path: root/doc/rfc/rfc8353.txt

Internet Engineering Task Force (IETF)                       M. Upadhyay
Request for Comments: 8353                                        Google
Obsoletes: 5653                                               S. Malkani
Category: Standards Track                                  ActivIdentity
ISSN: 2070-1721                                                  W. Wang
                                                                  Oracle
                                                                May 2018


      Generic Security Service API Version 2: Java Bindings Update

Abstract

   The Generic Security Services Application Programming Interface
   (GSS-API) offers application programmers uniform access to security
   services atop a variety of underlying cryptographic mechanisms.  This
   document updates the Java bindings for the GSS-API that are specified
   in "Generic Security Service API Version 2: Java Bindings Update"
   (RFC 5653).  This document obsoletes RFC 5653 by adding a new output
   token field to the GSSException class so that when the initSecContext
   or acceptSecContext methods of the GSSContext class fail, it has a
   chance to emit an error token that can be sent to the peer for
   debugging or informational purpose.  The stream-based GSSContext
   methods are also removed in this version.

   The GSS-API is described at a language-independent conceptual level
   in "Generic Security Service Application Program Interface Version 2,
   Update 1" (RFC 2743).  The GSS-API allows a caller application to
   authenticate a principal identity, to delegate rights to a peer, and
   to apply security services such as confidentiality and integrity on a
   per-message basis.  Examples of security mechanisms defined for
   GSS-API are "The Simple Public-Key GSS-API Mechanism (SPKM)"
   (RFC 2025) and "The Kerberos Version 5 Generic Security Service
   Application Program Interface (GSS-API) Mechanism: Version 2"
   (RFC 4121).
















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Status of This Memo

   This is an Internet Standards Track document.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Further information on
   Internet Standards is available in Section 2 of RFC 7841.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   https://www.rfc-editor.org/info/rfc8353.

Copyright Notice

   Copyright (c) 2018 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (https://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document.  Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   described in the Simplified BSD License.

   This document may contain material from IETF Documents or IETF
   Contributions published or made publicly available before November
   10, 2008.  The person(s) controlling the copyright in some of this
   material may not have granted the IETF Trust the right to allow
   modifications of such material outside the IETF Standards Process.
   Without obtaining an adequate license from the person(s) controlling
   the copyright in such materials, this document may not be modified
   outside the IETF Standards Process, and derivative works of it may
   not be created outside the IETF Standards Process, except to format
   it for publication as an RFC or to translate it into languages other
   than English.











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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   6
   2.  Notational Conventions  . . . . . . . . . . . . . . . . . . .   7
   3.  GSS-API Operational Paradigm  . . . . . . . . . . . . . . . .   7
   4.  Additional Controls . . . . . . . . . . . . . . . . . . . . .   9
     4.1.  Delegation  . . . . . . . . . . . . . . . . . . . . . . .  10
     4.2.  Mutual Authentication . . . . . . . . . . . . . . . . . .  11
     4.3.  Replay and Out-of-Sequence Detection  . . . . . . . . . .  11
     4.4.  Anonymous Authentication  . . . . . . . . . . . . . . . .  12
     4.5.  Integrity and Confidentiality . . . . . . . . . . . . . .  13
     4.6.  Inter-process Context Transfer  . . . . . . . . . . . . .  13
     4.7.  The Use of Incomplete Contexts  . . . . . . . . . . . . .  14
   5.  Calling Conventions . . . . . . . . . . . . . . . . . . . . .  15
     5.1.  Package Name  . . . . . . . . . . . . . . . . . . . . . .  15
     5.2.  Provider Framework  . . . . . . . . . . . . . . . . . . .  15
     5.3.  Integer Types . . . . . . . . . . . . . . . . . . . . . .  16
     5.4.  Opaque Data Types . . . . . . . . . . . . . . . . . . . .  16
     5.5.  Strings . . . . . . . . . . . . . . . . . . . . . . . . .  16
     5.6.  Object Identifiers  . . . . . . . . . . . . . . . . . . .  16
     5.7.  Object Identifier Sets  . . . . . . . . . . . . . . . . .  17
     5.8.  Credentials . . . . . . . . . . . . . . . . . . . . . . .  17
     5.9.  Contexts  . . . . . . . . . . . . . . . . . . . . . . . .  19
     5.10. Authentication Tokens . . . . . . . . . . . . . . . . . .  20
     5.11. Inter-process Tokens  . . . . . . . . . . . . . . . . . .  20
     5.12. Error Reporting . . . . . . . . . . . . . . . . . . . . .  20
       5.12.1.  GSS Status Codes . . . . . . . . . . . . . . . . . .  21
       5.12.2.  Mechanism-Specific Status Codes  . . . . . . . . . .  23
       5.12.3.  Supplementary Status Codes . . . . . . . . . . . . .  23
     5.13. Names . . . . . . . . . . . . . . . . . . . . . . . . . .  24
     5.14. Channel Bindings  . . . . . . . . . . . . . . . . . . . .  27
     5.15. Optional Parameters . . . . . . . . . . . . . . . . . . .  28
   6.  Introduction to GSS-API Classes and Interfaces  . . . . . . .  28
     6.1.  GSSManager Class  . . . . . . . . . . . . . . . . . . . .  28
     6.2.  GSSName Interface . . . . . . . . . . . . . . . . . . . .  29
     6.3.  GSSCredential Interface . . . . . . . . . . . . . . . . .  30
     6.4.  GSSContext Interface  . . . . . . . . . . . . . . . . . .  31
     6.5.  MessageProp Class . . . . . . . . . . . . . . . . . . . .  32
     6.6.  GSSException Class  . . . . . . . . . . . . . . . . . . .  32
     6.7.  Oid Class . . . . . . . . . . . . . . . . . . . . . . . .  32
     6.8.  ChannelBinding Class  . . . . . . . . . . . . . . . . . .  33
   7.  Detailed GSS-API Class Description  . . . . . . . . . . . . .  33
     7.1.  public abstract class GSSManager  . . . . . . . . . . . .  33
       7.1.1.  getInstance . . . . . . . . . . . . . . . . . . . . .  34
       7.1.2.  getMechs  . . . . . . . . . . . . . . . . . . . . . .  34
       7.1.3.  getNamesForMech . . . . . . . . . . . . . . . . . . .  35
       7.1.4.  getMechsForName . . . . . . . . . . . . . . . . . . .  35
       7.1.5.  createName  . . . . . . . . . . . . . . . . . . . . .  35



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       7.1.6.  createName  . . . . . . . . . . . . . . . . . . . . .  36
       7.1.7.  createName  . . . . . . . . . . . . . . . . . . . . .  36
       7.1.8.  createName  . . . . . . . . . . . . . . . . . . . . .  37
       7.1.9.  createCredential  . . . . . . . . . . . . . . . . . .  38
       7.1.10. createCredential  . . . . . . . . . . . . . . . . . .  38
       7.1.11. createCredential  . . . . . . . . . . . . . . . . . .  39
       7.1.12. createContext . . . . . . . . . . . . . . . . . . . .  39
       7.1.13. createContext . . . . . . . . . . . . . . . . . . . .  40
       7.1.14. createContext . . . . . . . . . . . . . . . . . . . .  40
       7.1.15. addProviderAtFront  . . . . . . . . . . . . . . . . .  41
         7.1.15.1.  addProviderAtFront Example Code  . . . . . . . .  42
       7.1.16. addProviderAtEnd  . . . . . . . . . . . . . . . . . .  43
         7.1.16.1.  addProviderAtEnd Example Code  . . . . . . . . .  43
       7.1.17. Example Code  . . . . . . . . . . . . . . . . . . . .  44
     7.2.  public interface GSSName  . . . . . . . . . . . . . . . .  45
       7.2.1.  Static Constants  . . . . . . . . . . . . . . . . . .  45
       7.2.2.  equals  . . . . . . . . . . . . . . . . . . . . . . .  46
       7.2.3.  equals  . . . . . . . . . . . . . . . . . . . . . . .  46
       7.2.4.  canonicalize  . . . . . . . . . . . . . . . . . . . .  47
       7.2.5.  export  . . . . . . . . . . . . . . . . . . . . . . .  47
       7.2.6.  toString  . . . . . . . . . . . . . . . . . . . . . .  47
       7.2.7.  getStringNameType . . . . . . . . . . . . . . . . . .  47
       7.2.8.  isAnonymous . . . . . . . . . . . . . . . . . . . . .  47
       7.2.9.  isMN  . . . . . . . . . . . . . . . . . . . . . . . .  48
       7.2.10. Example Code  . . . . . . . . . . . . . . . . . . . .  48
     7.3.  public interface GSSCredential implements Cloneable . . .  49
       7.3.1.  Static Constants  . . . . . . . . . . . . . . . . . .  50
       7.3.2.  dispose . . . . . . . . . . . . . . . . . . . . . . .  50
       7.3.3.  getName . . . . . . . . . . . . . . . . . . . . . . .  50
       7.3.4.  getName . . . . . . . . . . . . . . . . . . . . . . .  51
       7.3.5.  getRemainingLifetime  . . . . . . . . . . . . . . . .  51
       7.3.6.  getRemainingInitLifetime  . . . . . . . . . . . . . .  51
       7.3.7.  getRemainingAcceptLifetime  . . . . . . . . . . . . .  51
       7.3.8.  getUsage  . . . . . . . . . . . . . . . . . . . . . .  52
       7.3.9.  getUsage  . . . . . . . . . . . . . . . . . . . . . .  52
       7.3.10. getMechs  . . . . . . . . . . . . . . . . . . . . . .  52
       7.3.11. add . . . . . . . . . . . . . . . . . . . . . . . . .  52
       7.3.12. equals  . . . . . . . . . . . . . . . . . . . . . . .  53
       7.3.13. Example Code  . . . . . . . . . . . . . . . . . . . .  54
     7.4.  public interface GSSContext . . . . . . . . . . . . . . .  54
       7.4.1.  Static Constants  . . . . . . . . . . . . . . . . . .  55
       7.4.2.  initSecContext  . . . . . . . . . . . . . . . . . . .  56
       7.4.3.  acceptSecContext  . . . . . . . . . . . . . . . . . .  56
       7.4.4.  isEstablished . . . . . . . . . . . . . . . . . . . .  57
       7.4.5.  dispose . . . . . . . . . . . . . . . . . . . . . . .  57
       7.4.6.  getWrapSizeLimit  . . . . . . . . . . . . . . . . . .  58
       7.4.7.  wrap  . . . . . . . . . . . . . . . . . . . . . . . .  58
       7.4.8.  unwrap  . . . . . . . . . . . . . . . . . . . . . . .  59



