat") form (denoted in this document by
      OCTET STRING); accompanied by OID tags identifying the namespace
      to which they correspond.  Depending on tag value, flat names may
      or may not be printable strings for direct acceptance from and
      presentation to users. Tagging of flat names allows GSS-API
      callers and underlying GSS-API mechanisms to disambiguate name



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      types and to determine whether an associated name's type is one
      which they are capable of processing, avoiding aliasing problems
      which could result from misinterpreting a name of one type as a
      name of another type.

      - The GSS-API Exported Name Object, a special case of flat name
      designated by a reserved OID value, carries a canonicalized form
      of a name suitable for binary comparisons.

   In addition to providing means for names to be tagged with types,
   this specification defines primitives to support a level of naming
   environment independence for certain calling applications. To provide
   basic services oriented towards the requirements of callers which
   need not themselves interpret the internal syntax and semantics of
   names, GSS-API calls for name comparison (GSS_Compare_name()),
   human-readable display (GSS_Display_name()), input conversion
   (GSS_Import_name()), internal name deallocation (GSS_Release_name()),
   and internal name duplication (GSS_Duplicate_name()) functions are
   defined. (It is anticipated that these proposed GSS-API calls will be
   implemented in many end systems based on system-specific name
   manipulation primitives already extant within those end systems;
   inclusion within the GSS-API is intended to offer GSS-API callers a
   portable means to perform specific operations, supportive of
   authorization and audit requirements, on authenticated names.)

   GSS_Import_name() implementations can, where appropriate, support
   more than one printable syntax corresponding to a given namespace
   (e.g., alternative printable representations for X.500 Distinguished
   Names), allowing flexibility for their callers to select among
   alternative representations. GSS_Display_name() implementations
   output a printable syntax selected as appropriate to their
   operational environments; this selection is a local matter. Callers
   desiring portability across alternative printable syntaxes should
   refrain from implementing comparisons based on printable name forms
   and should instead use the GSS_Compare_name()  call to determine
   whether or not one internal-format name matches another.

   The GSS_Canonicalize_name() and GSS_Export_name() calls enable
   callers to acquire and process Exported Name Objects, canonicalized
   and translated in accordance with the procedures of a particular
   GSS-API mechanism.  Exported Name Objects can, in turn, be input to
   GSS_Import_name(), yielding equivalent MNs. These facilities are
   designed specifically to enable efficient storage and comparison of
   names (e.g., for use in access control lists).







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   The following diagram illustrates the intended dataflow among name-
   related GSS-API processing routines.

                        GSS-API library defaults
                               |
                               |
                               V                         text, for
   text -------------->  internal_name (IN) -----------> display only
         import_name()          /          display_name()
                               /
                              /
                             /
    accept_sec_context()    /
          |                /
          |               /
          |              /  canonicalize_name()
          |             /
          |            /
          |           /
          |          /
          |         /
          |        |
          V        V     <---------------------
    single mechanism        import_name()         exported name: flat
    internal_name (MN)                            binary "blob" usable
                         ---------------------->  for access control
                            export_name()

1.1.6:  Channel Bindings

   The GSS-API accommodates the concept of caller-provided channel
   binding ("chan_binding") information.  Channel bindings are used to
   strengthen the quality with which peer entity authentication is
   provided during context establishment, by limiting the scope within
   which an intercepted context establishment token can be reused by an
   attacker. Specifically, they enable GSS-API callers to bind the
   establishment of a security context to relevant characteristics
   (e.g., addresses, transformed representations of encryption keys) of
   the underlying communications channel, of protection mechanisms
   applied to that communications channel, and to application-specific
   data.

   The caller initiating a security context must determine the
   appropriate channel binding values to provide as input to the
   GSS_Init_sec_context() call, and consistent values must be provided
   to GSS_Accept_sec_context() by the context's target, in order for
   both peers' GSS-API mechanisms to validate that received tokens
   possess correct channel-related characteristics. Use or non-use of



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   the GSS-API channel binding facility is a caller option.  GSS-API
   mechanisms can operate in an environment where NULL channel bindings
   are presented; mechanism implementors are encouraged, but not
   required, to make use of caller-provided channel binding data within
   their mechanisms. Callers should not assume that underlying
   mechanisms provide confidentiality protection for channel binding
   information.

   When non-NULL channel bindings are provided by callers, certain
   mechanisms can offer enhanced security value by interpreting the
   bindings' content (rather than simply representing those bindings, or
   integrity check values computed on them, within tokens) and will
   therefore depend on presentation of specific data in a defined
   format. To this end, agreements among mechanism implementors are
   defining conventional interpretations for the contents of channel
   binding arguments, including address specifiers (with content
   dependent on communications protocol environment) for context
   initiators and acceptors. (These conventions are being incorporated
   in GSS-API mechanism specifications and into the GSS-API C language
   bindings specification.) In order for GSS-API callers to be portable
   across multiple mechanisms and achieve the full security
   functionality which each mechanism can provide, it is strongly
   recommended that GSS-API callers provide channel bindings consistent
   with these conventions and those of the networking environment in
   which they operate.

1.2:  GSS-API Features and Issues

   This section describes aspects of GSS-API operations, of the security
   services which the GSS-API provides, and provides commentary on
   design issues.

1.2.1:  Status Reporting

   Each GSS-API call provides two status return values. Major_status
   values provide a mechanism-independent indication of call status
   (e.g., GSS_S_COMPLETE, GSS_S_FAILURE, GSS_S_CONTINUE_NEEDED),
   sufficient to drive normal control flow within the caller in a
   generic fashion. Table 1 summarizes the defined major_status return
   codes in tabular fashion.











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Table 1: GSS-API Major Status Codes

   FATAL ERROR CODES

   GSS_S_BAD_BINDINGS            channel binding mismatch
   GSS_S_BAD_MECH                unsupported mechanism requested
   GSS_S_BAD_NAME                invalid name provided
   GSS_S_BAD_NAMETYPE            name of unsupported type provided
   GSS_S_BAD_STATUS              invalid input status selector
   GSS_S_BAD_SIG                 token had invalid integrity check
   GSS_S_CONTEXT_EXPIRED         specified security context expired
   GSS_S_CREDENTIALS_EXPIRED     expired credentials detected
   GSS_S_DEFECTIVE_CREDENTIAL    defective credential detected
   GSS_S_DEFECTIVE_TOKEN         defective token detected
   GSS_S_FAILURE                 failure, unspecified at GSS-API
                                   level
   GSS_S_NO_CONTEXT              no valid security context specified
   GSS_S_NO_CRED                 no valid credentials provided
   GSS_S_BAD_QOP                 unsupported QOP value
   GSS_S_UNAUTHORIZED            operation unauthorized
   GSS_S_UNAVAILABLE             operation unavailable
   GSS_S_DUPLICATE_ELEMENT       duplicate credential element requested
   GSS_S_NAME_NOT_MN             name contains multi-mechanism elements

   INFORMATORY STATUS CODES

   GSS_S_COMPLETE                normal completion
   GSS_S_CONTINUE_NEEDED         continuation call to routine
                                  required
   GSS_S_DUPLICATE_TOKEN         duplicate per-message token
                                  detected
   GSS_S_OLD_TOKEN               timed-out per-message token
                                  detected
   GSS_S_UNSEQ_TOKEN             reordered (early) per-message token
                                  detected
   GSS_S_GAP_TOKEN               skipped predecessor token(s)
                                  detected

   Minor_status provides more detailed status information which may
   include status codes specific to the underlying security mechanism.
   Minor_status values are not specified in this document.

   GSS_S_CONTINUE_NEEDED major_status returns, and optional message
   outputs, are provided in GSS_Init_sec_context() and
   GSS_Accept_sec_context()  calls so that different mechanisms'
   employment of different numbers of messages within their
   authentication sequences need not be reflected in separate code paths
   within calling applications. Instead, such cases are accommodated



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   with sequences of continuation calls to GSS_Init_sec_context()  and
   GSS_Accept_sec_context().  The same mechanism is used to encapsulate
   mutual authentication within the GSS-API's context initiation calls.

   For mech_types which require interactions with third-party servers in
   order to establish a security context, GSS-API context establishment
   calls may block pending completion of such third-party interactions.

   On the other hand, no GSS-API calls pend on serialized interactions
   with GSS-API peer entities.  As a result, local GSS-API status
   returns cannot reflect unpredictable or asynchronous exceptions
   occurring at remote peers, and reflection of such status information
   is a caller responsibility outside the GSS-API.

1.2.2: Per-Message Security Service Availability

   When a context is established, two flags are returned to indicate the
   set of per-message protection security services which will be
   available on the context:

      the integ_avail flag indicates whether per-message integrity and
      data origin authentication services are available

      the conf_avail flag indicates whether per-message confidentiality
      services are available, and will never be returned TRUE unless the
      integ_avail flag is also returned TRUE

      GSS-API callers desiring per-message security services should
      check the values of these flags at context establishment time, and
      must be aware that a returned FALSE value for integ_avail means
      that invocation of GSS_GetMIC()  or GSS_Wrap() primitives on the
      associated context will apply no cryptographic protection to user
      data messages.

   The GSS-API per-message integrity and data origin authentication
   services provide assurance to a receiving caller that protection was
   applied to a message by the caller's peer on the security context,
   corresponding to the entity named at context initiation.  The GSS-API
   per-message confidentiality service provides assurance to a sending
   caller that the message's content is protected from access by
   entities other than the context's named peer.










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   The GSS-API per-message protection service primitives, as the
   category name implies, are oriented to operation at the granularity
   of protocol data units. They perform cryptographic operations on the
   data units, transfer cryptographic control information in tokens,
   and, in the case of GSS_Wrap(), encapsulate the protected data unit.
   As such, these primitives are not oriented to efficient data
   protection for stream-paradigm protocols (e.g., Telnet) if
   cryptography must be applied on an octet-by-octet basis.

1.2.3: Per-Message Replay Detection and Sequencing

   Certain underlying mech_types offer support for replay detection
   and/or sequencing of messages transferred on the contexts they
   support. These optionally-selectable protection features are distinct
   from replay detection and sequencing features applied to the context
   establishment operation itself; the presence or absence of context-
   level replay or sequencing features is wholly a function of the
   underlying mech_type's capabilities, and is not selected or omitted
   as a caller option.

   The caller initiating a context provides flags (replay_det_req_flag
   and sequence_req_flag) to specify whether the use of per-message
   replay detection and sequencing features is desired on the context
   being established. The GSS-API implementation at the initiator system
   can determine whether these features are supported (and whether they
   are optionally selectable) as a function of mech_type, without need
   for bilateral negotiation with the target. When enabled, these
   features provide recipients with indicators as a result of GSS-API
   processing of incoming messages, identifying whether those messages
   were detected as duplicates or out-of-sequence. Detection of such
   events does not prevent a suspect message from being provided to a
   recipient; the appropriate course of action on a suspect message is a
   matter of caller policy.

   The semantics of the replay detection and sequencing services applied
   to received messages, as visible across the interface which the GSS-
   API provides to its clients, are as follows:

   When replay_det_state is TRUE, the possible major_status returns for
   well-formed and correctly signed messages are as follows:

      1. GSS_S_COMPLETE indicates that the message was within the window
      (of time or sequence space) allowing replay events to be detected,
      and that the message was not a replay of a previously-processed
      message within that window.






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      2. GSS_S_DUPLICATE_TOKEN indicates that the cryptographic
      checkvalue on the received message was correct, but that the
      message was recognized as a duplicate of a previously-processed
      message.

      3. GSS_S_OLD_TOKEN indicates that the cryptographic checkvalue on
      the received message was correct, but that the message is too old
      to be checked for duplication.

   When sequence_state is TRUE, the possible major_status returns for
   well-formed and correctly signed messages are as follows:

      1. GSS_S_COMPLETE indicates that the message was within the window
      (of time or sequence space) allowing replay events to be detected,
      that the message was not a replay of a previously-processed
      message within that window, and that no predecessor sequenced
      messages are missing relative to the last received message (if
      any) processed on the context with a correct cryptographic
      checkvalue.

      2. GSS_S_DUPLICATE_TOKEN indicates that the integrity check value
      on the received message was correct, but that the message was
      recognized as a duplicate of a previously-processed message.

      3. GSS_S_OLD_TOKEN indicates that the integrity check value on the
      received message was correct, but that the token is too old to be
      checked for duplication.

      4. GSS_S_UNSEQ_TOKEN indicates that the cryptographic checkvalue
      on the received message was correct, but that it is earlier in a
      sequenced stream than a message already processed on the context.
      [Note: Mechanisms can be architected to provide a stricter form of
      sequencing service, delivering particular messages to recipients
      only after all predecessor messages in an ordered stream have been
      delivered.  This type of support is incompatible with the GSS-API
      paradigm in which recipients receive all messages, whether in
      order or not, and provide them (one at a time, without intra-GSS-
      API message buffering) to GSS-API routines for validation.  GSS-
      API facilities provide supportive functions, aiding clients to
      achieve strict message stream integrity in an efficient manner in
      conjunction with sequencing provisions in communications
      protocols, but the GSS-API does not offer this level of message
      stream integrity service by itself.]








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      5. GSS_S_GAP_TOKEN indicates that the cryptographic checkvalue on
      the received message was correct, but that one or more predecessor
      sequenced messages have not been successfully processed relative
      to the last received message (if any) processed on the context
      with a correct cryptographic checkvalue.