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       7.4.9.  getMIC  . . . . . . . . . . . . . . . . . . . . . . .  60
       7.4.10. verifyMIC . . . . . . . . . . . . . . . . . . . . . .  61
       7.4.11. export  . . . . . . . . . . . . . . . . . . . . . . .  62
       7.4.12. requestMutualAuth . . . . . . . . . . . . . . . . . .  62
       7.4.13. requestReplayDet  . . . . . . . . . . . . . . . . . .  63
       7.4.14. requestSequenceDet  . . . . . . . . . . . . . . . . .  63
       7.4.15. requestCredDeleg  . . . . . . . . . . . . . . . . . .  63
       7.4.16. requestAnonymity  . . . . . . . . . . . . . . . . . .  64
       7.4.17. requestConf . . . . . . . . . . . . . . . . . . . . .  64
       7.4.18. requestInteg  . . . . . . . . . . . . . . . . . . . .  64
       7.4.19. requestLifetime . . . . . . . . . . . . . . . . . . .  64
       7.4.20. setChannelBinding . . . . . . . . . . . . . . . . . .  65
       7.4.21. getCredDelegState . . . . . . . . . . . . . . . . . .  65
       7.4.22. getMutualAuthState  . . . . . . . . . . . . . . . . .  65
       7.4.23. getReplayDetState . . . . . . . . . . . . . . . . . .  65
       7.4.24. getSequenceDetState . . . . . . . . . . . . . . . . .  66
       7.4.25. getAnonymityState . . . . . . . . . . . . . . . . . .  66
       7.4.26. isTransferable  . . . . . . . . . . . . . . . . . . .  66
       7.4.27. isProtReady . . . . . . . . . . . . . . . . . . . . .  66
       7.4.28. getConfState  . . . . . . . . . . . . . . . . . . . .  66
       7.4.29. getIntegState . . . . . . . . . . . . . . . . . . . .  67
       7.4.30. getLifetime . . . . . . . . . . . . . . . . . . . . .  67
       7.4.31. getSrcName  . . . . . . . . . . . . . . . . . . . . .  67
       7.4.32. getTargName . . . . . . . . . . . . . . . . . . . . .  67
       7.4.33. getMech . . . . . . . . . . . . . . . . . . . . . . .  67
       7.4.34. getDelegCred  . . . . . . . . . . . . . . . . . . . .  68
       7.4.35. isInitiator . . . . . . . . . . . . . . . . . . . . .  68
       7.4.36. Example Code  . . . . . . . . . . . . . . . . . . . .  68
     7.5.  public class MessageProp  . . . . . . . . . . . . . . . .  70
       7.5.1.  Constructors  . . . . . . . . . . . . . . . . . . . .  70
       7.5.2.  getQOP  . . . . . . . . . . . . . . . . . . . . . . .  71
       7.5.3.  getPrivacy  . . . . . . . . . . . . . . . . . . . . .  71
       7.5.4.  getMinorStatus  . . . . . . . . . . . . . . . . . . .  71
       7.5.5.  getMinorString  . . . . . . . . . . . . . . . . . . .  71
       7.5.6.  setQOP  . . . . . . . . . . . . . . . . . . . . . . .  71
       7.5.7.  setPrivacy  . . . . . . . . . . . . . . . . . . . . .  72
       7.5.8.  isDuplicateToken  . . . . . . . . . . . . . . . . . .  72
       7.5.9.  isOldToken  . . . . . . . . . . . . . . . . . . . . .  72
       7.5.10. isUnseqToken  . . . . . . . . . . . . . . . . . . . .  72
       7.5.11. isGapToken  . . . . . . . . . . . . . . . . . . . . .  72
       7.5.12. setSupplementaryStates  . . . . . . . . . . . . . . .  72
     7.6.  public class ChannelBinding . . . . . . . . . . . . . . .  73
       7.6.1.  Constructors  . . . . . . . . . . . . . . . . . . . .  73
       7.6.2.  getInitiatorAddress . . . . . . . . . . . . . . . . .  74
       7.6.3.  getAcceptorAddress  . . . . . . . . . . . . . . . . .  74
       7.6.4.  getApplicationData  . . . . . . . . . . . . . . . . .  74
       7.6.5.  equals  . . . . . . . . . . . . . . . . . . . . . . .  75




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     7.7.  public class Oid  . . . . . . . . . . . . . . . . . . . .  75
       7.7.1.  Constructors  . . . . . . . . . . . . . . . . . . . .  75
       7.7.2.  toString  . . . . . . . . . . . . . . . . . . . . . .  76
       7.7.3.  equals  . . . . . . . . . . . . . . . . . . . . . . .  76
       7.7.4.  getDER  . . . . . . . . . . . . . . . . . . . . . . .  76
       7.7.5.  containedIn . . . . . . . . . . . . . . . . . . . . .  77
     7.8.  public class GSSException extends Exception . . . . . . .  77
       7.8.1.  Static Constants  . . . . . . . . . . . . . . . . . .  77
       7.8.2.  Constructors  . . . . . . . . . . . . . . . . . . . .  80
       7.8.3.  getMajor  . . . . . . . . . . . . . . . . . . . . . .  81
       7.8.4.  getMinor  . . . . . . . . . . . . . . . . . . . . . .  81
       7.8.5.  getMajorString  . . . . . . . . . . . . . . . . . . .  81
       7.8.6.  getMinorString  . . . . . . . . . . . . . . . . . . .  81
       7.8.7.  getOutputToken  . . . . . . . . . . . . . . . . . . .  82
       7.8.8.  setMinor  . . . . . . . . . . . . . . . . . . . . . .  82
       7.8.9.  toString  . . . . . . . . . . . . . . . . . . . . . .  82
       7.8.10. getMessage  . . . . . . . . . . . . . . . . . . . . .  82
   8.  Sample Applications . . . . . . . . . . . . . . . . . . . . .  83
     8.1.  Simple GSS Context Initiator  . . . . . . . . . . . . . .  83
     8.2.  Simple GSS Context Acceptor . . . . . . . . . . . . . . .  87
   9.  Security Considerations . . . . . . . . . . . . . . . . . . .  90
   10. IANA Considerations . . . . . . . . . . . . . . . . . . . . .  91
   11. Changes since RFC 5653  . . . . . . . . . . . . . . . . . . .  91
   12. Changes since RFC 2853  . . . . . . . . . . . . . . . . . . .  93
   13. References  . . . . . . . . . . . . . . . . . . . . . . . . .  94
     13.1.  Normative References . . . . . . . . . . . . . . . . . .  94
     13.2.  Informative References . . . . . . . . . . . . . . . . .  95
   Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . .  96
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  96

1.  Introduction

   This document specifies Java language bindings for the Generic
   Security Services Application Programming Interface (GSS-API) version
   2.  GSS-API version 2 is described in a language-independent format
   in RFC 2743 [RFC2743].  The GSS-API allows a caller application to
   authenticate a principal identity, delegate rights to a peer, and
   apply security services such as confidentiality and integrity on a
   per-message basis.

   This document and its predecessors, RFC 2853 [RFC2853] and RFC 5653
   [RFC5653], leverage the work done by the working group (WG) in the
   area of RFC 2743 [RFC2743] and the C-bindings of RFC 2744 [RFC2744].
   Whenever appropriate, text has been used from the C-bindings document
   (RFC 2744) to explain generic concepts and provide direction to the
   implementors.





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   The design goals of this API have been to satisfy all the
   functionality defined in RFC 2743 [RFC2743] and to provide these
   services in an object-oriented method.  The specification also aims
   to satisfy the needs of both types of Java application developers,
   those who would like access to a "system-wide" GSS-API
   implementation, as well as those who would want to provide their own
   "custom" implementation.

   A system-wide implementation is one that is available to all
   applications in the form of a library package.  It may be the
   standard package in the Java runtime environment (JRE) being used, or
   it may be additionally installed and accessible to any application
   via the CLASSPATH.

   A custom implementation of the GSS-API, on the other hand, is one
   that would, in most cases, be bundled with the application during
   distribution.  It is expected that such an implementation would be
   meant to provide for some particular need of the application, such as
   support for some specific mechanism.

   The design of this API also aims to provide a flexible framework to
   add and manage GSS-API mechanisms.  GSS-API leverages the Java
   Cryptography Architecture (JCA) provider model to support the
   plugability of mechanisms.  Mechanisms can be added on a system-wide
   basis, where all users of the framework will have them available.
   The specification also allows for the addition of mechanisms per
   instance of the GSS-API.

   Lastly, this specification presents an API that will naturally fit
   within the operation environment of the Java platform.  Readers are
   assumed to be familiar with both the GSS-API and the Java platform.

2.  Notational Conventions

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
   "OPTIONAL" in this document are to be interpreted as described in
   BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
   capitals, as shown here.

3.  GSS-API Operational Paradigm

   "Generic Security Service Application Programming Interface, Version
   2" [RFC2743] defines a generic security API to calling applications.
   It allows a communicating application to authenticate the user
   associated with another application, to delegate rights to another
   application, and to apply security services such as confidentiality
   and integrity on a per-message basis.



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   There are four stages to using GSS-API:

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

   2) A pair of communicating applications establish a joint security
      context using their credentials.  The security context
      encapsulates shared state information, which is required in order
      that per-message security services may be provided.  Examples of
      state information that might be shared between applications as
      part of a security context are cryptographic keys and message
      sequence numbers.  As part of the establishment of a security
      context, the context initiator is authenticated to the responder
      and may require that the responder is authenticated back to the
      initiator.  The initiator may optionally give the responder the
      right to initiate further security contexts, acting as an agent or
      delegate of the initiator.  This transfer of rights is termed
      "delegation" and is achieved by creating a set of credentials,
      similar to those used by the initiating application, but which may
      be used by the responder.

      A GSSContext object is used to establish and maintain the shared
      information that makes up the security context.  Certain
      GSSContext methods will generate a token, which applications treat
      as cryptographically protected, opaque data.  The caller of such a
      GSSContext method is responsible for transferring the token to the
      peer application, encapsulated if necessary in an application-to-
      application protocol.  On receipt of such a token, the peer
      application should pass it to a corresponding GSSContext method,
      which will decode the token and extract the information, updating
      the security context state information accordingly.

   3) Per-message services are invoked on a GSSContext object to apply
      either:

      integrity and data origin authentication, or

      confidentiality, integrity, and data origin authentication

      to application data, which are treated by GSS-API as arbitrary
      octet strings.  An application transmitting a message that it
      wishes to protect will call the appropriate GSSContext method
      (getMIC or wrap) to apply protection before sending the resulting
      token to the receiving application.  The receiver will pass the
      received token (and, in the case of data protected by getMIC, the




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      accompanying message data) to the corresponding decoding method of
      the GSSContext interface (verifyMIC or unwrap) to remove the
      protection and validate the data.

   4) At the completion of a communications session (which may extend
      across several transport connections), each application uses a
      GSSContext method to invalidate the security context and release
      any system or cryptographic resources held.  Multiple contexts may
      also be used (either successively or simultaneously) within a
      single communications association, at the discretion of the
      applications.

4.  Additional Controls

   This section discusses the OPTIONAL services that a context initiator
   may request of the GSS-API before the context establishment.  Each of
   these services is requested by calling the appropriate mutator method
   in the GSSContext object before the first call to init is performed.
   Only the context initiator can request context flags.

   The OPTIONAL services defined are:

      Delegation: The (usually temporary) transfer of rights from
      initiator to acceptor, enabling the acceptor to authenticate
      itself as an agent of the initiator.

      Mutual Authentication: In addition to the initiator authenticating
      its identity to the context acceptor, the context acceptor SHOULD
      also authenticate itself to the initiator.

      Replay Detection: In addition to providing message integrity
      services, GSSContext per-message operations of getMIC and wrap
      SHOULD include message numbering information to enable verifyMIC
      and unwrap to detect if a message has been duplicated.

      Out-of-Sequence Detection: In addition to providing message
      integrity services, GSSContext per-message operations (getMIC and
      wrap) SHOULD include message sequencing information to enable
      verifyMIC and unwrap to detect if a message has been received out
      of sequence.

      Anonymous Authentication: The establishment of the security
      context SHOULD NOT reveal the initiator's identity to the context
      acceptor.

   Some mechanisms may not support all OPTIONAL services, and some
   mechanisms may only support some services in conjunction with others.
   The GSSContext interface offers query methods to allow the



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   verification by the calling application of which services will be
   available from the context when the establishment phase is complete.
   In general, if the security mechanism is capable of providing a
   requested service, it SHOULD do so even if additional services must
   be enabled in order to provide the requested service.  If the
   mechanism is incapable of providing a requested service, it SHOULD
   proceed without the service leaving the application to abort the
   context establishment process if it considers the requested service
   to be mandatory.

   Some mechanisms MAY specify that support for some services is
   optional and that implementors of the mechanism need not provide it.
   This is most commonly true of the confidentiality service, often
   because of legal restrictions on the use of data encryption, but it
   may apply to any of the services.  Such mechanisms are required to
   send at least one token from acceptor to initiator during context
   establishment when the initiator indicates a desire to use such a
   service, so that the initiating GSS-API can correctly indicate
   whether the service is supported by the acceptor's GSS-API.

4.1.  Delegation

   The GSS-API allows delegation to be controlled by the initiating
   application via the requestCredDeleg method before the first call to
   init has been issued.  Some mechanisms do not support delegation, and
   for such mechanisms, attempts by an application to enable delegation
   are ignored.

   The acceptor of a security context, for which the initiator enabled
   delegation, can check if delegation was enabled by using the
   getCredDelegState method of the GSSContext interface.  In cases when
   it is enabled, the delegated credential object can be obtained by
   calling the getDelegCred method.  The obtained GSSCredential object
   may then be used to initiate subsequent GSS-API security contexts as
   an agent or delegate of the initiator.  If the original initiator's
   identity is "A" and the delegate's identity is "B", then, depending
   on the underlying mechanism, the identity embodied by the delegated
   credential may be either "A" or "B acting for A".

   For many mechanisms that support delegation, a simple boolean does
   not provide enough control.  Examples of additional aspects of
   delegation control that a mechanism might provide to an application
   are duration of delegation, network addresses from which delegation
   is valid, and constraints on the tasks that may be performed by a
   delegate.  Such controls are presently outside the scope of the
   GSS-API.  GSS-API implementations supporting mechanisms offering
   additional controls SHOULD provide extension routines that allow
   these controls to be exercised (perhaps by modifying the initiator's



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   GSS-API credential object prior to its use in establishing a
   context).  However, the simple delegation control provided by GSS-API
   SHOULD always be able to override other mechanism-specific delegation
   controls.  If the application instructs the GSSContext object that
   delegation is not desired, then the implementation MUST NOT permit
   delegation to occur.  This is an exception to the general rule that a
   mechanism may enable services even if they are not requested --
   delegation may only be provided at the explicit request of the
   application.

4.2.  Mutual Authentication

   Usually, a context acceptor will require that a context initiator
   authenticate itself so that the acceptor may make an access-control
   decision prior to performing a service for the initiator.  In some
   cases, the initiator may also request that the acceptor authenticate
   itself.  GSS-API allows the initiating application to request this
   mutual authentication service by calling the requestMutualAuth method
   of the GSSContext interface with a "true" parameter before making the
   first call to init.  The initiating application is informed as to
   whether or not the context acceptor has authenticated itself.  Note
   that some mechanisms may not support mutual authentication, and other
   mechanisms may always perform mutual authentication, whether or not
   the initiating application requests it.  In particular, mutual
   authentication may be required by some mechanisms in order to support
   replay or out-of-sequence message detection, and for such mechanisms,
   a request for either of these services will automatically enable
   mutual authentication.

4.3.  Replay and Out-of-Sequence Detection

   The GSS-API MAY provide detection of mis-ordered messages once a
   security context has been established.  Protection MAY be applied to
   messages by either application, by calling either getMIC or wrap
   methods of the GSSContext interface, and verified by the peer
   application by calling verifyMIC or unwrap for the peer's GSSContext
   object.

   The getMIC method calculates a cryptographic checksum (authentication
   tag) of an application message, and returns that checksum in a token.
   The application SHOULD pass both the token and the message to the
   peer application, which presents them to the verifyMIC method of the
   peer's GSSContext object.








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   The wrap method calculates a cryptographic checksum of an application
   message, and places both the checksum and the message inside a single
   token.  The application SHOULD pass the token to the peer
   application, which presents it to the unwrap method of the peer's
   GSSContext object to extract the message and verify the checksum.

   Either pair of routines may be capable of detecting out-of-sequence
   message delivery or the duplication of messages.  Details of such
   mis-ordered messages are indicated through supplementary query
   methods of the MessageProp object that is filled in by each of these
   routines.

   A mechanism need not maintain a list of all tokens that have been
   processed in order to support these status codes.  A typical
   mechanism might retain information about only the most recent "N"
   tokens processed, allowing it to distinguish duplicates and missing
   tokens within the most recent "N" messages; the receipt of a token
   older than the most recent "N" would result in the isOldToken method
   of the instance of MessageProp to return "true".

4.4.  Anonymous Authentication

   In certain situations, an application may wish to initiate the
   authentication process to authenticate a peer, without revealing its
   own identity.  As an example, consider an application providing
   access to a database containing medical information and offering
   unrestricted access to the service.  A client of such a service might
   wish to authenticate the service (in order to establish trust in any
   information retrieved from it), but might not wish the service to be
   able to obtain the client's identity (perhaps due to privacy concerns
   about the specific inquiries, or perhaps simply to avoid being placed
   on mailing-lists).

   In normal use of the GSS-API, the initiator's identity is made
   available to the acceptor as a result of the context establishment
   process.  However, context initiators may request that their identity
   not be revealed to the context acceptor.  Many mechanisms do not
   support anonymous authentication, and for such mechanisms, the
   request will not be honored.  An authentication token will still be
   generated, but the application is always informed if a requested
   service is unavailable, and has the option to abort context
   establishment if anonymity is valued above the other security
   services that would require a context to be established.

   In addition to informing the application that a context is
   established anonymously (via the isAnonymous method of the GSSContext
   class), the getSrcName method of the acceptor's GSSContext object




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   will, for such contexts, return a reserved internal-form name,
   defined by the implementation.

   The toString method for a GSSName object representing an anonymous
   entity will return a printable name.  The returned value will be
   syntactically distinguishable from any valid principal name supported
   by the implementation.  The associated name-type Object Identifier
   (OID) will be an OID representing the value of NT_ANONYMOUS.  This
   name-type OID will be defined as a public, static Oid object of the
   GSSName class.  The printable form of an anonymous name SHOULD be
   chosen such that it implies anonymity, since this name may appear in,
   for example, audit logs.  For example, the string "<anonymous>" might
   be a good choice, if no valid printable names supported by the
   implementation can begin with "<" and end with ">".

   When using the equal method of the GSSName interface, and one of the
   operands is a GSSName instance representing an anonymous entity, the
   method MUST return "false".

4.5.  Integrity and Confidentiality

   If a GSSContext supports the integrity service, the getMic method may
   be used to create message integrity check tokens on application
   messages.

   If a GSSContext supports the confidentiality service, the wrap method
   may be used to encrypt application messages.  Messages are
   selectively encrypted, under the control of the setPrivacy method of
   the MessageProp object used in the wrap method.  Confidentiality will
   be applied if the privacy state is set to true.