   As the message stream integrity features (especially sequencing) may
   interfere with certain applications' intended communications
   paradigms, and since support for such features is likely to be
   resource intensive, it is highly recommended that mech_types
   supporting these features allow them to be activated selectively on
   initiator request when a context is established. A context initiator
   and target are provided with corresponding indicators
   (replay_det_state and sequence_state), signifying whether these
   features are active on a given context.

   An example mech_type supporting per-message replay detection could
   (when replay_det_state is TRUE) implement the feature as follows: The
   underlying mechanism would insert timestamps in data elements output
   by GSS_GetMIC()  and GSS_Wrap(), and would maintain (within a time-
   limited window) a cache (qualified by originator-recipient pair)
   identifying received data elements processed by GSS_VerifyMIC()  and
   GSS_Unwrap(). When this feature is active, exception status returns
   (GSS_S_DUPLICATE_TOKEN, GSS_S_OLD_TOKEN) will be provided when
   GSS_VerifyMIC()  or GSS_Unwrap() is presented with a message which is
   either a detected duplicate of a prior message or which is too old to
   validate against a cache of recently received messages.

1.2.4:  Quality of Protection

   Some mech_types provide their users with fine granularity control
   over the means used to provide per-message protection, allowing
   callers to trade off security processing overhead dynamically against
   the protection requirements of particular messages. A per-message
   quality-of-protection parameter (analogous to quality-of-service, or
   QOS) selects among different QOP options supported by that mechanism.
   On context establishment for a multi-QOP mech_type, context-level
   data provides the prerequisite data for a range of protection
   qualities.

   It is expected that the majority of callers will not wish to exert
   explicit mechanism-specific QOP control and will therefore request
   selection of a default QOP. Definitions of, and choices among, non-
   default QOP values are mechanism-specific, and no ordered sequences
   of QOP values can be assumed equivalent across different mechanisms.
   Meaningful use of non-default QOP values demands that callers be
   familiar with the QOP definitions of an underlying mechanism or
   mechanisms, and is therefore a non-portable construct.  The



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   GSS_S_BAD_QOP major_status value is defined in order to indicate that
   a provided QOP value is unsupported for a security context, most
   likely because that value is unrecognized by the underlying
   mechanism.

1.2.5: Anonymity Support

   In certain situations or environments, an application may wish to
   authenticate a peer and/or protect communications using GSS-API per-
   message services without revealing its own identity.  For example,
   consider an application which provides read access to a research
   database, and which permits queries by arbitrary requestors.  A
   client of such a service might wish to authenticate the service, to
   establish trust in the information received from it, but might not
   wish to disclose its identity to the service for privacy reasons.

   In ordinary GSS-API usage, a context initiator's identity is made
   available to the context acceptor as part of the context
   establishment process.  To provide for anonymity support, a facility
   (input anon_req_flag to GSS_Init_sec_context()) is provided through
   which context initiators may request that their identity not be
   provided to the context acceptor.  Mechanisms are not required to
   honor this request, but a caller will be informed (via returned
   anon_state indicator from GSS_Init_sec_context()) whether or not the
   request is honored. Note that authentication as the anonymous
   principal does not necessarily imply that credentials are not
   required in order to establish a context.

   The following Object Identifier value is provided as a means to
   identify anonymous names, and can be compared against in order to
   determine, in a mechanism-independent fashion, whether a name refers
   to an anonymous principal:

   {1(iso), 3(org), 6(dod), 1(internet), 5(security), 6(nametypes),
   3(gss-anonymous-name)}

   The recommended symbolic name corresponding to this definition is
   GSS_C_NT_ANONYMOUS.

   Four possible combinations of anon_state and mutual_state are
   possible, with the following results:

      anon_state == FALSE, mutual_state == FALSE: initiator
      authenticated to target.

      anon_state == FALSE, mutual_state == TRUE: initiator authenticated
      to target, target authenticated to initiator.




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      anon_state == TRUE, mutual_state == FALSE: initiator authenticated
      as anonymous principal to target.

      anon_state == TRUE, mutual_state == TRUE: initiator authenticated
      as anonymous principal to target, target authenticated to
      initiator.

1.2.6: Initialization

   No initialization calls (i.e., calls which must be invoked prior to
   invocation of other facilities in the interface) are defined in GSS-
   API.  As an implication of this fact, GSS-API implementations must
   themselves be self-initializing.

1.2.7: Per-Message Protection During Context Establishment

   A facility is defined in GSS-V2 to enable protection and buffering of
   data messages for later transfer while a security context's
   establishment is in GSS_S_CONTINUE_NEEDED status, to be used in cases
   where the caller side already possesses the necessary session key to
   enable this processing. Specifically, a new state Boolean, called
   prot_ready_state, is added to the set of information returned by
   GSS_Init_sec_context(), GSS_Accept_sec_context(), and
   GSS_Inquire_context().

   For context establishment calls, this state Boolean is valid and
   interpretable when the associated major_status is either
   GSS_S_CONTINUE_NEEDED, or GSS_S_COMPLETE.  Callers of GSS-API (both
   initiators and acceptors) can assume that per-message protection (via
   GSS_Wrap(), GSS_Unwrap(), GSS_GetMIC() and GSS_VerifyMIC()) is
   available and ready for use if either: prot_ready_state == TRUE, or
   major_status == GSS_S_COMPLETE, though mutual authentication (if
   requested) cannot be guaranteed until GSS_S_COMPLETE is returned.

   This achieves full, transparent backward compatibility for GSS-API V1
   callers, who need not even know of the existence of prot_ready_state,
   and who will get the expected behavior from GSS_S_COMPLETE, but who
   will not be able to use per-message protection before GSS_S_COMPLETE
   is returned.

   It is not a requirement that GSS-V2 mechanisms ever return TRUE
   prot_ready_state before completion of context establishment (indeed,
   some mechanisms will not evolve usable message protection keys,
   especially at the context acceptor, before context establishment is
   complete).  It is expected but not required that GSS-V2 mechanisms
   will return TRUE prot_ready_state upon completion of context
   establishment if they support per-message protection at all (however
   GSS-V2 applications should not assume that TRUE prot_ready_state will



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   always be returned together with the GSS_S_COMPLETE major_status,
   since GSS-V2 implementations may continue to support GSS-V1 mechanism
   code, which will never return TRUE prot_ready_state).

   When prot_ready_state is returned TRUE, mechanisms shall also set
   those context service indicator flags (deleg_state, mutual_state,
   replay_det_state, sequence_state, anon_state, trans_state,
   conf_avail, integ_avail) which represent facilities confirmed, at
   that time, to be available on the context being established.  In
   situations where prot_ready_state is returned before GSS_S_COMPLETE,
   it is possible that additional facilities may be confirmed and
   subsequently indicated when GSS_S_COMPLETE is returned.

1.2.8: Implementation Robustness

   This section recommends aspects of GSS-API implementation behavior in
   the interests of overall robustness.

   If a token is presented for processing on a GSS-API security context
   and that token is determined to be invalid for that context, the
   context's state should not be disrupted for purposes of processing
   subsequent valid tokens.

   Certain local conditions at a GSS-API implementation (e.g.,
   unavailability of memory) may preclude, temporarily or permanently,
   the successful processing of tokens on a GSS-API security context,
   typically generating GSS_S_FAILURE major_status returns along with
   locally-significant minor_status.  For robust operation under such
   conditions, the following recommendations are made:

      Failing calls should free any memory they allocate, so that
      callers may retry without causing further loss of resources.

      Failure of an individual call on an established context should not
      preclude subsequent calls from succeeding on the same context.

      Whenever possible, it should be possible for
      GSS_Delete_sec_context() calls to be successfully processed even
      if other calls cannot succeed, thereby enabling context-related
      resources to be released.

2:  Interface Descriptions

   This section describes the GSS-API's service interface, dividing the
   set of calls offered into four groups. Credential management calls
   are related to the acquisition and release of credentials by
   principals. Context-level calls are related to the management of
   security contexts between principals. Per-message calls are related



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   to the protection of individual messages on established security
   contexts. Support calls provide ancillary functions useful to GSS-API
   callers. Table 2 groups and summarizes the calls in tabular fashion.

Table 2:  GSS-API Calls

   CREDENTIAL MANAGEMENT

   GSS_Acquire_cred             acquire credentials for use
   GSS_Release_cred             release credentials after use
   GSS_Inquire_cred             display information about
                                credentials
   GSS_Add_cred                 construct credentials incrementally
   GSS_Inquire_cred_by_mech     display per-mechanism credential
                                information

   CONTEXT-LEVEL CALLS

   GSS_Init_sec_context         initiate outbound security context
   GSS_Accept_sec_context       accept inbound security context
   GSS_Delete_sec_context       flush context when no longer needed
   GSS_Process_context_token    process received control token on
                                context
   GSS_Context_time             indicate validity time remaining on
                                      context
   GSS_Inquire_context          display information about context
   GSS_Wrap_size_limit          determine GSS_Wrap token size limit
   GSS_Export_sec_context       transfer context to other process
   GSS_Import_sec_context       import transferred context

   PER-MESSAGE CALLS

   GSS_GetMIC                   apply integrity check, receive as
                                token separate from message
   GSS_VerifyMIC                validate integrity check token
                                along with message
   GSS_Wrap                     sign, optionally encrypt,
                                encapsulate
   GSS_Unwrap                   decapsulate, decrypt if needed,
                                validate integrity check











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   SUPPORT CALLS

   GSS_Display_status           translate status codes to printable
                                form
   GSS_Indicate_mechs           indicate mech_types supported on
                                local system
   GSS_Compare_name             compare two names for equality
   GSS_Display_name             translate name to printable form
   GSS_Import_name              convert printable name to
                                normalized form
   GSS_Release_name             free storage of normalized-form
                                name
   GSS_Release_buffer           free storage of printable name
   GSS_Release_OID              free storage of OID object
   GSS_Release_OID_set          free storage of OID set object
   GSS_Create_empty_OID_set     create empty OID set
   GSS_Add_OID_set_member       add member to OID set
   GSS_Test_OID_set_member      test if OID is member of OID set
   GSS_OID_to_str               display OID as string
   GSS_Str_to_OID               construct OID from string
   GSS_Inquire_names_for_mech   indicate name types supported by
                                mechanism
   GSS_Inquire_mechs_for_name   indicates mechanisms supporting name
                                type
   GSS_Canonicalize_name        translate name to per-mechanism form
   GSS_Export_name              externalize per-mechanism name
   GSS_Duplicate_name           duplicate name object

2.1:  Credential management calls

   These GSS-API calls provide functions related to the management of
   credentials. Their characterization with regard to whether or not
   they may block pending exchanges with other network entities (e.g.,
   directories or authentication servers) depends in part on OS-specific
   (extra-GSS-API) issues, so is not specified in this document.

   The GSS_Acquire_cred() call is defined within the GSS-API in support
   of application portability, with a particular orientation towards
   support of portable server applications. It is recognized that (for
   certain systems and mechanisms) credentials for interactive users may
   be managed differently from credentials for server processes; in such
   environments, it is the GSS-API implementation's responsibility to
   distinguish these cases and the procedures for making this
   distinction are a local matter. The GSS_Release_cred()  call provides
   a means for callers to indicate to the GSS-API that use of a
   credentials structure is no longer required. The GSS_Inquire_cred()
   call allows callers to determine information about a credentials
   structure.  The GSS_Add_cred() call enables callers to append



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   elements to an existing credential structure, allowing iterative
   construction of a multi-mechanism credential. The
   GSS_Inquire_cred_by_mech() call enables callers to extract per-
   mechanism information describing a credentials structure.

2.1.1:  GSS_Acquire_cred call

   Inputs:

   o  desired_name INTERNAL NAME, -NULL requests locally-determined
      default

   o  lifetime_req INTEGER,-in seconds; 0 requests default

   o  desired_mechs SET OF OBJECT IDENTIFIER,-empty set requests
      system-selected default

   o  cred_usage INTEGER -0=INITIATE-AND-ACCEPT, 1=INITIATE-ONLY,
      2=ACCEPT-ONLY

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  output_cred_handle CREDENTIAL HANDLE,

   o  actual_mechs SET OF OBJECT IDENTIFIER,

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

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that requested credentials were
      successfully established, for the duration indicated in
      lifetime_rec, suitable for the usage requested in cred_usage,
      for the set of mech_types indicated in actual_mechs, and that
      those credentials can be referenced for subsequent use with
      the handle returned in output_cred_handle.

   o  GSS_S_BAD_MECH indicates that a mech_type unsupported by the
      GSS-API implementation type was requested, causing the
      credential establishment operation to fail.






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   o  GSS_S_BAD_NAMETYPE indicates that the provided desired_name is
      uninterpretable or of a type unsupported by the applicable
      underlying GSS-API mechanism(s), so no credentials could be
      established for the accompanying desired_name.

   o  GSS_S_BAD_NAME indicates that the provided desired_name is
      inconsistent in terms of internally-incorporated type specifier
      information, so no credentials could be established for the
      accompanying desired_name.

   o  GSS_S_FAILURE indicates that credential establishment failed
      for reasons unspecified at the GSS-API level, including lack
      of authorization to establish and use credentials associated
      with the identity named in the input desired_name argument.

   GSS_Acquire_cred()  is used to acquire credentials so that a
   principal can (as a function of the input cred_usage parameter)
   initiate and/or accept security contexts under the identity
   represented by the desired_name input argument. On successful
   completion, the returned output_cred_handle result provides a handle
   for subsequent references to the acquired credentials.  Typically,
   single-user client processes requesting that default credential
   behavior be applied for context establishment purposes will have no
   need to invoke this call.