4.6.  Inter-process Context Transfer

   GSS-APIv2 provides functionality that allows a security context to be
   transferred between processes on a single machine.  These are
   implemented using the export method of GSSContext and a byte array
   constructor of the same class.  The most common use for such a
   feature is a client-server design where the server is implemented as
   a single process that accepts incoming security contexts, which then
   launches child processes to deal with the data on these contexts.  In
   such a design, the child processes must have access to the security
   context object created within the parent so that they can use per-
   message protection services and delete the security context when the
   communication session ends.

   Since the security context data structure is expected to contain
   sequencing information, it is impractical in general to share a
   context between processes.  Thus, the GSSContext interface provides



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   an export method that the process, which currently owns the context,
   can call to declare that it has no intention to use the context
   subsequently and to create an inter-process token containing
   information needed by the adopting process to successfully recreate
   the context.  After successful completion of export, the original
   security context is made inaccessible to the calling process by
   GSS-API, and any further usage of this object will result in
   failures.  The originating process transfers the inter-process token
   to the adopting process, which creates a new GSSContext object using
   the byte array constructor.  The properties of the context are
   equivalent to that of the original context.

   The inter-process token MAY contain sensitive data from the original
   security context (including cryptographic keys).  Applications using
   inter-process tokens to transfer security contexts MUST take
   appropriate steps to protect these tokens in transit.

   Implementations are not required to support the inter-process
   transfer of security contexts.  Calling the isTransferable method of
   the GSSContext interface will indicate if the context object is
   transferable.

4.7.  The Use of Incomplete Contexts

   Some mechanisms may allow the per-message services to be used before
   the context establishment process is complete.  For example, a
   mechanism may include sufficient information in its initial context-
   level tokens for the context acceptor to immediately decode messages
   protected with wrap or getMIC.  For such a mechanism, the initiating
   application need not wait until subsequent context-level tokens have
   been sent and received before invoking the per-message protection
   services.

   An application can invoke the isProtReady method of the GSSContext
   class to determine if the per-message services are available in
   advance of complete context establishment.  Applications wishing to
   use per-message protection services on partially established contexts
   SHOULD query this method before attempting to invoke wrap or getMIC.













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5.  Calling Conventions

   Java provides the implementors with not just a syntax for the
   language but also an operational environment.  For example, memory is
   automatically managed and does not require application intervention.
   These language features have allowed for a simpler API and have led
   to the elimination of certain GSS-API functions.

   Moreover, the JCA defines a provider model that allows for
   implementation-independent access to security services.  Using this
   model, applications can seamlessly switch between different
   implementations and dynamically add new services.  The GSS-API
   specification leverages these concepts by the usage of providers for
   the mechanism implementations.

5.1.  Package Name

   The classes and interfaces defined in this document reside in the
   package called "org.ietf.jgss".  Applications that wish to make use
   of this API should import this package name as shown in Section 8.

5.2.  Provider Framework

   Java security APIs use a provider architecture that allows
   applications to be implementation independent and security API
   implementations to be modular and extensible.  The
   java.security.Provider class is an abstract class that a vendor
   extends.  This class maps various properties that represent different
   security services that are available to the names of the actual
   vendor classes that implement those services.  When requesting a
   service, an application simply specifies the desired provider, and
   the API delegates the request to service classes available from that
   provider.

   Using the Java security provider model insulates applications from
   implementation details of the services they wish to use.
   Applications can switch between providers easily, and new providers
   can be added as needed, even at runtime.

   The GSS-API may use providers to find components for specific
   underlying security mechanisms.  For instance, a particular provider
   might contain components that will allow the GSS-API to support the
   Kerberos v5 mechanism [RFC4121], and another might contain components
   to support the Simple Public-Key GSS-API Mechanism (SPKM) [RFC2025].
   By delegating mechanism-specific functionality to the components
   obtained from providers, the GSS-API can be extended to support an
   arbitrary list of mechanisms.




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   How the GSS-API locates and queries these providers is beyond the
   scope of this document and is being deferred to a Service Provider
   Interface (SPI) specification.  The availability of such an SPI
   specification is not mandatory for the adoption of this API
   specification nor is it mandatory to use providers in the
   implementation of a GSS-API framework.  However, by using the
   provider framework together with an SPI specification, one can create
   an extensible and implementation-independent GSS-API framework.

5.3.  Integer Types

   All numeric values are declared as the "int" primitive Java type.
   The Java specification guarantees that this will be a 32-bit two's
   complement signed number.

   Throughout this API, the "boolean" primitive Java type is used
   wherever a boolean value is required or returned.

5.4.  Opaque Data Types

   Java byte arrays are used to represent opaque data types that are
   consumed and produced by the GSS-API in the form of tokens.  Java
   arrays contain a length field that enables the users to easily
   determine their size.  The language has automatic garbage collection
   that alleviates the need by developers to release memory and
   simplifies buffer ownership issues.

5.5.  Strings

   The String object will be used to represent all textual data.  The
   Java String object transparently treats all characters as two-byte
   Unicode characters, which allows support for many locals.  All
   routines returning or accepting textual data will use the String
   object.

5.6.  Object Identifiers

   An Oid object will be used to represent Universal Object Identifiers
   (OIDs).  OIDs are ISO-defined, hierarchically globally interpretable
   identifiers used within the GSS-API framework to identify security
   mechanisms and name formats.  The Oid object can be created from a
   string representation of its dot notation (e.g., "1.3.6.1.5.6.2") as
   well as from its ASN.1 DER encoding.  Methods are also provided to
   test equality and provide the DER representation for the object.







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   An important feature of the Oid class is that its instances are
   immutable -- i.e., there are no methods defined that allow one to
   change the contents of an Oid object.  This property allows one to
   treat these objects as "statics" without the need to perform copies.

   Certain routines allow the usage of a default OID.  A "null" value
   can be used in those cases.

5.7.  Object Identifier Sets

   The Java bindings represent Object Identifier sets as arrays of Oid
   objects.  All Java arrays contain a length field, which allows for
   easy manipulation and reference.

   In order to support the full functionality of RFC 2743 [RFC2743], the
   Oid class includes a method that checks for existence of an Oid
   object within a specified array.  This is equivalent in functionality
   to gss_test_oid_set_member.  The use of Java arrays and Java's
   automatic garbage collection has eliminated the need for the
   following routines: gss_create_empty_oid_set, gss_release_oid_set,
   and gss_add_oid_set_member.  Java GSS-API implementations will not
   contain them.  Java's automatic garbage collection and the immutable
   property of the Oid object eliminates the memory management issues of
   the C counterpart.

   Whenever a default value for an Object Identifier set is required, a
   "null" value can be used.  Please consult the detailed method
   description for details.

5.8.  Credentials

   GSS-API credentials are represented by the GSSCredential interface.
   The interface contains several constructs to allow for the creation
   of most common credential objects for the initiator and the acceptor.
   Comparisons are performed using the interface's "equals" method.  The
   following general description of GSS-API credentials is included from
   the C-bindings specification [RFC2744]:

      GSS-API credentials can contain mechanism-specific principal
      authentication data for multiple mechanisms.  A GSS-API credential
      is composed of a set of credential-elements, each of which is
      applicable to a single mechanism.  A credential may contain at
      most one credential-element for each supported mechanism.  A
      credential-element identifies the data needed by a single
      mechanism to authenticate a single principal, and conceptually
      contains two credential-references that describe the actual
      mechanism-specific authentication data, one to be used by GSS-API
      for initiating contexts, and one to be used for accepting



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      contexts.  For mechanisms that do not distinguish between acceptor
      and initiator credentials, both references would point to the same
      underlying mechanism-specific authentication data.

   Credentials describe a set of mechanism-specific principals and give
   their holder the ability to act as any of those principals.  All
   principal identities asserted by a single GSS-API credential SHOULD
   belong to the same entity, although enforcement of this property is
   an implementation-specific matter.  A single GSSCredential object
   represents all the credential elements that have been acquired.

   The creation of a GSSContext object allows the value of "null" to be
   specified as the GSSCredential input parameter.  This will indicate 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:

   For the initiator side of the context:

   1) If there is only a single principal capable of initiating security
      contexts for the chosen mechanism that the application is
      authorized to act on behalf of, then that principal shall be used;
      otherwise,

   2) If the platform maintains a concept of a default network identity
      for the chosen mechanism, 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,

   3) If the platform maintains a concept of a default local identity,
      and provides a means to map local identities into network
      identities for the chosen mechanism, 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 using the chosen mechanism, then the principal
      corresponding to that identity shall be used; otherwise,

   4) A user-configurable default identity should be used.

   For the acceptor side of the context:

   1) If there is only a single authorized principal identity capable of
      accepting security contexts for the chosen mechanism, then that
      principal shall be used; otherwise,





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   2) If the mechanism can determine the identity of the target
      principal by examining the context-establishment token processed
      during the accept method, and if the accepting application is
      authorized to act as that principal for the purpose of accepting
      security contexts using the chosen mechanism, then that principal
      identity shall be used; otherwise,

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

   4) 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
   whenever possible.  Applications requesting default behavior are
   likely to be more portable across mechanisms and implementations than
   ones that instantiate a GSSCredential object representing a specific
   identity.

5.9.  Contexts

   The GSSContext interface is used to represent one end of a GSS-API
   security context, storing state information appropriate to that end
   of the peer communication, including cryptographic state information.
   The instantiation of the context object is done differently by the
   initiator and the acceptor.  After the context has been instantiated,
   the initiator MAY choose to set various context options that will
   determine the characteristics of the desired security context.  When
   all the application-desired characteristics have been set, the
   initiator will call the initSecContext method, which will produce a
   token for consumption by the peer's acceptSecContext method.  It is
   the responsibility of the application to deliver the authentication
   token(s) between the peer applications for processing.  Upon
   completion of the context-establishment phase, context attributes can
   be retrieved, by both the initiator and acceptor, using the accessor
   methods.  These will reflect the actual attributes of the established
   context and might not match the initiator-requested values.  If any
   retrieved attribute does not match the desired value but it is
   necessary for the application protocol, the application SHOULD
   destroy the security context and not use it for application traffic.
   Otherwise, at this point, the context can be used by the application
   to apply cryptographic services to its data.







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5.10.  Authentication Tokens

   A token is a caller-opaque type that GSS-API uses to maintain
   synchronization between each end of the GSS-API security context.
   The token is a cryptographically protected octet string, generated by
   the underlying mechanism at one end of a GSS-API security context for
   use by the peer mechanism at the other end.  Encapsulation (if
   required) within the application protocol and transfer of the token
   are the responsibility of the peer applications.

   Java GSS-API uses byte arrays to represent authentication tokens.

5.11.  Inter-process Tokens

   Certain GSS-API routines are intended to transfer data between
   processes in multi-process programs.  These routines use a caller-
   opaque octet string, generated by the GSS-API in one process for use
   by the GSS-API in another process.  The calling application is
   responsible for transferring such tokens between processes.  Note
   that, while GSS-API implementors are encouraged to avoid placing
   sensitive information within inter-process tokens, or to
   cryptographically protect them, many implementations will be unable
   to avoid placing key material or other sensitive data within them.
   It is the application's responsibility to ensure that inter-process
   tokens are protected in transit and transferred only to processes
   that are trustworthy.  An inter-process token is represented using a
   byte array emitted from the export method of the GSSContext
   interface.  The receiver of the inter-process token would initialize
   a GSSContext object with this token to create a new context.  Once a
   context has been exported, the GSSContext object is invalidated and
   is no longer available.

5.12.  Error Reporting

   RFC 2743 [RFC2743] defined the usage of major and minor status values
   for the signaling of GSS-API errors.  The major code, also called the
   GSS status code, is used to signal errors at the GSS-API level,
   independent of the underlying mechanism(s).  The minor status value
   or Mechanism status code, is a mechanism-defined error value
   indicating a mechanism-specific error code.

   Java GSS-API uses exceptions implemented by the GSSException class to
   signal both minor and major error values.  Both mechanism-specific
   errors and GSS-API level errors are signaled through instances of
   this class.  The usage of exceptions replaces the need for major and
   minor codes to be used within the API calls.  The GSSException class
   also contains methods to obtain textual representations for both the




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   major and minor values, which is equivalent to the functionality of
   gss_display_status.  A GSSException object MAY also include an output
   token that SHOULD be sent to the peer.

   If an exception is thrown during context establishment, the context
   negotiation has failed and the GSSContext object MUST be abandoned.
   If it is thrown in a per-message call, the context MAY remain useful.

5.12.1.  GSS Status Codes

   GSS status codes indicate errors that are independent of the
   underlying mechanism(s) used to provide the security service.  The
   errors that can be indicated via a GSS status code are generic API
   routine errors (errors that are defined in the GSS-API
   specification).  These bindings take advantage of the Java exceptions
   mechanism, thus eliminating the need for calling errors.

   A GSS status code indicates a single fatal generic API error from the
   routine that has thrown the GSSException.  Using exceptions announces
   that a fatal error has occurred during the execution of the method.
   The GSS-API operational model also allows for the signaling of
   supplementary status information from the per-message calls.  These
   need to be handled as return values since using exceptions is not
   appropriate for informatory or warning-like information.  The methods
   that are capable of producing supplementary information are the two
   per-message methods GSSContext.verifyMIC() and GSSContext.unwrap().
   These methods fill the supplementary status codes in the MessageProp
   object that was passed in.

   A GSSException object, along with providing the functionality for
   setting the various error codes and translating them into textual
   representation, also contains the definitions of all the numeric
   error values.  The following table lists the definitions of error
   codes:

















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   Table: GSS Status Codes

   +----------------------+-------+------------------------------------+
   | Name                 | Value | Meaning                            |
   +----------------------+-------+------------------------------------+
   | BAD_BINDINGS         | 1     | Incorrect channel bindings were    |
   |                      |       | supplied.                          |
   | BAD_MECH             | 2     | An unsupported mechanism was       |
   |                      |       | requested.                         |
   | BAD_NAME             | 3     | An invalid name was supplied.      |
   | BAD_NAMETYPE         | 4     | A supplied name was of an          |
   |                      |       | unsupported type.                  |
   | BAD_STATUS           | 5     | An invalid status code was         |
   |                      |       | supplied.                          |
   | BAD_MIC              | 6     | A token had an invalid MIC.        |
   | CONTEXT_EXPIRED      | 7     | The context has expired.           |
   | CREDENTIALS_EXPIRED  | 8     | The referenced credentials have    |
   |                      |       | expired.                           |
   | DEFECTIVE_CREDENTIAL | 9     | A supplied credential was invalid. |
   | DEFECTIVE_TOKEN      | 10    | A supplied token was invalid.      |
   | FAILURE              | 11    | Miscellaneous failure, unspecified |
   |                      |       | at the GSS-API level.              |
   | NO_CONTEXT           | 12    | Invalid context has been supplied. |
   | NO_CRED              | 13    | No credentials were supplied, or   |
   |                      |       | the credentials were unavailable   |
   |                      |       | or inaccessible.                   |
   | BAD_QOP              | 14    | The quality of protection (QOP)    |
   |                      |       | requested could not be provided.   |
   | UNAUTHORIZED         | 15    | The operation is forbidden by the  |
   |                      |       | local security policy.             |
   | UNAVAILABLE          | 16    | The operation or option is         |
   |                      |       | unavailable.                       |
   | DUPLICATE_ELEMENT    | 17    | The requested credential element   |
   |                      |       | already exists.                    |
   | NAME_NOT_MN          | 18    | The provided name was not a        |
   |                      |       | mechanism name.                    |
   +----------------------+-------+------------------------------------+














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   The following four status codes (DUPLICATE_TOKEN, OLD_TOKEN,
   UNSEQ_TOKEN, and GAP_TOKEN) are contained in a GSSException only if
   detected during context establishment, in which case it is a fatal
   error.  (During per-message calls, these values are indicated as
   supplementary information contained in the MessageProp object.)  They
   are:

   +-----------------+-------+-----------------------------------------+
   | Name            | Value | Meaning                                 |
   +-----------------+-------+-----------------------------------------+
   | DUPLICATE_TOKEN | 19    | The token was a duplicate of an earlier |
   |                 |       | version.                                |
   | OLD_TOKEN       | 20    | The token's validity period has         |
   |                 |       | expired.                                |
   | UNSEQ_TOKEN     | 21    | A later token has already been          |
   |                 |       | processed.                              |
   | GAP_TOKEN       | 22    | The expected token was not received.    |
   +-----------------+-------+-----------------------------------------+

   The GSS major status code of FAILURE is used to indicate that the
   underlying mechanism detected an error for which no specific GSS
   status code is defined.  The mechanism-specific status code can
   provide more details about the error.

   The different major status codes that can be contained in the
   GSSException object thrown by the methods in this specification are
   the same as the major status codes returned by the corresponding
   calls in RFC 2743 [RFC2743].

5.12.2.  Mechanism-Specific Status Codes

   Mechanism-specific status codes are communicated in two ways: they
   are part of any GSSException thrown from the mechanism-specific layer
   to signal a fatal error, or they are part of the MessageProp object
   that the per-message calls use to signal non-fatal errors.

   A default value of 0 in either the GSSException object or the
   MessageProp object will be used to represent the absence of any
   mechanism-specific status code.

5.12.3.  Supplementary Status Codes

   Supplementary status codes are confined to the per-message methods of
   the GSSContext interface.  Because of the informative nature of these
   errors, it is not appropriate to use exceptions to signal them.
   Instead, the per-message operations of the GSSContext interface
   return these values in a MessageProp object.




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   The MessageProp class defines query methods that return boolean
   values indicating the following supplementary states:

   Table: Supplementary Status Methods

   +------------------+------------------------------------------------+
   | Method Name      | Meaning when "true" is returned                |
   +------------------+------------------------------------------------+
   | isDuplicateToken | The token was a duplicate of an earlier token. |
   | isOldToken       | The token's validity period has expired.       |
   | isUnseqToken     | A later token has already been processed.      |
   | isGapToken       | An expected per-message token was not          |
   |                  | received.                                      |
   +------------------+------------------------------------------------+

   A "true" return value for any of the above methods indicates that the
   token exhibited the specified property.  The application MUST
   determine the appropriate course of action for these supplementary
   values.  They are not treated as errors by the GSS-API.

5.13.  Names

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

   Since different authentication mechanisms may employ different
   namespaces for identifying their principals, GSS-API's naming support
   is necessarily complex in multi-mechanism environments (or even in
   some single-mechanism environments where the underlying mechanism
   supports multiple namespaces).

   Two distinct conceptual representations are defined for names:

   1) A GSS-API form represented by implementations of the GSSName
      interface: A single GSSName object MAY contain multiple names from
      different namespaces, but all names SHOULD refer to the same
      entity.  An example of such an internal name would be the name
      returned from a call to the getName method of the GSSCredential
      interface, when applied to a credential containing credential
      elements for multiple authentication mechanisms employing
      different namespaces.  This GSSName object will contain a distinct
      name for the entity for each authentication mechanism.

      For GSS-API implementations supporting multiple namespaces,
      GSSName implementations MUST contain sufficient information to
      determine the namespace to which each primitive name belongs.





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   2) Mechanism-specific contiguous byte array and string forms:
      Different GSSName initialization methods are provided to handle
      both byte array and string formats and to accommodate various
      calling applications and name types.  These formats are capable of
      containing only a single name (from a single namespace).
      Contiguous string names are always accompanied by an Object
      Identifier specifying the namespace to which the name belongs, and
      their format is dependent on the authentication mechanism that
      employs that name.  The string name forms are assumed to be
      printable and may therefore be used by GSS-API applications for
      communication with their users.  The byte array name formats are
      assumed to be in non-printable formats (e.g., the byte array
      returned from the export method of the GSSName interface).

   A GSSName object can be converted to a contiguous representation by
   using the toString method.  This will guarantee that the name will be
   converted to a printable format.  Different initialization methods in
   the GSSName interface are defined to allow support for multiple
   syntaxes for each supported namespace and to allow users the freedom
   to choose a preferred name representation.  The toString method
   SHOULD use an implementation-chosen printable syntax for each
   supported name type.  To obtain the printable name type, the
   getStringNameType method can be used.