   A caller may provide the value NULL for desired_name, signifying a
   request for credentials corresponding to a principal identity
   selected by default for the caller. The procedures used by GSS-API
   implementations to select the appropriate principal identity in
   response to such a request are local matters. It is possible that
   multiple pre-established credentials may exist for the same principal
   identity (for example, as a result of multiple user login sessions)
   when GSS_Acquire_cred() is called; the means used in such cases to
   select a specific credential are local matters.  The input
   lifetime_req argument to GSS_Acquire_cred() may provide useful
   information for local GSS-API implementations to employ in making
   this disambiguation in a manner which will best satisfy a caller's
   intent.

   The lifetime_rec result indicates the length of time for which the
   acquired credentials will be valid, as an offset from the present. A
   mechanism may return a reserved value indicating INDEFINITE if no
   constraints on credential lifetime are imposed.  A caller of
   GSS_Acquire_cred()  can request a length of time for which acquired
   credentials are to be valid (lifetime_req argument), beginning at the
   present, or can request credentials with a default validity interval.
   (Requests for postdated credentials are not supported within the
   GSS-API.) Certain mechanisms and implementations may bind in



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   credential validity period specifiers at a point preliminary to
   invocation of the GSS_Acquire_cred() call (e.g., in conjunction with
   user login procedures). As a result, callers requesting non-default
   values for lifetime_req must recognize that such requests cannot
   always be honored and must be prepared to accommodate the use of
   returned credentials with different lifetimes as indicated in
   lifetime_rec.

   The caller of GSS_Acquire_cred()  can explicitly specify a set of
   mech_types which are to be accommodated in the returned credentials
   (desired_mechs argument), or can request credentials for a system-
   defined default set of mech_types. Selection of the system-specified
   default set is recommended in the interests of application
   portability. The actual_mechs return value may be interrogated by the
   caller to determine the set of mechanisms with which the returned
   credentials may be used.

2.1.2:  GSS_Release_cred call

   Input:

   o  cred_handle CREDENTIAL HANDLE - NULL specifies that
      the credential elements used when default credential behavior
      is requested be released.

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the credentials referenced by the
      input cred_handle were released for purposes of subsequent
      access by the caller. The effect on other processes which may
      be authorized shared access to such credentials is a local
      matter.

   o  GSS_S_NO_CRED indicates that no release operation was
      performed, either because the input cred_handle was invalid or
      because the caller lacks authorization to access the
      referenced credentials.

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





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   Provides a means for a caller to explicitly request that credentials
   be released when their use is no longer required. Note that system-
   specific credential management functions are also likely to exist,
   for example to assure that credentials shared among processes are
   properly deleted when all affected processes terminate, even if no
   explicit release requests are issued by those processes. Given the
   fact that multiple callers are not precluded from gaining authorized
   access to the same credentials, invocation of GSS_Release_cred()
   cannot be assumed to delete a particular set of credentials on a
   system-wide basis.

2.1.3:  GSS_Inquire_cred call

   Input:

   o  cred_handle CREDENTIAL HANDLE -NULL specifies that the
      credential elements used when default credential behavior is
      requested are to be queried

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  cred_name INTERNAL NAME,

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

   o  cred_usage INTEGER, -0=INITIATE-AND-ACCEPT, 1=INITIATE-ONLY,
      2=ACCEPT-ONLY

   o  mech_set SET OF OBJECT IDENTIFIER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the credentials referenced by the
      input cred_handle argument were valid, and that the output
      cred_name, lifetime_rec, and cred_usage values represent,
      respectively, the credentials' associated principal name,
      remaining lifetime, suitable usage modes, and supported
      mechanism types.

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



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   o  GSS_S_DEFECTIVE_CREDENTIAL indicates that the referenced
      credentials are invalid.

   o  GSS_S_CREDENTIALS_EXPIRED indicates that the referenced
      credentials have expired.

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

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

   For a multi-mechanism credential, the returned "lifetime" specifier
   indicates the shortest lifetime of any of the mechanisms' elements in
   the credential (for either context initiation or acceptance
   purposes).

   GSS_Inquire_cred() should indicate INITIATE-AND-ACCEPT for
   "cred_usage" if both of the following conditions hold:

      (1) there exists in the credential an element which allows context
      initiation using some mechanism

      (2) there exists in the credential an element which allows context
      acceptance using some mechanism (allowably, but not necessarily,
      one of the same mechanism(s) qualifying for (1)).

   If condition (1) holds but not condition (2), GSS_Inquire_cred()
   should indicate INITIATE-ONLY for "cred_usage".  If condition (2)
   holds but not condition (1), GSS_Inquire_cred() should indicate
   ACCEPT-ONLY for "cred_usage".

   Callers requiring finer disambiguation among available combinations
   of lifetimes, usage modes, and mechanisms should call the
   GSS_Inquire_cred_by_mech() routine, passing that routine one of the
   mech OIDs returned by GSS_Inquire_cred().











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2.1.4:  GSS_Add_cred call

   Inputs:

   o  input_cred_handle CREDENTIAL HANDLE - handle to credential
      structure created with prior GSS_Acquire_cred() or
      GSS_Add_cred() call, or NULL to append elements to the set
      which are applied for the caller when default credential
      behavior is specified.

   o  desired_name INTERNAL NAME - NULL requests locally-determined
      default

   o  initiator_time_req INTEGER - in seconds; 0 requests default

   o  acceptor_time_req INTEGER - in seconds; 0 requests default

   o  desired_mech OBJECT IDENTIFIER

   o  cred_usage INTEGER - 0=INITIATE-AND-ACCEPT, 1=INITIATE-ONLY,
       2=ACCEPT-ONLY

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  output_cred_handle CREDENTIAL HANDLE, - NULL to request that
      credential elements be added "in place" to the credential
      structure  identified by input_cred_handle, non-NULL pointer
      to request that a new credential structure and handle be created.

   o  actual_mechs SET OF OBJECT IDENTIFIER,

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

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

   o  cred_usage INTEGER, -0=INITIATE-AND-ACCEPT, 1=INITIATE-ONLY,
      2=ACCEPT-ONLY

   o  mech_set SET OF OBJECT IDENTIFIER -- full set of mechanisms
      supported by resulting credential.





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   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the credentials referenced by
      the input_cred_handle argument were valid, and that the
      resulting credential from GSS_Add_cred() is valid for the
      durations indicated in initiator_time_rec and acceptor_time_rec,
      suitable for the usage requested in cred_usage, and for the
      mechanisms indicated in actual_mechs.

   o  GSS_S_DUPLICATE_ELEMENT indicates that the input desired_mech
      specified a mechanism for which the referenced credential
      already contained a credential element with overlapping
      cred_usage and validity time specifiers.

   o  GSS_S_BAD_MECH indicates that the input desired_mech specified
      a mechanism unsupported by the GSS-API implementation, causing
      the GSS_Add_cred() operation to fail.

   o  GSS_S_BAD_NAMETYPE indicates that the provided desired_name
      is uninterpretable or of a type unsupported by the applicable
      underlying GSS-API mechanism(s), so the GSS_Add_cred() operation
      could not be performed for that name.

   o  GSS_S_BAD_NAME indicates that the provided desired_name is
      inconsistent in terms of internally-incorporated type specifier
      information, so the GSS_Add_cred() operation could not be
      performed for that name.

   o  GSS_S_NO_CRED indicates that the input_cred_handle referenced
      invalid or inaccessible credentials.

   o  GSS_S_FAILURE indicates that the operation failed for
      reasons unspecified at the GSS-API level, including lack of
      authorization to establish or use credentials representing
      the requested identity.

   GSS_Add_cred() enables callers to construct credentials iteratively
   by adding credential elements in successive operations, corresponding
   to different mechanisms.  This offers particular value in multi-
   mechanism environments, as the major_status and minor_status values
   returned on each iteration are individually visible and can therefore
   be interpreted unambiguously on a per-mechanism basis.

   The same input desired_name, or default reference, should be used on
   all GSS_Acquire_cred() and GSS_Add_cred() calls corresponding to a
   particular credential.





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2.1.5:  GSS_Inquire_cred_by_mech call

   Inputs:

   o  cred_handle CREDENTIAL HANDLE  -- NULL specifies that the
      credential elements used when default credential behavior is
      requested are to be queried

   o  mech_type OBJECT IDENTIFIER  -- specific mechanism for
      which credentials are being queried

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  cred_name INTERNAL NAME, -- guaranteed to be MN

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

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

   o  cred_usage INTEGER, -0=INITIATE-AND-ACCEPT, 1=INITIATE-ONLY,
      2=ACCEPT-ONLY

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the credentials referenced by the
      input cred_handle argument were valid, that the mechanism
      indicated by the input mech_type was represented with elements
      within those credentials, and that the output cred_name,
      lifetime_rec_initiate, lifetime_rec_accept, and cred_usage values
      represent, respectively, the credentials' associated principal
      name, remaining lifetimes, and suitable usage modes.

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

   o  GSS_S_DEFECTIVE_CREDENTIAL indicates that the referenced
      credentials are invalid.

   o  GSS_S_CREDENTIALS_EXPIRED indicates that the referenced
      credentials have expired.



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   o  GSS_S_BAD_MECH indicates that the referenced credentials do not
      contain elements for the requested mechanism.

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

   The GSS_Inquire_cred_by_mech() call enables callers in multi-
   mechanism environments to acquire specific data about available
   combinations of lifetimes, usage modes, and mechanisms within a
   credential structure.  The lifetime_rec_initiate result indicates the
   available lifetime for context initiation purposes; the
   lifetime_rec_accept result indicates the available lifetime for
   context acceptance purposes.

2.2:  Context-level calls

   This group of calls is devoted to the establishment and management of
   security contexts between peers. A context's initiator calls
   GSS_Init_sec_context(),  resulting in generation of a token which the
   caller passes to the target. At the target, that token is passed to
   GSS_Accept_sec_context().  Depending on the underlying mech_type and
   specified options, additional token exchanges may be performed in the
   course of context establishment; such exchanges are accommodated by
   GSS_S_CONTINUE_NEEDED status returns from GSS_Init_sec_context()  and
   GSS_Accept_sec_context().

   Either party to an established context may invoke
   GSS_Delete_sec_context() to flush context information when a context
   is no longer required. GSS_Process_context_token()  is used to
   process received tokens carrying context-level control information.
   GSS_Context_time()  allows a caller to determine the length of time
   for which an established context will remain valid.
   GSS_Inquire_context() returns status information describing context
   characteristics. GSS_Wrap_size_limit() allows a caller to determine
   the size of a token which will be generated by a GSS_Wrap()
   operation.  GSS_Export_sec_context() and GSS_Import_sec_context()
   enable transfer of active contexts between processes on an end
   system.

2.2.1:  GSS_Init_sec_context call

   Inputs:

   o  claimant_cred_handle CREDENTIAL HANDLE, -NULL specifies "use
      default"

   o  input_context_handle CONTEXT HANDLE, -0 specifies "none assigned
      yet"



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   o  targ_name INTERNAL NAME,

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

   o  deleg_req_flag BOOLEAN,

   o  mutual_req_flag BOOLEAN,

   o  replay_det_req_flag BOOLEAN,

   o  sequence_req_flag BOOLEAN,

   o  anon_req_flag BOOLEAN,

   o  lifetime_req INTEGER,-0 specifies default lifetime

   o  chan_bindings OCTET STRING,

   o  input_token OCTET STRING-NULL or token received from target

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  output_context_handle CONTEXT HANDLE,

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

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

   o  deleg_state BOOLEAN,

   o  mutual_state BOOLEAN,

   o  replay_det_state BOOLEAN,

   o  sequence_state BOOLEAN,

   o  anon_state BOOLEAN,

   o  trans_state BOOLEAN,

   o  prot_ready_state BOOLEAN, -- see Section 1.2.7



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   o  conf_avail BOOLEAN,

   o  integ_avail BOOLEAN,

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

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

   Return major_status codes:

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

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

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

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

   o  GSS_S_BAD_SIG indicates that the received input_token
      contains an incorrect integrity check, so context setup cannot
      be accomplished.

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

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



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

   o  GSS_S_OLD_TOKEN indicates that the input_token is too old to
      be checked for integrity. This is a fatal error during context
      establishment.

   o  GSS_S_DUPLICATE_TOKEN indicates that the input token has a
      correct integrity check, but is a duplicate of a token already
      processed. This is a fatal error during context establishment.

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

   o  GSS_S_BAD_NAMETYPE indicates that the provided targ_name is
      of a type uninterpretable or unsupported by the applicable
      underlying GSS-API mechanism(s), so context establishment
      cannot be completed.

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

   o  GSS_S_BAD_MECH indicates receipt of a context establishment token
      or of a caller request specifying a mechanism unsupported by
      the local system or with the caller's active credentials

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

   This routine is used by a context initiator, and ordinarily emits one
   (or, for the case of a multi-step exchange, more than one)
   output_token suitable for use by the target within the selected
   mech_type's protocol. Using information in the credentials structure
   referenced by claimant_cred_handle, GSS_Init_sec_context()
   initializes the data structures required to establish a security
   context with target targ_name. The targ_name may be any valid
   INTERNAL NAME; it need not be an MN. The claimant_cred_handle must
   correspond to the same valid credentials structure on the initial
   call to GSS_Init_sec_context()  and on any successor calls resulting
   from GSS_S_CONTINUE_NEEDED status returns; different protocol



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   sequences modeled by the GSS_S_CONTINUE_NEEDED facility will require
   access to credentials at different points in the context
   establishment sequence.