   There is no guarantee that calling the toString method on the GSSName
   interface will produce the same string form as the original imported
   string name.  Furthermore, it is possible that the name was not even
   constructed from a string representation.  The same applies to
   namespace identifiers, which may not necessarily survive unchanged
   after a journey through the internal name form.  An example of this
   might be a mechanism that authenticates X.500 names but provides an
   algorithmic mapping of Internet DNS names into X.500.  That
   mechanism's implementation of GSSName might, when presented with a
   DNS name, generate an internal name that contained both the original
   DNS name and the equivalent X.500 name.  Alternatively, it might only
   store the X.500 name.  In the latter case, the toString method of
   GSSName would most likely generate a printable X.500 name, rather
   than the original DNS name.

   The context acceptor can obtain a GSSName object representing the
   entity performing the context initiation (through the usage of the
   getSrcName method).  Since this name has been authenticated by a
   single mechanism, it contains only a single name (even if the
   internal name presented by the context initiator to the GSSContext
   object had multiple components).  Such names are termed internal-
   mechanism names (or MNs), and the names emitted by the GSSContext
   interface's getSrcName and getTargName methods are always of this
   type.  Since some applications may require MNs without wanting to



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   incur the overhead of an authentication operation, creation methods
   are provided that take not only the name buffer and name type but
   also the mechanism OID for which this name should be created.  When
   dealing with an existing GSSName object, the canonicalize method may
   be invoked to convert a general internal name into an MN.

   GSSName objects can be compared using their equal method, which
   returns "true" if the two names being compared refer to the same
   entity.  This is the preferred way to perform name comparisons
   instead of using the printable names that a given GSS-API
   implementation may support.  Since GSS-API assumes that all primitive
   names contained within a given internal name refer to the same
   entity, equal can return "true" if the two names have at least one
   primitive name in common.  If the implementation embodies knowledge
   of equivalence relationships between names taken from different
   namespaces, this knowledge may also allow successful comparisons of
   internal names containing no overlapping primitive elements.
   However, applications SHOULD note that to avoid surprising behavior,
   it is best to ensure that the names being compared are either both
   mechanism names for the same mechanism or both internal names that
   are not mechanism names.  This holds whether the equals method is
   used directly or the export method is used to generate byte strings
   that are then compared byte-by-byte.

   When used in large access control lists, the overhead of creating a
   GSSName object on each name and invoking the equal method on each
   name from the Access Control List (ACL) may be prohibitive.  As an
   alternative way of supporting this case, GSS-API defines a special
   form of the contiguous byte array name, which MAY be compared
   directly (byte by byte).  Contiguous names suitable for comparison
   are generated by the export method.  Exported names MAY be
   re-imported by using the byte array constructor and specifying the
   NT_EXPORT_NAME as the name type Object Identifier.  The resulting
   GSSName name will also be an MN.

   The GSSName interface defines public static Oid objects representing
   the standard name types.  Structurally, an exported name object
   consists of a header containing an OID identifying the mechanism that
   authenticated the name, and a trailer containing the name itself,
   where the syntax of the trailer is defined by the individual
   mechanism specification.  Detailed description of the format is
   specified in the language-independent GSS-API specification
   [RFC2743].

   Note that the results obtained by using the equals method will in
   general be different from those obtained by invoking canonicalize and
   export and then comparing the byte array output.  The first series of
   operation determines whether two (unauthenticated) names identify the



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   same principal; the second determines whether a particular mechanism
   would authenticate them as the same principal.  These two operations
   will in general give the same results only for MNs.

   It is important to note that the above are guidelines as to how
   GSSName implementations SHOULD behave and are not intended to be
   specific requirements of how name objects must be implemented.  The
   mechanism designers are free to decide on the details of their
   implementations of the GSSName interface as long as the behavior
   satisfies the above guidelines.

5.14.  Channel Bindings

   GSS-API supports the use of user-specified tags to identify a given
   context to the peer application.  These tags are intended to be used
   to identify the particular communications channel that carries the
   context.  Channel bindings are communicated to the GSS-API using the
   ChannelBinding object.  The application MAY use byte arrays as well
   as instances of InetAddress to specify the application data to be
   used in the channel binding.  The InetAddress for the initiator and/
   or acceptor can be used within an instance of a ChannelBinding.
   ChannelBinding can be set for the GSSContext object using the
   setChannelBinding method before the first call to init or accept has
   been performed.  Unless the setChannelBinding method has been used to
   set the ChannelBinding for a GSSContext object, "null" ChannelBinding
   will be assumed.  InetAddress is currently the only address type
   defined within the Java platform and as such, it is the only one
   supported within the ChannelBinding class.  Applications that use
   other types of addresses can include them as part of the application-
   specific data.

   Conceptually, the GSS-API concatenates the initiator and acceptor
   address information and the application-supplied byte array to form
   an octet string.  The mechanism calculates a Message Integrity Code
   (MIC) over this octet string and binds the MIC to the context
   establishment token emitted by the init method of the GSSContext
   interface.  The same bindings are set by the context acceptor for its
   GSSContext object, and during processing of the accept method, a MIC
   is calculated in the same way.  The calculated MIC is compared with
   that found in the token, and if the MICs differ, accept will throw a
   GSSException with the major code set to BAD_BINDINGS, and the context
   will not be established.  Some mechanisms may include the actual
   channel-binding data in the token (rather than just a MIC);
   applications SHOULD therefore not use confidential data as channel-
   binding components.






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   Individual mechanisms may impose additional constraints on addresses
   that may appear in channel bindings.  For example, a mechanism may
   verify that the initiator address field of the channel binding
   contains the correct network address of the host system.  Portable
   applications SHOULD therefore ensure that they either provide correct
   information for the address fields or omit the setting of the
   addressing information.

5.15.  Optional Parameters

   Whenever the application wishes to omit an optional parameter, the
   "null" value SHALL be used.  The detailed method descriptions
   indicate which parameters are optional.  Method overloading has also
   been used as a technique to indicate default parameters.

6.  Introduction to GSS-API Classes and Interfaces

   This section presents a brief description of the classes and
   interfaces that constitute the GSS-API.  The implementations of these
   are obtained from the CLASSPATH defined by the application.  If Java
   GSS becomes part of the standard Java APIs, then these classes will
   be available by default on all systems as part of the JRE's system
   classes.

   This section also shows the corresponding RFC 2743 [RFC2743]
   functionality implemented by each of the classes.  Detailed
   description of these classes and their methods is presented in
   Section 7.

6.1.  GSSManager Class

   This abstract class serves as a factory to instantiate
   implementations of the GSS-API interfaces and also provides methods
   to make queries about underlying security mechanisms.

   A default implementation can be obtained using the static method
   getInstance().  Applications that desire to provide their own
   implementation of the GSSManager class can simply extend the abstract
   class themselves.












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   This class contains equivalents of the following RFC 2743 [RFC2743]
   routines:

   +----------------------------+-------------------------+------------+
   | RFC 2743 Routine           | Function                | Section(s) |
   +----------------------------+-------------------------+------------+
   | gss_import_name            | Create an internal name | 7.1.5 -    |
   |                            | from the supplied       | 7.1.8      |
   |                            | information.            |            |
   | gss_acquire_cred           | Acquire credential for  | 7.1.9 -    |
   |                            | use.                    | 7.1.11     |
   | gss_import_sec_context     | Create a previously     | 7.1.14     |
   |                            | exported context.       |            |
   | gss_indicate_mechs         | List the mechanisms     | 7.1.2      |
   |                            | supported by this GSS-  |            |
   |                            | API implementation.     |            |
   | gss_inquire_mechs_for_name | List the mechanisms     | 7.1.4      |
   |                            | supporting the          |            |
   |                            | specified name type.    |            |
   | gss_inquire_names_for_mech | List the name types     | 7.1.3      |
   |                            | supported by the        |            |
   |                            | specified mechanism.    |            |
   +----------------------------+-------------------------+------------+

6.2.  GSSName Interface

   GSS-API names are represented in the Java bindings through the
   GSSName interface.  Different name formats and their definitions are
   identified with Universal OIDs.  The format of the names can be
   derived based on the unique OID of each name type.  The following
   GSS-API routines are provided by the GSSName interface:




















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   +-----------------------+------------------------------+------------+
   | RFC 2743 Routine      | Function                     | Section(s) |
   +-----------------------+------------------------------+------------+
   | gss_display_name      | Convert internal name        | 7.2.6      |
   |                       | representation to text       |            |
   |                       | format.                      |            |
   | gss_compare_name      | Compare two internal names.  | 7.2.2,     |
   |                       |                              | 7.2.3      |
   | gss_release_name      | Release resources associated | N/A        |
   |                       | with the internal name.      |            |
   | gss_canonicalize_name | Convert an internal name to  | 7.2.4      |
   |                       | a mechanism name.            |            |
   | gss_export_name       | Convert a mechanism name to  | 7.2.5      |
   |                       | export format.               |            |
   | gss_duplicate_name    | Create a copy of the         | N/A        |
   |                       | internal name.               |            |
   +-----------------------+------------------------------+------------+

   The gss_release_name call is not provided as Java does its own
   garbage collection.  The gss_duplicate_name call is also redundant;
   the GSSName interface has no mutator methods that can change the
   state of the object, so it is safe for sharing across threads.

6.3.  GSSCredential Interface

   The GSSCredential interface is responsible for the encapsulation of
   GSS-API credentials.  Credentials identify a single entity and
   provide the necessary cryptographic information to enable the
   creation of a context on behalf of that entity.  A single credential
   may contain multiple mechanism-specific credentials, each referred to
   as a credential element.  The GSSCredential interface provides the
   functionality of the following GSS-API routines:

   +--------------------------+---------------------------+------------+
   | RFC 2743 Routine         | Function                  | Section(s) |
   +--------------------------+---------------------------+------------+
   | gss_add_cred             | Constructs credentials    | 7.3.11     |
   |                          | incrementally.            |            |
   | gss_inquire_cred         | Obtain information about  | 7.3.3 -    |
   |                          | credential.               | 7.3.10     |
   | gss_inquire_cred_by_mech | Obtain per-mechanism      | 7.3.4 -    |
   |                          | information about a       | 7.3.9      |
   |                          | credential.               |            |
   | gss_release_cred         | Dispose of credentials    | 7.3.2      |
   |                          | after use.                |            |
   +--------------------------+---------------------------+------------+





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6.4.  GSSContext Interface

   This interface encapsulates the functionality of context-level calls
   required for security context establishment and management between
   peers as well as the per-message services offered to applications.  A
   context is established between a pair of peers and allows the usage
   of security services on a per-message basis on application data.  It
   is created over a single security mechanism.  The GSSContext
   interface provides the functionality of the following GSS-API
   routines:

   +------------------------+-----------------------------+------------+
   | RFC 2743 Routine       | Function                    | Section(s) |
   +------------------------+-----------------------------+------------+
   | gss_init_sec_context   | Initiate the creation of a  | 7.4.2      |
   |                        | security context with a     |            |
   |                        | peer.                       |            |
   | gss_accept_sec_context | Accept a security context   | 7.4.3      |
   |                        | initiated by a peer.        |            |
   | gss_delete_sec_context | Destroy a security context. | 7.4.5      |
   | gss_context_time       | Obtain remaining context    | 7.4.30     |
   |                        | time.                       |            |
   | gss_inquire_context    | Obtain context              | 7.4.21 -   |
   |                        | characteristics.            | 7.4.35     |
   | gss_wrap_size_limit    | Determine token-size limit  | 7.4.6      |
   |                        | for gss_wrap.               |            |
   | gss_export_sec_context | Transfer security context   | 7.4.11     |
   |                        | to another process.         |            |
   | gss_get_mic            | Calculate a cryptographic   | 7.4.9      |
   |                        | Message Integrity Code      |            |
   |                        | (MIC) for a message.        |            |
   | gss_verify_mic         | Verify integrity on a       | 7.4.10     |
   |                        | received message.           |            |
   | gss_wrap               | Attach a MIC to a message   | 7.4.7      |
   |                        | and optionally encrypt the  |            |
   |                        | message content.            |            |
   | gss_unwrap             | Obtain a previously wrapped | 7.4.8      |
   |                        | application message         |            |
   |                        | verifying its integrity and |            |
   |                        | optionally decrypting it.   |            |
   +------------------------+-----------------------------+------------+

   The functionality offered by the gss_process_context_token routine
   has not been included in the Java bindings specification.  The
   corresponding functionality of gss_delete_sec_context has also been
   modified to not return any peer tokens.  This has been proposed in





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   accordance to the recommendations stated in RFC 2743 [RFC2743].
   GSSContext does offer the functionality of destroying the locally
   stored context information.

6.5.  MessageProp Class

   This helper class is used in the per-message operations on the
   context.  An instance of this class is created by the application and
   then passed into the per-message calls.  In some cases, the
   application conveys information to the GSS-API implementation through
   this object, and in other cases, the GSS-API returns information to
   the application by setting it in this object.  See the description of
   the per-message operations wrap, unwrap, getMIC, and verifyMIC in the
   GSSContext interfaces for details.

6.6.  GSSException Class

   Exceptions are used in the Java bindings to signal fatal errors to
   the calling applications.  This replaces the major and minor codes
   used in the C-bindings specification as a method of signaling
   failures.  The GSSException class handles both minor and major codes,
   as well as their translation into textual representation.  All
   GSS-API methods are declared as throwing this exception.

   +--------------------+----------------------------+-----------------+
   | RFC 2743 Routine   | Function                   | Section         |
   +--------------------+----------------------------+-----------------+
   | gss_display_status | Retrieve textual           | 7.8.5, 7.8.6,   |
   |                    | representation of error    | 7.8.9, 7.8.10   |
   |                    | codes.                     |                 |
   +--------------------+----------------------------+-----------------+

6.7.  Oid Class

   This utility class is used to represent Universal Object Identifiers
   and their associated operations.  GSS-API uses Object Identifiers to
   distinguish between security mechanisms and name types.  This class,
   aside from being used whenever an Object Identifier is needed,
   implements the following GSS-API functionality:

   +-------------------------+-------------------------------+---------+
   | RFC 2743 Routine        | Function                      | Section |
   +-------------------------+-------------------------------+---------+
   | gss_test_oid_set_member | Determine if the specified    | 7.7.5   |
   |                         | OID is part of a set of OIDs. |         |
   +-------------------------+-------------------------------+---------+





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6.8.  ChannelBinding Class

   An instance of this class is used to specify channel-binding
   information to the GSSContext object before the start of a security
   context establishment.  The application may use a byte array to
   specify application data to be used in the channel binding as well as
   to use instances of the InetAddress.  InetAddress is currently the
   only address type defined within the Java platform and as such, it is
   the only one supported within the ChannelBinding class.  Applications
   that use other types of addresses can include them as part of the
   application data.

7.  Detailed GSS-API Class Description

   This section lists a detailed description of all the public methods
   that each of the GSS-API classes and interfaces MUST provide.

7.1.  public abstract class GSSManager

   The GSSManager class is an abstract class that serves as a factory
   for three GSS interfaces: GSSName, GSSCredential, and GSSContext.  It
   also provides methods for applications to determine what mechanisms
   are available from the GSS implementation and what name types these
   mechanisms support.  An instance of the default GSSManager subclass
   MAY be obtained through the static method getInstance(), but
   applications are free to instantiate other subclasses of GSSManager.

   All but one method in this class are declared abstract.  This means
   that subclasses have to provide the complete implementation for those
   methods.  The only exception to this is the static method
   getInstance(), which will have platform-specific code to return an
   instance of the default subclass.

   Platform providers of GSS are REQUIRED not to add any constructors to
   this class, whether the constructor is private, public, or protected.
   This will ensure that all subclasses invoke only the default
   constructor provided to the base class by the compiler.

   A subclass extending the GSSManager abstract class MAY be implemented
   as a modular provider-based layer that utilizes some well-known
   service provider specification.  The GSSManager API provides the
   application with methods to set provider preferences on such an
   implementation.  These methods also allow the implementation to throw
   a well-defined exception in case provider-based configuration is not
   supported.  Applications that expect to be portable SHOULD be aware
   of this and recover cleanly by catching the exception.





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   It is envisioned that there will be three most common ways in which
   providers will be used:

   1) The application does not care about what provider is used (the
      default case).

   2) The application wants a particular provider to be used
      preferentially, either for a particular mechanism or all the time,
      irrespective of the mechanism.

   3) The application wants to use the locally configured providers as
      far as possible, but if support is missing for one or more
      mechanisms, then it wants to fall back on its own provider.

   The GSSManager class has two methods that enable these modes of
   usage: addProviderAtFront() and addProviderAtEnd().  These methods
   have the effect of creating an ordered list of <provider, OID> pairs
   where each pair indicates a preference of provider for a given OID.

   The use of these methods does not require any knowledge of whatever
   service provider specification the GSSManager subclass follows.  It
   is hoped that these methods will serve the needs of most
   applications.  Additional methods MAY be added to an extended
   GSSManager that could be part of a service provider specification
   that is standardized later.

   When neither of the methods is called, the implementation SHOULD
   choose a default provider for each mechanism it supports.

7.1.1.  getInstance

   public static GSSManager getInstance()

   Returns the default GSSManager implementation.

7.1.2.  getMechs

   public abstract Oid[] getMechs()

   Returns an array of Oid objects indicating the mechanisms available
   to GSS-API callers.  A "null" value is returned when no mechanisms
   are available (an example of this would be when mechanisms are
   dynamically configured, and currently no mechanisms are installed).








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7.1.3.  getNamesForMech

   public abstract Oid[] getNamesForMech(Oid mech)
                         throws GSSException

   Returns name type OIDs supported by the specified mechanism.

   Parameters:

   mech                The Oid object for the mechanism to query.

7.1.4.  getMechsForName

   public abstract Oid[] getMechsForName(Oid nameType)

   Returns an array of Oid objects corresponding to the mechanisms that
   support the specific name type. "null" is returned when no mechanisms
   are found to support the specified name type.

   Parameters:

   nameType            The Oid object for the name type.

7.1.5.  createName

   public abstract GSSName createName(String nameStr, Oid nameType)
                   throws GSSException

   Factory method to convert a contiguous string name from the specified
   namespace to a GSSName object.  In general, the GSSName object
   created will not be an MN; two examples that are exceptions to this
   are when the namespace type parameter indicates NT_EXPORT_NAME or
   when the GSS-API implementation does not support multiple mechanisms.

   Parameters:

   nameStr             The string representing a printable form of the
                       name to create.

   nameType            The OID specifying the namespace of the printable
                       name is supplied.  Note that nameType serves to
                       describe and qualify the interpretation of the
                       input nameStr; it does not necessarily imply a
                       type for the output GSSName implementation.  The
                       "null" value can be used to specify that a
                       mechanism-specific default printable syntax
                       SHOULD be assumed by each mechanism that examines
                       nameStr.



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7.1.6.  createName

   public abstract GSSName createName(byte[] name, Oid nameType)
                   throws GSSException

   Factory method to convert a contiguous byte array containing a name
   from the specified namespace to a GSSName object.  In general, the
   GSSName object created will not be an MN; two examples that are
   exceptions to this are when the namespace type parameter indicates
   NT_EXPORT_NAME or when the GSS-API implementation is not a multi-
   mechanism.

   Parameters:

   name                The byte array containing the name to create.

   nameType            The OID specifying the namespace of the name
                       supplied in the byte array.  Note that nameType
                       serves to describe and qualify the interpretation
                       of the input name byte array; it does not
                       necessarily imply a type for the output GSSName
                       implementation.  The "null" value can be used to
                       specify that a mechanism-specific default syntax
                       SHOULD be assumed by each mechanism that examines
                       the byte array.

7.1.7.  createName

   public abstract GSSName createName(String nameStr, Oid nameType,
                   Oid mech) throws GSSException

   Factory method to convert a contiguous string name from the specified
   namespace to a GSSName object that is a mechanism name (MN).  In
   other words, this method is a utility that does the equivalent of two
   steps: the createName described in Section 7.1.5 and also the
   GSSName.canonicalize() described in Section 7.2.4.