   The input_context_handle argument is 0, specifying "not yet
   assigned", on the first GSS_Init_sec_context()  call relating to a
   given context. If successful (i.e., if accompanied by major_status
   GSS_S_COMPLETE or GSS_S_CONTINUE_NEEDED), and only if successful, the
   initial GSS_Init_sec_context() call returns a non-zero
   output_context_handle for use in future references to this context.
   Once a non-zero output_context_handle has been returned, GSS-API
   callers should call GSS_Delete_sec_context() to release context-
   related resources if errors occur in later phases of context
   establishment, or when an established context is no longer required.

   When continuation attempts to GSS_Init_sec_context() are needed to
   perform context establishment, the previously-returned non-zero
   handle value is entered into the input_context_handle argument and
   will be echoed in the returned output_context_handle argument. On
   such continuation attempts (and only on continuation attempts) the
   input_token value is used, to provide the token returned from the
   context's target.

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

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

   It is the caller's responsibility to establish a communications path
   to the target, and to transmit any returned output_token (independent
   of the accompanying returned major_status value) to the target over
   that path. The output_token can, however, be transmitted along with
   the first application-provided input message to be processed by
   GSS_GetMIC() or GSS_Wrap() in conjunction with a successfully-
   established context.

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



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   1.2.3 for more information on replay detection and sequencing
   features.)  The anon_req_flag requests that the initiator's identity
   not be transferred within tokens to be sent to the acceptor.

   Not all of the optionally-requestable features will be available in
   all underlying mech_types. The corresponding return state values
   deleg_state, mutual_state, replay_det_state, and sequence_state
   indicate, as a function of mech_type processing capabilities and
   initiator-provided input flags, the set of features which will be
   active on the context.  The returned trans_state value indicates
   whether the context is transferable to other processes through use of
   GSS_Export_sec_context().  These state indicators' values are
   undefined unless either the routine's major_status indicates
   GSS_S_COMPLETE, or TRUE prot_ready_state is returned along with
   GSS_S_CONTINUE_NEEDED major_status; for the latter case, it is
   possible that additional features, not confirmed or indicated along
   with TRUE prot_ready_state, will be confirmed and indicated when
   GSS_S_COMPLETE is subsequently returned.

   The returned anon_state and prot_ready_state values are significant
   for both GSS_S_COMPLETE and GSS_S_CONTINUE_NEEDED major_status
   returns from GSS_Init_sec_context().  When anon_state is returned
   TRUE, this indicates that neither the current token nor its
   predecessors delivers or has delivered the initiator's identity.
   Callers wishing to perform context establishment only if anonymity
   support is provided should transfer a returned token from
   GSS_Init_sec_context() to the peer only if it is accompanied by a
   TRUE anon_state indicator.  When prot_ready_state is returned TRUE in
   conjunction with GSS_S_CONTINUE_NEEDED major_status, this indicates
   that per-message protection operations may be applied on the context:
   see Section 1.2.7 for further discussion of this facility.

   Failure to provide the precise set of features requested by the
   caller does not cause context establishment to fail; it is the
   caller's prerogative to delete the context if the feature set
   provided is unsuitable for the caller's use.

   The returned mech_type value indicates the specific mechanism
   employed on the context, is valid only along with major_status
   GSS_S_COMPLETE, and will never indicate the value for "default".
   Note that, for the case of certain mechanisms which themselves
   perform negotiation, the returned mech_type result may indicate
   selection of a mechanism identified by an OID different than that
   passed in the input mech_type argument.

   The conf_avail return value indicates whether the context supports
   per-message confidentiality services, and so informs the caller
   whether or not a request for encryption through the conf_req_flag



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   input to GSS_Wrap()  can be honored. In similar fashion, the
   integ_avail return value indicates whether per-message integrity
   services are available (through either GSS_GetMIC() or GSS_Wrap()) on
   the established context. These state indicators' values are undefined
   unless either the routine's major_status indicates GSS_S_COMPLETE, or
   TRUE prot_ready_state is returned along with GSS_S_CONTINUE_NEEDED
   major_status.

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

   If the mutual_state is TRUE, this fact will be reflected within the
   output_token. A call to GSS_Accept_sec_context()  at the target in
   conjunction with such a context will return a token, to be processed
   by a continuation call to GSS_Init_sec_context(),  in order to
   achieve mutual authentication.

2.2.2:  GSS_Accept_sec_context call

   Inputs:

   o  acceptor_cred_handle CREDENTIAL HANDLE, -- NULL specifies
      "use default"

   o  input_context_handle CONTEXT HANDLE, -- 0 specifies
      "not yet assigned"

   o  chan_bindings OCTET STRING,

   o  input_token OCTET STRING

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  src_name INTERNAL NAME, -- guaranteed to be MN




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   o  mech_type OBJECT IDENTIFIER,

   o  output_context_handle CONTEXT HANDLE,

   o  deleg_state BOOLEAN,

   o  mutual_state BOOLEAN,

   o  replay_det_state BOOLEAN,

   o  sequence_state BOOLEAN,

   o  anon_state BOOLEAN,

   o  trans_state BOOLEAN,

   o  prot_ready_state BOOLEAN, -- see Section 1.2.7 for discussion

   o  conf_avail BOOLEAN,

   o  integ_avail BOOLEAN,

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

   o  delegated_cred_handle CREDENTIAL HANDLE,

   o  output_token OCTET STRING -NULL or token to pass to context
      initiator

   This call may block pending network interactions for those mech_types
   in which a directory service or other network entity must be
   consulted on behalf of a context acceptor in order to validate a
   received input_token.

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that context-level data structures
      were successfully initialized, and that per-message processing
      can now be performed in conjunction with this context.

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




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

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

   o  GSS_S_BAD_SIG indicates that the received input_token contains
      an incorrect integrity check, so context setup cannot be
      accomplished.

   o  GSS_S_DUPLICATE_TOKEN indicates that the integrity check on the
      received input_token was correct, but that the input_token
      was recognized as a duplicate of an input_token already
      processed. No new context is established.

   o  GSS_S_OLD_TOKEN indicates that the integrity check on the received
      input_token was correct, but that the input_token is too old
      to be checked for duplication against previously-processed
      input_tokens. No new context is established.

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

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

   o  GSS_S_BAD_BINDINGS indicates that a mismatch between the
      caller-provided chan_bindings and those extracted from the
      input_token was detected, signifying a security-relevant
      event and preventing context establishment.

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

   o  GSS_S_BAD_MECH indicates receipt of a context establishment token
      specifying a mechanism unsupported by the local system or with
      the caller's active credentials.





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

   The GSS_Accept_sec_context()  routine is used by a context target.
   Using information in the credentials structure referenced by the
   input acceptor_cred_handle, it verifies the incoming input_token and
   (following the successful completion of a context establishment
   sequence) returns the authenticated src_name and the mech_type used.
   The returned src_name is guaranteed to be an MN, processed by the
   mechanism under which the context was established. The
   acceptor_cred_handle must correspond to the same valid credentials
   structure on the initial call to GSS_Accept_sec_context() and on any
   successor calls resulting from GSS_S_CONTINUE_NEEDED status returns;
   different protocol sequences modeled by the GSS_S_CONTINUE_NEEDED
   mechanism will require access to credentials at different points in
   the context establishment sequence.

   The input_context_handle argument is 0, specifying "not yet
   assigned", on the first GSS_Accept_sec_context()  call relating to a
   given context.  If successful (i.e., if accompanied by major_status
   GSS_S_COMPLETE or GSS_S_CONTINUE_NEEDED), and only if successful, the
   initial GSS_Accept_sec_context() call returns a non-zero
   output_context_handle for use in future references to this context.
   Once a non-zero output_context_handle has been returned, GSS-API
   callers should call GSS_Delete_sec_context() to release context-
   related resources if errors occur in later phases of context
   establishment, or when an established context is no longer required.

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

   The returned state results (deleg_state, mutual_state,
   replay_det_state, sequence_state, anon_state, trans_state, and
   prot_ready_state) reflect the same information as described for
   GSS_Init_sec_context(), and their values are significant under the
   same return state conditions.











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   The conf_avail return value indicates whether the context supports
   per-message confidentiality services, and so informs the caller
   whether or not a request for encryption through the conf_req_flag
   input to GSS_Wrap()  can be honored. In similar fashion, the
   integ_avail return value indicates whether per-message integrity
   services are available (through either GSS_GetMIC()  or GSS_Wrap())
   on the established context.  These values are significant under the
   same return state conditions as described under
   GSS_Init_sec_context().

   The lifetime_rec return value is significant only in conjunction with
   GSS_S_COMPLETE major_status, and indicates the length of time for
   which the context will be valid, expressed as an offset from the
   present.

   The mech_type return value indicates the specific mechanism employed
   on the context, is valid only along with major_status GSS_S_COMPLETE,
   and will never indicate the value for "default".

   The delegated_cred_handle result is significant only when deleg_state
   is TRUE, and provides a means for the target to reference the
   delegated credentials. The output_token result, when non-NULL,
   provides a context-level token to be returned to the context
   initiator to continue a multi-step context establishment sequence. As
   noted with GSS_Init_sec_context(),  any returned token should be
   transferred to the context's peer (in this case, the context
   initiator), independent of the value of the accompanying returned
   major_status.

   Note: A target must be able to distinguish a context-level
   input_token, which is passed to GSS_Accept_sec_context(),  from the
   per-message data elements passed to GSS_VerifyMIC()  or GSS_Unwrap().
   These data elements may arrive in a single application message, and
   GSS_Accept_sec_context()  must be performed before per-message
   processing can be performed successfully.

2.2.3: GSS_Delete_sec_context call

   Input:

   o  context_handle CONTEXT HANDLE

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,




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   o  output_context_token OCTET STRING

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the context was recognized, and that
      relevant context-specific information was flushed.  If the caller
      provides a non-null buffer to receive an output_context_token, and
      the mechanism returns a non-NULL token into that buffer, the
      returned output_context_token is ready for transfer to the
      context's peer.

   o  GSS_S_NO_CONTEXT indicates that no valid context was recognized
      for the input context_handle provided, so no deletion was
      performed.

   o  GSS_S_FAILURE indicates that the context is recognized, but
      that the GSS_Delete_sec_context()  operation could not be
      performed for reasons unspecified at the GSS-API level.

   This call may block pending network interactions for mech_types in
   which active notification must be made to a central server when a
   security context is to be deleted.

   This call can be made by either peer in a security context, to flush
   context-specific information.  If a non-null output_context_token
   parameter is provided by the caller, an output_context_token may be
   returned to the caller.  If an output_context_token is provided to
   the caller, it can be passed to the context's peer to inform the
   peer's GSS-API implementation that the peer's corresponding context
   information can also be flushed. (Once a context is established, the
   peers involved are expected to retain cached credential and context-
   related information until the information's expiration time is
   reached or until a GSS_Delete_sec_context() call is made.)

   The facility for context_token usage to signal context deletion is
   retained for compatibility with GSS-API Version 1.  For current
   usage, it is recommended that both peers to a context invoke
   GSS_Delete_sec_context() independently, passing a null
   output_context_token buffer to indicate that no context_token is
   required.  Implementations of GSS_Delete_sec_context() should delete
   relevant locally-stored context information.

   Attempts to perform per-message processing on a deleted context will
   result in error returns.







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2.2.4:  GSS_Process_context_token call

   Inputs:

   o  context_handle CONTEXT HANDLE,

   o  input_context_token OCTET STRING

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the input_context_token was
      successfully processed in conjunction with the context
      referenced by context_handle.

   o  GSS_S_DEFECTIVE_TOKEN indicates that consistency checks
      performed on the received context_token failed, preventing
      further processing from being performed with that token.

   o  GSS_S_NO_CONTEXT indicates that no valid context was recognized
      for the input context_handle provided.

   o  GSS_S_FAILURE indicates that the context is recognized, but
      that the GSS_Process_context_token()  operation could not be
      performed for reasons unspecified at the GSS-API level.

   This call is used to process context_tokens received from a peer once
   a context has been established, with corresponding impact on
   context-level state information. One use for this facility is
   processing of the context_tokens generated by
   GSS_Delete_sec_context();  GSS_Process_context_token() will not block
   pending network interactions for that purpose. Another use is to
   process tokens indicating remote-peer context establishment failures
   after the point where the local GSS-API implementation has already
   indicated GSS_S_COMPLETE status.











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2.2.5:  GSS_Context_time call

   Input:

   o  context_handle CONTEXT HANDLE,

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

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

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the referenced context is valid,
      and will remain valid for the amount of time indicated in
      lifetime_rec.

   o  GSS_S_CONTEXT_EXPIRED indicates that data items related to the
      referenced context have expired.

   o  GSS_S_CREDENTIALS_EXPIRED indicates that the context is
      recognized, but that its associated credentials have expired.

   o  GSS_S_NO_CONTEXT indicates that no valid context was recognized
      for the input context_handle provided.

   o  GSS_S_FAILURE indicates that the requested operation failed for
       reasons unspecified at the GSS-API level.

   This call is used to determine the amount of time for which a
   currently established context will remain valid.

2.2.6:   GSS_Inquire_context call

   Input:

   o  context_handle CONTEXT HANDLE,

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,




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   o  src_name INTERNAL NAME,  -- name of context initiator,
                               -- guaranteed to be MN

   o  targ_name INTERNAL NAME,  -- name of context target,
                                -- guaranteed to be MN


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

   o  mech_type OBJECT IDENTIFIER, -- the mechanism supporting this
      security context

   o  deleg_state BOOLEAN,

   o  mutual_state BOOLEAN,

   o  replay_det_state BOOLEAN,

   o  sequence_state BOOLEAN,

   o  anon_state BOOLEAN,

   o  trans_state BOOLEAN,

   o  prot_ready_state BOOLEAN,

   o  conf_avail BOOLEAN,

   o  integ_avail BOOLEAN,

   o  locally_initiated BOOLEAN, -- TRUE if initiator, FALSE if acceptor

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the referenced context is valid
      and that src_name, targ_name, lifetime_rec, mech_type, deleg_state,
      mutual_state, replay_det_state, sequence_state, anon_state,
      trans_state, prot_ready_state, conf_avail, integ_avail, and
      locally_initiated return values describe the corresponding
      characteristics of the context.

   o  GSS_S_CONTEXT_EXPIRED indicates that the provided input
      context_handle is recognized, but that the referenced context
      has expired.  Return values other than major_status and
      minor_status are undefined.





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   o  GSS_S_NO_CONTEXT indicates that no valid context was recognized
      for the input context_handle provided. Return values other than
      major_status and minor_status are undefined.

   o  GSS_S_FAILURE indicates that the requested operation failed for
     reasons unspecified at the GSS-API level. Return values other than
         major_status and minor_status are undefined.

   This call is used to extract information describing characteristics
   of a security context.

2.2.7:   GSS_Wrap_size_limit call

   Inputs:

   o  context_handle CONTEXT HANDLE,

   o  qop INTEGER,

   o  output_size INTEGER

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  max_input_size INTEGER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates a successful token size determination:
   an input message with a length in octets equal to the
   returned max_input_size value will, when passed to GSS_Wrap()
   for processing on the context identified by the context_handle
   parameter and with the quality of protection specifier provided
   in the qop parameter, yield an output token no larger than the
   value of the provided output_size parameter.

   o  GSS_S_CONTEXT_EXPIRED indicates that the provided input
   context_handle is recognized, but that the referenced context
   has expired.  Return values other than major_status and
   minor_status are undefined.

   o  GSS_S_NO_CONTEXT indicates that no valid context was recognized
   for the input context_handle provided. Return values other than
   major_status and minor_status are undefined.




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   o  GSS_S_BAD_QOP indicates that the provided QOP value is not
   recognized or supported for the context.

   o  GSS_S_FAILURE indicates that the requested operation failed for
   reasons unspecified at the GSS-API level. Return values other than
   major_status and minor_status are undefined.

   This call is used to determine the largest input datum which may be
   passed to GSS_Wrap() without yielding an output token larger than a
   caller-specified value.

2.2.8:   GSS_Export_sec_context call

   Inputs:

   o  context_handle CONTEXT HANDLE

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  interprocess_token OCTET STRING

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the referenced context has been
   successfully exported to a representation in the interprocess_token,
   and is no longer available for use by the caller.

   o  GSS_S_UNAVAILABLE indicates that the context export facility
   is not available for use on the referenced context.  (This status
   should occur only for contexts for which the trans_state value is
   FALSE.) Return values other than major_status and minor_status are
   undefined.

   o GSS_S_CONTEXT_EXPIRED indicates that the provided input
   context_handle is recognized, but that the referenced context has
   expired.  Return values other than major_status and minor_status are
   undefined.

   o  GSS_S_NO_CONTEXT indicates that no valid context was recognized
   for the input context_handle provided. Return values other than
   major_status and minor_status are undefined.






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   o  GSS_S_FAILURE indicates that the requested operation failed for
   reasons unspecified at the GSS-API level. Return values other than
   major_status and minor_status are undefined.

   This call generates an interprocess token for transfer to another
   process within an end system, in order to transfer control of a
   security context to that process.  The recipient of the interprocess
   token will call GSS_Import_sec_context() to accept the transfer.  The
   GSS_Export_sec_context() operation is defined for use only with
   security contexts which are fully and successfully established (i.e.,
   those for which GSS_Init_sec_context() and GSS_Accept_sec_context()
   have returned GSS_S_COMPLETE major_status).

   To ensure portability, a caller of GSS_Export_sec_context() must not
   assume that a context may continue to be used once it has been
   exported; following export, the context referenced by the
   context_handle cannot be assumed to remain valid.  Further, portable
   callers must not assume that a given interprocess token can be
   imported by GSS_Import_sec_context() more than once, thereby creating
   multiple instantiations of a single context.  GSS-API implementations
   may detect and reject attempted multiple imports, but are not
   required to do so.

   The internal representation contained within the interprocess token
   is an implementation-defined local matter.  Interprocess tokens
   cannot be assumed to be transferable across different GSS-API
   implementations.

   It is recommended that GSS-API implementations adopt policies suited
   to their operational environments in order to define the set of
   processes eligible to import a context, but specific constraints in
   this area are local matters.  Candidate examples include transfers
   between processes operating on behalf of the same user identity, or
   processes comprising a common job.  However, it may be impossible to
   enforce such policies in some implementations.

   In support of the above goals, implementations may protect the
   transferred context data by using cryptography to protect data within
   the interprocess token, or by using interprocess tokens as a means to
   reference local interprocess communication facilities (protected by
   other means) rather than storing the context data directly within the
   tokens.

   Transfer of an open context may, for certain mechanisms and
   implementations, reveal data about the credential which was used to
   establish the context.  Callers should, therefore, be cautious about
   the trustworthiness of processes to which they transfer contexts.
   Although the GSS-API implementation may provide its own set of



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   protections over the exported context, the caller is responsible for
   protecting the interprocess token from disclosure, and for taking
   care that the context is transferred to an appropriate destination
   process.

2.2.9:   GSS_Import_sec_context call

   Inputs:

   o  interprocess_token OCTET STRING

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  context_handle CONTEXT HANDLE

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the context represented by the
   input interprocess_token has been successfully transferred to
   the caller, and is available for future use via the output
   context_handle.

   o  GSS_S_CONTEXT_EXPIRED indicates that the context represented by
   the input interprocess_token has expired. Return values other
   than major_status and minor_status are undefined.

   o  GSS_S_NO_CONTEXT indicates that the context represented by the
   input interprocess_token was invalid. Return values other than
   major_status and minor_status are undefined.

   o  GSS_S_DEFECTIVE_TOKEN indicates that the input interprocess_token
   was defective.  Return values other than major_status and
   minor_status are undefined.

   o  GSS_S_UNAVAILABLE indicates that the context import facility
   is not available for use on the referenced context.  Return values
   other than major_status and minor_status are undefined.

   o  GSS_S_UNAUTHORIZED indicates that the context represented by
   the input interprocess_token is unauthorized for transfer to the
   caller. Return values other than major_status and minor_status
   are undefined.





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   o  GSS_S_FAILURE indicates that the requested operation failed for
   reasons unspecified at the GSS-API level. Return values other than
   major_status and minor_status are undefined.

   This call processes an interprocess token generated by
   GSS_Export_sec_context(), making the transferred context available
   for use by the caller.  After a successful GSS_Import_sec_context()
   operation, the imported context is available for use by the importing
   process.

   For further discussion of the security and authorization issues
   regarding this call, please see the discussion in Section 2.2.8.

2.3:  Per-message calls

   This group of calls is used to perform per-message protection
   processing on an established security context. None of these calls
   block pending network interactions. These calls may be invoked by a
   context's initiator or by the context's target.  The four members of
   this group should be considered as two pairs; the output from
   GSS_GetMIC()  is properly input to GSS_VerifyMIC(),  and the output
   from GSS_Wrap() is properly input to GSS_Unwrap().

   GSS_GetMIC() and GSS_VerifyMIC() support data origin authentication
   and data integrity services. When GSS_GetMIC()  is invoked on an
   input message, it yields a per-message token containing data items
   which allow underlying mechanisms to provide the specified security
   services. The original message, along with the generated per-message
   token, is passed to the remote peer; these two data elements are
   processed by GSS_VerifyMIC(),  which validates the message in
   conjunction with the separate token.

   GSS_Wrap() and GSS_Unwrap() support caller-requested confidentiality
   in addition to the data origin authentication and data integrity
   services offered by GSS_GetMIC()  and GSS_VerifyMIC(). GSS_Wrap()
   outputs a single data element, encapsulating optionally enciphered
   user data as well as associated token data items.  The data element
   output from GSS_Wrap()  is passed to the remote peer and processed by
   GSS_Unwrap()  at that system. GSS_Unwrap() combines decipherment (as
   required) with validation of data items related to authentication and
   integrity.










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2.3.1:  GSS_GetMIC call

   Note: This call is functionally equivalent to the GSS_Sign call as
   defined in previous versions of this specification. In the interests
   of backward compatibility, it is recommended that implementations
   support this function under both names for the present; future
   references to this function as GSS_Sign are deprecated.

   Inputs:

   o  context_handle CONTEXT HANDLE,

   o  qop_req INTEGER,-0 specifies default QOP

   o  message OCTET STRING

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  per_msg_token OCTET STRING

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that an integrity check, suitable for an
      established security context, was successfully applied and
      that the message and corresponding per_msg_token are ready
      for transmission.

   o  GSS_S_CONTEXT_EXPIRED indicates that context-related data
      items have expired, so that the requested operation cannot be
      performed.

   o  GSS_S_CREDENTIALS_EXPIRED indicates that the context is recognized,
      but that its associated credentials have expired, so
      that the requested operation cannot be performed.

   o  GSS_S_NO_CONTEXT indicates that no valid context was recognized
      for the input context_handle provided.

   o  GSS_S_BAD_QOP indicates that the provided QOP value is not
      recognized or supported for the context.

   o  GSS_S_FAILURE indicates that the context is recognized, but
      that the requested operation could not be performed for
      reasons unspecified at the GSS-API level.



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   Using the security context referenced by context_handle, apply an
   integrity check to the input message (along with timestamps and/or
   other data included in support of mech_type-specific mechanisms) and
   return the result in per_msg_token. The qop_req parameter,
   interpretation of which is discussed in Section 1.2.4, allows
   quality-of-protection control. The caller passes the message and the
   per_msg_token to the target.

   The GSS_GetMIC()  function completes before the message and
   per_msg_token is sent to the peer; successful application of
   GSS_GetMIC()  does not guarantee that a corresponding GSS_VerifyMIC()
   has been (or can necessarily be) performed successfully when the
   message arrives at the destination.

   Mechanisms which do not support per-message protection services
   should return GSS_S_FAILURE if this routine is called.

2.3.2:  GSS_VerifyMIC call

   Note: This call is functionally equivalent to the GSS_Verify call as
   defined in previous versions of this specification. In the interests
   of backward compatibility, it is recommended that implementations
   support this function under both names for the present; future
   references to this function as GSS_Verify are deprecated.

   Inputs:

   o  context_handle CONTEXT HANDLE,

   o  message OCTET STRING,

   o  per_msg_token OCTET STRING

   Outputs:

   o  qop_state INTEGER,

   o  major_status INTEGER,

   o  minor_status INTEGER,

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the message was successfully
      verified.






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   o  GSS_S_DEFECTIVE_TOKEN indicates that consistency checks performed
      on the received per_msg_token failed, preventing
      further processing from being performed with that token.

   o  GSS_S_BAD_SIG indicates that the received per_msg_token contains
      an incorrect integrity check for the message.

   o  GSS_S_DUPLICATE_TOKEN, GSS_S_OLD_TOKEN, GSS_S_UNSEQ_TOKEN,
      and GSS_S_GAP_TOKEN values appear in conjunction with the
      optional per-message replay detection features described
      in Section 1.2.3; their semantics are described in that section.

   o  GSS_S_CONTEXT_EXPIRED indicates that context-related data
      items have expired, so that the requested operation cannot be
      performed.

   o  GSS_S_CREDENTIALS_EXPIRED indicates that the context is
   recognized,
      but that its associated credentials have expired, so
      that the requested operation cannot be performed.

   o  GSS_S_NO_CONTEXT indicates that no valid context was recognized
      for the input context_handle provided.

   o  GSS_S_FAILURE indicates that the context is recognized, but
      that the GSS_VerifyMIC() operation could not be performed for
      reasons unspecified at the GSS-API level.

   Using the security context referenced by context_handle, verify that
   the input per_msg_token contains an appropriate integrity check for
   the input message, and apply any active replay detection or
   sequencing features. Return an indication of the quality-of-
   protection applied to the processed message in the qop_state result.
   Since the GSS_VerifyMIC() routine never provides a confidentiality
   service, its implementations should not return non-zero values in the
   confidentiality fields of the output qop_state.

   Mechanisms which do not support per-message protection services
   should return GSS_S_FAILURE if this routine is called.

2.3.3: GSS_Wrap call

   Note: This call is functionally equivalent to the GSS_Seal call as
   defined in previous versions of this specification. In the interests
   of backward compatibility, it is recommended that implementations
   support this function under both names for the present; future
   references to this function as GSS_Seal are deprecated.




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   Inputs:

   o  context_handle CONTEXT HANDLE,

   o  conf_req_flag BOOLEAN,

   o  qop_req INTEGER,-0 specifies default QOP

   o  input_message OCTET STRING

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  conf_state BOOLEAN,

   o  output_message OCTET STRING

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the input_message was successfully
      processed and that the output_message is ready for
      transmission.

   o  GSS_S_CONTEXT_EXPIRED indicates that context-related data
      items have expired, so that the requested operation cannot be
      performed.

   o  GSS_S_CREDENTIALS_EXPIRED indicates that the context is
   recognized,
      but that its associated credentials have expired, so
      that the requested operation cannot be performed.

   o  GSS_S_NO_CONTEXT indicates that no valid context was recognized
      for the input context_handle provided.

   o  GSS_S_BAD_QOP indicates that the provided QOP value is not
      recognized or supported for the context.

   o  GSS_S_FAILURE indicates that the context is recognized, but
      that the GSS_Wrap()  operation could not be performed for
      reasons unspecified at the GSS-API level.

   Performs the data origin authentication and data integrity functions
   of GSS_GetMIC().  If the input conf_req_flag is TRUE, requests that
   confidentiality be applied to the input_message.  Confidentiality may



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   not be supported in all mech_types or by all implementations; the
   returned conf_state flag indicates whether confidentiality was
   provided for the input_message. The qop_req parameter, interpretation
   of which is discussed in Section 1.2.4, allows quality-of-protection
   control.

   In all cases, the GSS_Wrap()  call yields a single output_message
   data element containing (optionally enciphered) user data as well as
   control information.

   Mechanisms which do not support per-message protection services
   should return GSS_S_FAILURE if this routine is called.

2.3.4: GSS_Unwrap call

   Note: This call is functionally equivalent to the GSS_Unseal call as
   defined in previous versions of this specification. In the interests
   of backward compatibility, it is recommended that implementations
   support this function under both names for the present; future
   references to this function as GSS_Unseal are deprecated.

   Inputs:

   o  context_handle CONTEXT HANDLE,

   o  input_message OCTET STRING

   Outputs:

   o  conf_state BOOLEAN,

   o  qop_state INTEGER,

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  output_message OCTET STRING

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the input_message was
      successfully processed and that the resulting output_message is
      available.

   o  GSS_S_DEFECTIVE_TOKEN indicates that consistency checks performed
      on the per_msg_token extracted from the input_message
      failed, preventing further processing from being performed.



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   o  GSS_S_BAD_SIG indicates that an incorrect integrity check was
   detected
      for the message.

   o  GSS_S_DUPLICATE_TOKEN, GSS_S_OLD_TOKEN, GSS_S_UNSEQ_TOKEN,
      and GSS_S_GAP_TOKEN values appear in conjunction with the
      optional per-message replay detection features described
      in Section 1.2.3; their semantics are described in that section.

   o  GSS_S_CONTEXT_EXPIRED indicates that context-related data
      items have expired, so that the requested operation cannot be
      performed.

   o  GSS_S_CREDENTIALS_EXPIRED indicates that the context is
   recognized,
      but that its associated credentials have expired, so
      that the requested operation cannot be performed.

   o  GSS_S_NO_CONTEXT indicates that no valid context was recognized
      for the input context_handle provided.

   o  GSS_S_FAILURE indicates that the context is recognized, but
      that the GSS_Unwrap()  operation could not be performed for
      reasons unspecified at the GSS-API level.

   Processes a data element generated (and optionally enciphered) by
   GSS_Wrap(),  provided as input_message. The returned conf_state value
   indicates whether confidentiality was applied to the input_message.
   If conf_state is TRUE, GSS_Unwrap()  deciphers the input_message.
   Returns an indication of the quality-of-protection applied to the
   processed message in the qop_state result. GSS_Wrap()  performs the
   data integrity and data origin authentication checking functions of
   GSS_VerifyMIC()  on the plaintext data. Plaintext data is returned in
   output_message.

   Mechanisms which do not support per-message protection services
   should return GSS_S_FAILURE if this routine is called.

2.4:  Support calls

   This group of calls provides support functions useful to GSS-API
   callers, independent of the state of established contexts. Their
   characterization with regard to blocking or non-blocking status in
   terms of network interactions is unspecified.







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2.4.1:  GSS_Display_status call

   Inputs:

   o  status_value INTEGER,-GSS-API major_status or minor_status
      return value

   o  status_type INTEGER,-1 if major_status, 2 if minor_status

   o  mech_type OBJECT IDENTIFIER-mech_type to be used for minor_
      status translation

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  status_string_set SET OF OCTET STRING

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that a valid printable status
      representation (possibly representing more than one status event
      encoded within the status_value) is available in the returned
      status_string_set.

   o  GSS_S_BAD_MECH indicates that translation in accordance with an
      unsupported mech_type was requested, so translation could not
      be performed.

   o  GSS_S_BAD_STATUS indicates that the input status_value was
      invalid, or that the input status_type carried a value other
      than 1 or 2, so translation could not be performed.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.

   Provides a means for callers to translate GSS-API-returned major and
   minor status codes into printable string representations.

2.4.2:  GSS_Indicate_mechs call

   Input:

   o  (none)





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   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  mech_set SET OF OBJECT IDENTIFIER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that a set of available mechanisms has
      been returned in mech_set.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.

   Allows callers to determine the set of mechanism types available on
   the local system. This call is intended for support of specialized
   callers who need to request non-default mech_type sets from
   GSS_Acquire_cred(),  and should not be needed by other callers.

2.4.3:  GSS_Compare_name call

   Inputs:

   o  name1 INTERNAL NAME,

   o  name2 INTERNAL NAME

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  name_equal BOOLEAN

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that name1 and name2 were comparable,
      and that the name_equal result indicates whether name1 and
      name2 represent the same entity.

   o  GSS_S_BAD_NAMETYPE indicates that one or both of name1 and
      name2 contained internal type specifiers uninterpretable
      by the applicable underlying GSS-API mechanism(s), or that
      the two names' types are different and incomparable, so that
      the comparison operation could not be completed.



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   o  GSS_S_BAD_NAME indicates that one or both of the input names
      was ill-formed in terms of its internal type specifier, so
      the comparison operation could not be completed.

   o  GSS_S_FAILURE indicates that the call's operation could not
      be performed for reasons unspecified at the GSS-API level.

   Allows callers to compare two internal name representations to
   determine whether they refer to the same entity.  If either name
   presented to GSS_Compare_name() denotes an anonymous principal,
   GSS_Compare_name() shall indicate FALSE.  It is not required that
   either or both inputs name1 and name2 be MNs; for some
   implementations and cases, GSS_S_BAD_NAMETYPE may be returned,
   indicating name incomparability, for the case where neither input
   name is an MN.

2.4.4:  GSS_Display_name call

   Inputs:

   o  name INTERNAL NAME

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  name_string OCTET STRING,

   o  name_type OBJECT IDENTIFIER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that a valid printable name
      representation is available in the returned name_string.

   o  GSS_S_BAD_NAMETYPE indicates that the provided name was of a
      type uninterpretable by the applicable underlying GSS-API
      mechanism(s), so no printable representation could be generated.

   o  GSS_S_BAD_NAME indicates that the contents of the provided name
      were inconsistent with the internally-indicated name type, so
      no printable representation could be generated.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.




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   Allows callers to translate an internal name representation into a
   printable form with associated namespace type descriptor. The syntax
   of the printable form is a local matter.

   If the input name represents an anonymous identity, a reserved value
   (GSS_C_NT_ANONYMOUS) shall be returned for name_type.

2.4.5:  GSS_Import_name call

   Inputs:

   o  input_name_string OCTET STRING,

   o  input_name_type OBJECT IDENTIFIER

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  output_name INTERNAL NAME

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that a valid name representation is
      output in output_name and described by the type value in
      output_name_type.

   o  GSS_S_BAD_NAMETYPE indicates that the input_name_type is unsupported
      by the applicable underlying GSS-API mechanism(s), so the import
      operation could not be completed.

   o  GSS_S_BAD_NAME indicates that the provided input_name_string
      is ill-formed in terms of the input_name_type, so the import
      operation could not be completed.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.

   Allows callers to provide a name representation as a contiguous octet
   string, designate the type of namespace in conjunction with which it
   should be parsed, and convert that representation to an internal form
   suitable for input to other GSS-API routines.  The syntax of the
   input_name_string is defined in conjunction with its associated name
   type; depending on the input_name_type, the associated
   input_name_string may or may not be a printable string. Note: The
   input_name_type argument serves to describe and qualify the



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   interpretation of the associated input_name_string; it does not
   specify the data type of the returned output_name.

   If a mechanism claims support for a particular name type, its
   GSS_Import_name() operation shall be able to accept all possible
   values conformant to the external name syntax as defined for that
   name type.  These imported values may correspond to:

      (1) locally registered entities (for which credentials may be
      acquired),

      (2) non-local entities (for which local credentials cannot be
      acquired, but which may be referenced as targets of initiated
      security contexts or initiators of accepted security contexts), or
      to

      (3) neither of the above.

   Determination of whether a particular name belongs to class (1), (2),
   or (3) as described above is not guaranteed to be performed by the
   GSS_Import_name() function.

   The internal name generated by a GSS_Import_name() operation may be a
   single-mechanism MN, and is likely to be an MN within a single-
   mechanism implementation, but portable callers must not depend on
   this property (and must not, therefore, assume that the output from
   GSS_Import_name() can be passed directly to GSS_Export_name() without
   first being processed through GSS_Canonicalize_name()).

2.4.6: GSS_Release_name call

   Inputs:

   o  name INTERNAL NAME

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the storage associated with the
      input name was successfully released.

   o  GSS_S_BAD_NAME indicates that the input name argument did not
      contain a valid name.



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   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.

   Allows callers to release the storage associated with an internal
   name representation.  This call's specific behavior depends on the
   language and programming environment within which a GSS-API
   implementation operates, and is therefore detailed within applicable
   bindings specifications; in particular, this call may be superfluous
   within bindings where memory management is automatic.

2.4.7: GSS_Release_buffer call

   Inputs:

   o  buffer OCTET STRING

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the storage associated with the
      input buffer was successfully released.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.

   Allows callers to release the storage associated with an OCTET STRING
   buffer allocated by another GSS-API call.  This call's specific
   behavior depends on the language and programming environment within
   which a GSS-API implementation operates, and is therefore detailed
   within applicable bindings specifications; in particular, this call
   may be superfluous within bindings where memory management is
   automatic.

2.4.8: GSS_Release_OID_set call

   Inputs:

   o  buffer SET OF OBJECT IDENTIFIER

   Outputs:

   o  major_status INTEGER,




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   o  minor_status INTEGER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the storage associated with the
      input object identifier set was successfully released.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.

   Allows callers to release the storage associated with an object
   identifier set object allocated by another GSS-API call.  This call's
   specific behavior depends on the language and programming environment
   within which a GSS-API implementation operates, and is therefore
   detailed within applicable bindings specifications; in particular,
   this call may be superfluous within bindings where memory management
   is automatic.

2.4.9: GSS_Create_empty_OID_set call

   Inputs:

   o  (none)

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  oid_set SET OF OBJECT IDENTIFIER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates successful completion

   o  GSS_S_FAILURE indicates that the operation failed

   Creates an object identifier set containing no object identifiers, to
   which members may be subsequently added using the
   GSS_Add_OID_set_member() routine.  These routines are intended to be
   used to construct sets of mechanism object identifiers, for input to
   GSS_Acquire_cred().








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2.4.10: GSS_Add_OID_set_member call

   Inputs:

   o  member_oid OBJECT IDENTIFIER,

   o  oid_set SET OF OBJECT IDENTIFIER

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   Return major_status codes:

   o  GSS_S_COMPLETE indicates successful completion

   o  GSS_S_FAILURE indicates that the operation failed

   Adds an Object Identifier to an Object Identifier set.  This routine
   is intended for use in conjunction with GSS_Create_empty_OID_set()
   when constructing a set of mechanism OIDs for input to
   GSS_Acquire_cred().

2.4.11: GSS_Test_OID_set_member call

   Inputs:

   o  member OBJECT IDENTIFIER,

   o  set SET OF OBJECT IDENTIFIER

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  present BOOLEAN

   Return major_status codes:

   o  GSS_S_COMPLETE indicates successful completion

   o  GSS_S_FAILURE indicates that the operation failed





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   Interrogates an Object Identifier set to determine whether a
   specified Object Identifier is a member.  This routine is intended to
   be used with OID sets returned by GSS_Indicate_mechs(),
   GSS_Acquire_cred(), and GSS_Inquire_cred().

2.4.12: GSS_Release_OID call

   Inputs:

   o  oid OBJECT IDENTIFIER

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates successful completion

   o  GSS_S_FAILURE indicates that the operation failed

   Allows the caller to release the storage associated with an OBJECT
   IDENTIFIER buffer allocated by another GSS-API call. This call's
   specific behavior depends on the language and programming environment
   within which a GSS-API implementation operates, and is therefore
   detailed within applicable bindings specifications; in particular,
   this call may be superfluous within bindings where memory management
   is automatic.

2.4.13: GSS_OID_to_str call

   Inputs:

   o  oid OBJECT IDENTIFIER

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  oid_str OCTET STRING

   Return major_status codes:

   o  GSS_S_COMPLETE indicates successful completion



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   o  GSS_S_FAILURE indicates that the operation failed

   The function GSS_OID_to_str() returns a string representing the input
   OID in numeric ASN.1 syntax format (curly-brace enclosed, space-
   delimited, e.g., "{2 16 840 1 113687 1 2 1}"). The string is
   releasable using GSS_Release_buffer(). If the input "oid" does not
   represent a syntactically valid object identifier, GSS_S_FAILURE
   status is returned and the returned oid_str result is NULL.

2.4.14: GSS_Str_to_OID call

   Inputs:

   o  oid_str OCTET STRING

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  oid OBJECT IDENTIFIER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates successful completion

   o  GSS_S_FAILURE indicates that the operation failed

   The function GSS_Str_to_OID() constructs and returns an OID from its
   printable form; implementations should be able to accept the numeric
   ASN.1 syntax form as described for GSS_OID_to_str(), and this form
   should be used for portability, but implementations of this routine
   may also accept other formats (e.g., "1.2.3.3"). The OID is suitable
   for release using the function GSS_Release_OID(). If the input
   oid_str cannot be translated into an OID, GSS_S_FAILURE status is
   returned and the "oid" result is NULL.

2.4.15:  GSS_Inquire_names_for_mech call

   Input:

   o  input_mech_type OBJECT IDENTIFIER, -- mechanism type

   Outputs:

   o  major_status INTEGER,




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   o  minor_status INTEGER,

   o  name_type_set SET OF OBJECT IDENTIFIER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that the output name_type_set contains
      a list of name types which are supported by the locally available
      mechanism identified by input_mech_type.

   o  GSS_S_BAD_MECH indicates that the mechanism identified by
      input_mech_type was unsupported within the local implementation,
      causing the query to fail.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.

   Allows callers to determine the set of name types which are
   supportable by a specific locally-available mechanism.

2.4.16: GSS_Inquire_mechs_for_name call

   Inputs:

   o  input_name INTERNAL NAME,

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  mech_types SET OF OBJECT IDENTIFIER

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that a set of object identifiers,
      corresponding to the set of mechanisms suitable for processing
      the input_name, is available in mech_types.

   o  GSS_S_BAD_NAME indicates that the input_name could not be
      processed.

   o  GSS_S_BAD_NAMETYPE indicates that the type of the input_name
      is unsupported by the GSS-API implementation.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.



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   This routine returns the mechanism set with which the input_name may
   be processed.  After use, the mech_types object should be freed by
   the caller via the GSS_Release_OID_set() call.  Note: it is
   anticipated that implementations of GSS_Inquire_mechs_for_name() will
   commonly operate based on type information describing the
   capabilities of available mechanisms; it is not guaranteed that all
   identified mechanisms will necessarily be able to canonicalize (via
   GSS_Canonicalize_name()) a particular name.

2.4.17: GSS_Canonicalize_name call

   Inputs:

   o  input_name INTERNAL NAME,

   o  mech_type OBJECT IDENTIFIER  -- must be explicit mechanism,
                                      not "default" specifier

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  output_name INTERNAL NAME

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that a mechanism-specific reduction of
      the input_name, as processed by the mechanism identified by
      mech_type, is available in output_name.

   o  GSS_S_BAD_MECH indicates that the identified mechanism is
      unsupported.

   o  GSS_S_BAD_NAMETYPE indicates that the input name does not
      contain an element with suitable type for processing by the
      identified mechanism.

   o  GSS_S_BAD_NAME indicates that the input name contains an
      element with suitable type for processing by the identified
      mechanism, but that this element could not be processed
      successfully.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.





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   This routine reduces a GSS-API internal name, which may in general
   contain elements corresponding to multiple mechanisms, to a
   mechanism-specific Mechanism Name (MN) by applying the translations
   corresponding to the mechanism identified by mech_type.

2.4.18: GSS_Export_name call

   Inputs:

   o  input_name INTERNAL NAME, -- required to be MN

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  output_name OCTET STRING

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that a flat representation of the
      input name is available in output_name.

   o  GSS_S_NAME_NOT_MN indicates that the input name contained
      elements corresponding to multiple mechanisms, so cannot
      be exported into a single-mechanism flat form.

   o  GSS_S_BAD_NAME indicates that the input name was an MN,
      but could not be processed.

   o  GSS_S_BAD_NAMETYPE indicates that the input name was an MN,
      but that its type is unsupported by the GSS-API implementation.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.

   This routine creates a flat name representation, suitable for
   bytewise comparison or for input to GSS_Import_name() in conjunction
   with the reserved GSS-API Exported Name Object OID, from a internal-
   form Mechanism Name (MN) as emitted, e.g., by GSS_Canonicalize_name()
   or GSS_Accept_sec_context().

   The emitted GSS-API Exported Name Object is self-describing; no
   associated parameter-level OID need be emitted by this call.  This
   flat representation consists of a mechanism-independent wrapper
   layer, defined in Section 3.2 of this document, enclosing a
   mechanism-defined name representation.



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   In all cases, the flat name output by GSS_Export_name() to correspond
   to a particular input MN must be invariant over time within a
   particular installation.

   The GSS_S_NAME_NOT_MN status code is provided to enable
   implementations to reject input names which are not MNs.  It is not,
   however, required for purposes of conformance to this specification
   that all non-MN input names must necessarily be rejected.

2.4.19: GSS_Duplicate_name call

   Inputs:

   o  src_name INTERNAL NAME

   Outputs:

   o  major_status INTEGER,

   o  minor_status INTEGER,

   o  dest_name INTERNAL NAME

   Return major_status codes:

   o  GSS_S_COMPLETE indicates that dest_name references an internal
      name object containing the same name as passed to src_name.

   o  GSS_S_BAD_NAME indicates that the input name was invalid.

   o  GSS_S_BAD_NAMETYPE indicates that the input name's type
      is unsupported by the GSS-API implementation.

   o  GSS_S_FAILURE indicates that the requested operation could not
      be performed for reasons unspecified at the GSS-API level.

   This routine takes input internal name src_name, and returns another
   reference (dest_name) to that name which can be used even if src_name
   is later freed.  (Note: This may be implemented by copying or through
   use of reference counts.)

3: Data Structure Definitions for GSS-V2 Usage

   Subsections of this section define, for interoperability and
   portability purposes, certain data structures for use with GSS-V2.






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3.1: Mechanism-Independent Token Format

   This section specifies a mechanism-independent level of encapsulating
   representation for the initial token of a GSS-API context
   establishment sequence, incorporating an identifier of the mechanism
   type to be used on that context and enabling tokens to be interpreted
   unambiguously at GSS-API peers. Use of this format is required for
   initial context establishment tokens of Internet standards-track
   GSS-API mechanisms; use in non-initial tokens is optional.

   The encoding format for the token tag is derived from ASN.1 and DER
   (per illustrative ASN.1 syntax included later within this
   subsection), but its concrete representation is defined directly in
   terms of octets rather than at the ASN.1 level in order to facilitate
   interoperable implementation without use of general ASN.1 processing
   code.  The token tag consists of the following elements, in order:

      1. 0x60 -- Tag for [APPLICATION 0] SEQUENCE; indicates that
      constructed form, definite length encoding follows.

      2. Token length octets, specifying length of subsequent data
      (i.e., the summed lengths of elements 3-5 in this list, and of the
      mechanism-defined token object following the tag).  This element
      comprises a variable number of octets:

      2a. If the indicated value is less than 128, it shall be
      represented in a single octet with bit 8 (high order) set to "0"
      and the remaining bits representing the value.

      2b. If the indicated value is 128 or more, it shall be represented
      in two or more octets, with bit 8 of the first octet set to "1"
      and the remaining bits of the first octet specifying the number of
      additional octets.  The subsequent octets carry the value, 8 bits
      per octet, most significant digit first.  The minimum number of
      octets shall be used to encode the length (i.e., no octets
      representing leading zeros shall be included within the length
      encoding).

      3. 0x06 -- Tag for OBJECT IDENTIFIER

      4. Object identifier length -- length (number of octets) of the
      encoded object identifier contained in element 5, encoded per
      rules as described in 2a. and 2b. above.

      5. Object identifier octets -- variable number of octets, encoded
      per ASN.1 BER rules:





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      5a. The first octet contains the sum of two values: (1) the top-
      level object identifier component, multiplied by 40 (decimal), and
      (2) the second-level object identifier component.  This special
      case is the only point within an object identifier encoding where
      a single octet represents contents of more than one component.

      5b. Subsequent octets, if required, encode successively-lower
      components in the represented object identifier.  A component's
      encoding may span multiple octets, encoding 7 bits per octet (most
      significant bits first) and with bit 8 set to "1" on all but the
      final octet in the component's encoding.  The minimum number of
      octets shall be used to encode each component (i.e., no octets
      representing leading zeros shall be included within a component's
      encoding).

      (Note: In many implementations, elements 3-5 may be stored and
      referenced as a contiguous string constant.)

   The token tag is immediately followed by a mechanism-defined token
   object.  Note that no independent size specifier intervenes following
   the object identifier value to indicate the size of the mechanism-
   defined token object.  While ASN.1 usage within mechanism-defined
   tokens is permitted, there is no requirement that the mechanism-
   specific innerContextToken, innerMsgToken, and sealedUserData data
   elements must employ ASN.1 BER/DER encoding conventions.


























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   The following ASN.1 syntax is included for descriptive purposes only,
   to illustrate structural relationships among token and tag objects.
   For interoperability purposes, token and tag encoding shall be
   performed using the concrete encoding procedures described earlier in
   this subsection.

       GSS-API DEFINITIONS ::=

       BEGIN

       MechType ::= OBJECT IDENTIFIER
       -- data structure definitions

       -- callers must be able to distinguish among
       -- InitialContextToken, SubsequentContextToken,
       -- PerMsgToken, and SealedMessage data elements
       -- based on the usage in which they occur

       InitialContextToken ::=
       -- option indication (delegation, etc.) indicated within
       -- mechanism-specific token
       [APPLICATION 0] IMPLICIT SEQUENCE {
               thisMech MechType,
               innerContextToken ANY DEFINED BY thisMech
                  -- contents mechanism-specific
                  -- ASN.1 structure not required
               }

       SubsequentContextToken ::= innerContextToken ANY
       -- interpretation based on predecessor InitialContextToken
       -- ASN.1 structure not required

       PerMsgToken ::=
       -- as emitted by GSS_GetMIC and processed by GSS_VerifyMIC
       -- ASN.1 structure not required
               innerMsgToken ANY

       SealedMessage ::=
       -- as emitted by GSS_Wrap and processed by GSS_Unwrap
       -- includes internal, mechanism-defined indicator
       -- of whether or not encrypted
       -- ASN.1 structure not required
               sealedUserData ANY

       END






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3.2: Mechanism-Independent Exported Name Object Format

   This section specifies a mechanism-independent level of encapsulating
   representation for names exported via the GSS_Export_name() call,
   including an object identifier representing the exporting mechanism.
   The format of names encapsulated via this representation shall be
   defined within individual mechanism drafts.  Name objects of this
   type will be identified with the following Object Identifier:

   {1(iso), 3(org), 6(dod), 1(internet), 5(security), 6(nametypes),
   4(gss-api-exported-name)}

   No name type OID is included in this mechanism-independent level of
   format definition, since (depending on individual mechanism
   specifications) the enclosed name may be implicitly typed or may be
   explicitly typed using a means other than OID encoding.

        Length    Name          Description

        2               TOK_ID          Token Identifier
                                        For exported name objects, this
                                        must be hex 04 01.
        2               MECH_OID_LEN    Length of the Mechanism OID
        MECH_OID_LEN    MECH_OID        Mechanism OID, in DER
        4               NAME_LEN        Length of name
        NAME_LEN        NAME            Exported name; format defined in
                                        applicable mechanism draft.

4: Name Type Definitions

   This section includes definitions for name types and associated
   syntaxes which are defined in a mechanism-independent fashion at the
   GSS-API level rather than being defined in individual mechanism
   specifications.

4.1: Host-Based Service Name Form

   The following Object Identifier value is provided as a means to
   identify this name form:

   {1(iso), 3(org), 6(dod), 1(internet), 5(security), 6(nametypes),
   2(gss-host-based-services)}

   The recommended symbolic name for this type is
   "GSS_C_NT_HOSTBASED_SERVICE".






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   This name type is used to represent services associated with host
   computers.  This name form is constructed using two elements,
   "service" and "hostname", as follows:

                             service@hostname

   When a reference to a name of this type is resolved, the "hostname"
   is canonicalized by attempting a DNS lookup and using the fully-
   qualified domain name which is returned, or by using the "hostname"
   as provided if the DNS lookup fails.  The canonicalization operation
   also maps the host's name into lower-case characters.

   The "hostname" element may be omitted. If no "@" separator is
   included, the entire name is interpreted as the service specifier,
   with the "hostname" defaulted to the canonicalized name of the local
   host.

   Values for the "service" element are registered with the IANA.

4.2: User Name Form

   This name form shall be represented by the Object Identifier {iso(1)
   member-body(2) United States(840) mit(113554) infosys(1) gssapi(2)
   generic(1) user_name(1)}. The recommended mechanism-independent
   symbolic name for this type is "GSS_C_NT_USER_NAME". (Note: the same
   name form and OID is defined within the Kerberos V5 GSS-API
   mechanism, but the symbolic name recommended there begins with a
   "GSS_KRB5_NT_" prefix.)

   This name type is used to indicate a named user on a local system.
   Its interpretation is OS-specific.  This name form is constructed as:

                                 username

4.3: Machine UID Form

   This name form shall be represented by the Object Identifier {iso(1)
   member-body(2) United States(840) mit(113554) infosys(1) gssapi(2)
   generic(1) machine_uid_name(2)}.  The recommended mechanism-
   independent symbolic name for this type is
   "GSS_C_NT_MACHINE_UID_NAME".  (Note: the same name form and OID is
   defined within the Kerberos V5 GSS-API mechanism, but the symbolic
   name recommended there begins with a "GSS_KRB5_NT_" prefix.)

   This name type is used to indicate a numeric user identifier
   corresponding to a user on a local system.  Its interpretation is
   OS-specific.  The gss_buffer_desc representing a name of this type
   should contain a locally-significant uid_t, represented in host byte



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   order.  The GSS_Import_name() operation resolves this uid into a
   username, which is then treated as the User Name Form.

4.4: String UID Form

   This name form shall be represented by the Object Identifier {iso(1)
   member-body(2) United States(840) mit(113554) infosys(1) gssapi(2)
   generic(1) string_uid_name(3)}.  The recommended symbolic name for
   this type is "GSS_C_NT_STRING_UID_NAME".  (Note: the same name form
   and OID is defined within the Kerberos V5 GSS-API mechanism, but the
   symbolic name recommended there begins with a "GSS_KRB5_NT_" prefix.)

   This name type is used to indicate a string of digits representing
   the numeric user identifier of a user on a local system.  Its
   interpretation is OS-specific. This name type is similar to the
   Machine UID Form, except that the buffer contains a string
   representing the uid_t.

5:  Mechanism-Specific Example Scenarios

   This section provides illustrative overviews of the use of various
   candidate mechanism types to support the GSS-API. These discussions
   are intended primarily for readers familiar with specific security
   technologies, demonstrating how GSS-API functions can be used and
   implemented by candidate underlying mechanisms. They should not be
   regarded as constrictive to implementations or as defining the only
   means through which GSS-API functions can be realized with a
   particular underlying technology, and do not demonstrate all GSS-API
   features with each technology.

5.1: Kerberos V5, single-TGT

   OS-specific login functions yield a TGT to the local realm Kerberos
   server; TGT is placed in a credentials structure for the client.
   Client calls GSS_Acquire_cred()  to acquire a cred_handle in order to
   reference the credentials for use in establishing security contexts.

   Client calls GSS_Init_sec_context().  If the requested service is
   located in a different realm, GSS_Init_sec_context()  gets the
   necessary TGT/key pairs needed to traverse the path from local to
   target realm; these data are placed in the owner's TGT cache. After
   any needed remote realm resolution, GSS_Init_sec_context()  yields a
   service ticket to the requested service with a corresponding session
   key; these data are stored in conjunction with the context. GSS-API
   code sends KRB_TGS_REQ request(s) and receives KRB_TGS_REP
   response(s) (in the successful case) or KRB_ERROR.





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   Assuming success, GSS_Init_sec_context()  builds a Kerberos-formatted
   KRB_AP_REQ message, and returns it in output_token.  The client sends
   the output_token to the service.

   The service passes the received token as the input_token argument to
   GSS_Accept_sec_context(),  which verifies the authenticator, provides
   the service with the client's authenticated name, and returns an
   output_context_handle.

   Both parties now hold the session key associated with the service
   ticket, and can use this key in subsequent GSS_GetMIC(),
   GSS_VerifyMIC(),  GSS_Wrap(), and GSS_Unwrap() operations.

5.2: Kerberos V5, double-TGT

   TGT acquisition as above.

   Note: To avoid unnecessary frequent invocations of error paths when
   implementing the GSS-API atop Kerberos V5, it seems appropriate to
   represent "single-TGT K-V5" and "double-TGT K-V5" with separate
   mech_types, and this discussion makes that assumption.

   Based on the (specified or defaulted) mech_type,
   GSS_Init_sec_context()  determines that the double-TGT protocol
   should be employed for the specified target. GSS_Init_sec_context()
   returns GSS_S_CONTINUE_NEEDED major_status, and its returned
   output_token contains a request to the service for the service's TGT.
   (If a service TGT with suitably long remaining lifetime already
   exists in a cache, it may be usable, obviating the need for this
   step.) The client passes the output_token to the service.  Note: this
   scenario illustrates a different use for the GSS_S_CONTINUE_NEEDED
   status return facility than for support of mutual authentication;
   note that both uses can coexist as successive operations within a
   single context establishment operation.

   The service passes the received token as the input_token argument to
   GSS_Accept_sec_context(),  which recognizes it as a request for TGT.
   (Note that current Kerberos V5 defines no intra-protocol mechanism to
   represent such a request.) GSS_Accept_sec_context()  returns
   GSS_S_CONTINUE_NEEDED major_status and provides the service's TGT in
   its output_token. The service sends the output_token to the client.

   The client passes the received token as the input_token argument to a
   continuation of GSS_Init_sec_context(). GSS_Init_sec_context() caches
   the received service TGT and uses it as part of a service ticket
   request to the Kerberos authentication server, storing the returned
   service ticket and session key in conjunction with the context.
   GSS_Init_sec_context()  builds a Kerberos-formatted authenticator,



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   and returns it in output_token along with GSS_S_COMPLETE return
   major_status. The client sends the output_token to the service.

   Service passes the received token as the input_token argument to a
   continuation call to GSS_Accept_sec_context().
   GSS_Accept_sec_context()  verifies the authenticator, provides the
   service with the client's authenticated name, and returns
   major_status GSS_S_COMPLETE.

   GSS_GetMIC(),  GSS_VerifyMIC(), GSS_Wrap(), and GSS_Unwrap()  as
   above.

5.3:  X.509 Authentication Framework

   This example illustrates use of the GSS-API in conjunction with
   public-key mechanisms, consistent with the X.509 Directory
   Authentication Framework.

   The GSS_Acquire_cred()  call establishes a credentials structure,
   making the client's private key accessible for use on behalf of the
   client.

   The client calls GSS_Init_sec_context(),  which interrogates the
   Directory to acquire (and validate) a chain of public-key
   certificates, thereby collecting the public key of the service.  The
   certificate validation operation determines that suitable integrity
   checks were applied by trusted authorities and that those
   certificates have not expired. GSS_Init_sec_context()  generates a
   secret key for use in per-message protection operations on the
   context, and enciphers that secret key under the service's public
   key.

   The enciphered secret key, along with an authenticator quantity
   signed with the client's private key, is included in the output_token
   from GSS_Init_sec_context().  The output_token also carries a
   certification path, consisting of a certificate chain leading from
   the service to the client; a variant approach would defer this path
   resolution to be performed by the service instead of being asserted
   by the client. The client application sends the output_token to the
   service.

   The service passes the received token as the input_token argument to
   GSS_Accept_sec_context().  GSS_Accept_sec_context() validates the
   certification path, and as a result determines a certified binding
   between the client's distinguished name and the client's public key.
   Given that public key, GSS_Accept_sec_context() can process the
   input_token's authenticator quantity and verify that the client's
   private key was used to sign the input_token. At this point, the



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   client is authenticated to the service. The service uses its private
   key to decipher the enciphered secret key provided to it for per-
   message protection operations on the context.

   The client calls GSS_GetMIC()  or GSS_Wrap() on a data message, which
   causes per-message authentication, integrity, and (optional)
   confidentiality facilities to be applied to that message. The service
   uses the context's shared secret key to perform corresponding
   GSS_VerifyMIC()  and GSS_Unwrap() calls.

6:  Security Considerations

   Security issues are discussed throughout this memo.

7:  Related Activities

   In order to implement the GSS-API atop existing, emerging, and future
   security mechanisms:

      object identifiers must be assigned to candidate GSS-API
      mechanisms and the name types which they support

      concrete data element formats and processing procedures must be
      defined for candidate mechanisms

   Calling applications must implement formatting conventions which will
   enable them to distinguish GSS-API tokens from other data carried in
   their application protocols.

   Concrete language bindings are required for the programming
   environments in which the GSS-API is to be employed, as RFC-1509
   defines for the C programming language and GSS-V1.



















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APPENDIX A

MECHANISM DESIGN CONSTRAINTS

   The following constraints on GSS-API mechanism designs are adopted in
   response to observed caller protocol requirements, and adherence
   thereto is anticipated in subsequent descriptions of GSS-API
   mechanisms to be documented in standards-track Internet
   specifications.

   It is strongly recommended that mechanisms offering per-message
   protection services also offer at least one of the replay detection
   and sequencing services, as mechanisms offering neither of the latter
   will fail to satisfy recognized requirements of certain candidate
   caller protocols.

APPENDIX B

                         COMPATIBILITY WITH GSS-V1

   It is the intent of this document to define an interface and
   procedures which preserve compatibility between GSS-V1 (RFC-1508)
   callers and GSS- V2 providers.  All calls defined in GSS-V1 are
   preserved, and it has been a goal that GSS-V1 callers should be able
   to operate atop GSS-V2 provider implementations.  Certain detailed
   changes, summarized in this section, have been made in order to
   resolve omissions identified in GSS-V1.

   The following GSS-V1 constructs, while supported within GSS-V2, are
   deprecated:

      Names for per-message processing routines: GSS_Seal() deprecated
      in favor of GSS_Wrap(); GSS_Sign() deprecated in favor of
      GSS_GetMIC(); GSS_Unseal() deprecated in favor of GSS_Unwrap();
      GSS_Verify() deprecated in favor of GSS_VerifyMIC().

      GSS_Delete_sec_context() facility for context_token usage,
      allowing mechanisms to signal context deletion, is retained for
      compatibility with GSS-V1.  For current usage, it is recommended
      that both peers to a context invoke GSS_Delete_sec_context()
      independently, passing a null output_context_token buffer to
      indicate that no context_token is required.  Implementations of
      GSS_Delete_sec_context() should delete relevant locally-stored
      context information.







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   This GSS-V2 specification adds the following calls which are not
   present in GSS-V1:

      Credential management calls: GSS_Add_cred(),
      GSS_Inquire_cred_by_mech().

      Context-level calls: GSS_Inquire_context(), GSS_Wrap_size_limit(),
      GSS_Export_sec_context(), GSS_Import_sec_context().

      Per-message calls: No new calls.  Existing calls have been renamed.

      Support calls: GSS_Create_empty_OID_set(),
      GSS_Add_OID_set_member(), GSS_Test_OID_set_member(),
      GSS_Release_OID(), GSS_OID_to_str(), GSS_Str_to_OID(),
      GSS_Inquire_names_for_mech(), GSS_Inquire_mechs_for_name(),
      GSS_Canonicalize_name(), GSS_Export_name(), GSS_Duplicate_name().

   This GSS-V2 specification introduces three new facilities applicable
   to security contexts, indicated using the following context state
   values which are not present in GSS-V1:

      anon_state, set TRUE to indicate that a context's initiator is
      anonymous from the viewpoint of the target; Section 1.2.5 of this
      specification provides a summary description of the GSS-V2
      anonymity support facility, support and use of which is optional.

      prot_ready_state, set TRUE to indicate that a context may be used
      for per-message protection before final completion of context
      establishment; Section 1.2.7 of this specification provides a
      summary description of the GSS-V2 facility enabling mechanisms to
      selectively permit per-message protection during context
      establishment, support and use of which is optional.

      trans_state, set TRUE to indicate that a context is transferable to
      another process using the GSS-V2 GSS_Export_sec_context() facility.

   These state values are represented (at the C bindings level) in
   positions within a bit vector which are unused in GSS-V1, and may be
   safely ignored by GSS-V1 callers.

   Relative to GSS-V1, GSS-V2 provides additional guidance to GSS-API
   implementors in the following areas: implementation robustness,
   credential management, behavior in multi-mechanism configurations,
   naming support, and inclusion of optional sequencing services.  The
   token tagging facility as defined in GSS-V2, Section 3.1, is now
   described directly in terms of octets to facilitate interoperable
   implementation without general ASN.1 processing code; the
   corresponding ASN.1 syntax, included for descriptive purposes, is



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RFC 2078                        GSS-API                     January 1997


   unchanged from that in GSS-V1. For use in conjunction with added
   naming support facilities, a new Exported Name Object construct is
   added.  Additional name types are introduced in Section 4.

   This GSS-V2 specification adds the following major_status values
   which are not defined in GSS-V1:

     GSS_S_BAD_QOP                 unsupported QOP value
     GSS_S_UNAUTHORIZED            operation unauthorized
     GSS_S_UNAVAILABLE             operation unavailable
     GSS_S_DUPLICATE_ELEMENT       duplicate credential element requested
     GSS_S_NAME_NOT_MN             name contains multi-mechanism elements
     GSS_S_GAP_TOKEN               skipped predecessor token(s)
                                    detected

   Of these added status codes, only two values are defined to be
   returnable by calls existing in GSS-V1: GSS_S_BAD_QOP (returnable by
   GSS_GetMIC() and GSS_Wrap()), and GSS_S_GAP_TOKEN (returnable by
   GSS_VerifyMIC() and GSS_Unwrap()).

   Additionally, GSS-V2 descriptions of certain calls present in GSS-V1
   have been updated to allow return of additional major_status values
   from the set as defined in GSS-V1: GSS_Inquire_cred() has
   GSS_S_DEFECTIVE_CREDENTIAL and GSS_S_CREDENTIALS_EXPIRED defined as
   returnable, GSS_Init_sec_context() has GSS_S_OLD_TOKEN,
   GSS_S_DUPLICATE_TOKEN, and GSS_S_BAD_MECH defined as returnable, and
   GSS_Accept_sec_context() has GSS_S_BAD_MECH defined as returnable.

Author's Address

   John Linn
   OpenVision Technologies
   One Main St.
   Cambridge, MA  02142  USA

   Phone: +1 617.374.2245
   EMail: John.Linn@ov.com














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