   Parameters:

   nameStr             The string representing a printable form of the
                       name to create.










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   nameType            The OID specifying the namespace of the printable
                       name supplied.  Note that nameType serves to
                       describe and qualify the interpretation of the
                       input nameStr; it does not necessarily imply a
                       type for the output GSSName implementation.  The
                       "null" value can be used to specify that a
                       mechanism-specific default printable syntax
                       SHOULD be assumed when the mechanism examines
                       nameStr.

   mech                OID specifying the mechanism for which this name
                       should be created.

7.1.8.  createName

   public abstract GSSName createName(byte[] name, Oid nameType,
                   Oid mech) throws GSSException

   Factory method to convert a contiguous byte array containing a name
   from the specified namespace to a GSSName object that is an MN.  In
   other words, this method is a utility that does the equivalent of two
   steps: the createName described in Section 7.1.6 and also the
   GSSName.canonicalize() described in Section 7.2.4.

   Parameters:

   name                The byte array representing the name to create.

   nameType            The OID specifying the namespace of the name
                       supplied in the byte array.  Note that nameType
                       serves to describe and qualify the interpretation
                       of the input name byte array; it does not
                       necessarily imply a type for the output GSSName
                       implementation.  The "null" value can be used to
                       specify that a mechanism-specific default syntax
                       SHOULD be assumed by each mechanism that examines
                       the byte array.

   mech                OID specifying the mechanism for which this name
                       should be created.











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7.1.9.  createCredential

   public abstract GSSCredential createCredential(int usage)
                   throws GSSException

   Factory method for acquiring default credentials.  This will cause
   the GSS-API to use system-specific defaults for the set of
   mechanisms, name, and a DEFAULT lifetime.

   Parameters:

   usage               The intended usage for this credential object.
                       The value of this parameter MUST be one of:

                       GSSCredential.INITIATE_AND_ACCEPT(0),
                       GSSCredential.INITIATE_ONLY(1), or
                       GSSCredential.ACCEPT_ONLY(2)

7.1.10.  createCredential

   public abstract GSSCredential createCredential(GSSName aName,
                   int lifetime, Oid mech, int usage)
                   throws GSSException

   Factory method for acquiring a single-mechanism credential.

   Parameters:

   aName               Name of the principal for whom this credential is
                       to be acquired.  Use "null" to specify the
                       default principal.

   lifetime            The number of seconds that credentials should
                       remain valid.  Use
                       GSSCredential.INDEFINITE_LIFETIME to request that
                       the credentials have the maximum permitted
                       lifetime.  Use GSSCredential.DEFAULT_LIFETIME to
                       request default credential lifetime.

   mech                The OID of the desired mechanism.  Use "(Oid)
                       null" to request the default mechanism.

   usage               The intended usage for this credential object.
                       The value of this parameter MUST be one of:

                       GSSCredential.INITIATE_AND_ACCEPT(0),
                       GSSCredential.INITIATE_ONLY(1), or
                       GSSCredential.ACCEPT_ONLY(2)



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7.1.11.  createCredential

   public abstract GSSCredential createCredential(GSSName aName,
                   int lifetime, Oid[] mechs, int usage)
                   throws GSSException

   Factory method for acquiring credentials over a set of mechanisms.
   Acquires credentials for each of the mechanisms specified in the
   array called mechs.  To determine the list of mechanisms for which
   the acquisition of credentials succeeded, the caller should use the
   GSSCredential.getMechs() method.

   Parameters:

   aName               Name of the principal for whom this credential is
                       to be acquired.  Use "null" to specify the
                       default principal.

   lifetime            The number of seconds that credentials should
                       remain valid.  Use
                       GSSCredential.INDEFINITE_LIFETIME to request that
                       the credentials have the maximum permitted
                       lifetime.  Use GSSCredential.DEFAULT_LIFETIME to
                       request default credential lifetime.

   mechs               The array of mechanisms over which the credential
                       is to be acquired.  Use "(Oid[]) null" for
                       requesting a system-specific default set of
                       mechanisms.

   usage               The intended usage for this credential object.
                       The value of this parameter MUST be one of:

                       GSSCredential.INITIATE_AND_ACCEPT(0),
                       GSSCredential.INITIATE_ONLY(1), or
                       GSSCredential.ACCEPT_ONLY(2)

7.1.12.  createContext

   public abstract GSSContext createContext(GSSName peer, Oid mech,
                   GSSCredential myCred, int lifetime)
                   throws GSSException

   Factory method for creating a context on the initiator's side.
   Context flags may be modified through the mutator methods prior to
   calling GSSContext.initSecContext().





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   Parameters:

   peer                Name of the target peer.

   mech                OID of the desired mechanism.  Use "(Oid) null"
                       to request the default mechanism.

   myCred              Credentials of the initiator.  Use "null" to act
                       as a default initiator principal.

   lifetime            The request lifetime, in seconds, for the
                       context.  Use GSSContext.INDEFINITE_LIFETIME and
                       GSSContext.DEFAULT_LIFETIME to request indefinite
                       or default context lifetime.

7.1.13.  createContext

   public abstract GSSContext createContext(GSSCredential myCred)
                   throws GSSException

   Factory method for creating a context on the acceptor's side.  The
   context's properties will be determined from the input token supplied
   to the accept method.

   Parameters:

   myCred              Credentials for the acceptor.  Use "null" to act
                       as a default acceptor principal.

7.1.14.  createContext

   public abstract GSSContext createContext(byte[] interProcessToken)
                   throws GSSException

   Factory method for importing a previously exported context.  The
   context properties will be determined from the input token and can't
   be modified through the set methods.

   Parameters:

   interProcessToken   The token previously emitted from the export
                       method.









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7.1.15.  addProviderAtFront

   public abstract void addProviderAtFront(Provider p, Oid mech)
                   throws GSSException

   This method is used to indicate to the GSSManager that the
   application would like a particular provider to be used ahead of all
   others when support is desired for the given mechanism.  When a value
   of "null" is used instead of an Oid object for the mechanism, the
   GSSManager MUST use the indicated provider ahead of all others no
   matter what the mechanism is.  Only when the indicated provider does
   not support the needed mechanism should the GSSManager move on to a
   different provider.

   Calling this method repeatedly preserves the older settings but
   lowers them in preference thus forming an ordered list of provider
   and OID pairs that grows at the top.

   Calling addProviderAtFront with a null Oid will remove all previous
   preferences that were set for this provider in the GSSManager
   instance.  Calling addProviderAtFront with a non-null Oid will remove
   any previous preference that was set using this mechanism and this
   provider together.

   If the GSSManager implementation does not support an SPI with a
   pluggable provider architecture, it SHOULD throw a GSSException with
   the status code GSSException.UNAVAILABLE to indicate that the
   operation is unavailable.

   Parameters:

   p                   The provider instance that should be used
                       whenever support is needed for mech.

   mech                The mechanism for which the provider is being
                       set.















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7.1.15.1.  addProviderAtFront Example Code

   Suppose an application desired that provider A always be checked
   first when any mechanism is needed, it would call:

   <CODE BEGINS>
   GSSManager mgr = GSSManager.getInstance();
   // mgr may at this point have its own pre-configured list
   // of provider preferences.  The following will prepend to
   // any such list:

   mgr.addProviderAtFront(A, null);
   <CODE ENDS>

   Now if it also desired that the mechanism of OID m1 always be
   obtained from provider B before the previous set A was checked, it
   would call:

   <CODE BEGINS>
   mgr.addProviderAtFront(B, m1);
   <CODE ENDS>

   The GSSManager would then first check with B if m1 was needed.  In
   case B did not provide support for m1, the GSSManager would continue
   on to check with A.  If any mechanism m2 is needed where m2 is
   different from m1, then the GSSManager would skip B and check with A
   directly.

   Suppose, at a later time, the following call is made to the same
   GSSManager instance:

   <CODE BEGINS>
   mgr.addProviderAtFront(B, null)
   <CODE ENDS>

   then the previous setting with the pair (B, m1) is subsumed by this
   and SHOULD be removed.  Effectively, the list of preferences now
   becomes {(B, null), (A, null), ... //followed by the pre-configured
   list}.

   Please note, however, that the following call:

   <CODE BEGINS>
   mgr.addProviderAtFront(A, m3)
   <CODE ENDS>

   does not subsume the previous setting of (A, null), and the list will
   effectively become {(A, m3), (B, null), (A, null), ...}



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7.1.16.  addProviderAtEnd

   public abstract void addProviderAtEnd(Provider p, Oid mech)
                   throws GSSException

   This method is used to indicate to the GSSManager that the
   application would like a particular provider to be used if no other
   provider can be found that supports the given mechanism.  When a
   value of "null" is used instead of an Oid object for the mechanism,
   the GSSManager MUST use the indicated provider for any mechanism.

   Calling this method repeatedly preserves the older settings but
   raises them above newer ones in preference, thus forming an ordered
   list of providers and OID pairs that grows at the bottom.  Thus, the
   older provider settings will be utilized first before this one is.

   If there are any previously existing preferences that conflict with
   the preference being set here, then the GSSManager SHOULD ignore this
   request.

   If the GSSManager implementation does not support an SPI with a
   pluggable provider architecture, it SHOULD throw a GSSException with
   the status code GSSException.UNAVAILABLE to indicate that the
   operation is unavailable.

   Parameters:

   p                   The provider instance that should be used
                       whenever support is needed for mech.

   mech                The mechanism for which the provider is being
                       set.

7.1.16.1.  addProviderAtEnd Example Code

   Suppose an application desired that when a mechanism of OID m1 is
   needed, the system default providers always be checked first, and
   only when they do not support m1 should a provider A be checked.  It
   would then make the call:

   <CODE BEGINS>
   GSSManager mgr = GSSManager.getInstance();

   mgr.addProviderAtEnd(A, m1);
   <CODE ENDS>






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   Now, if it also desired that provider B be checked for all mechanisms
   after all configured providers have been checked, it would then call:

   <CODE BEGINS>
   mgr.addProviderAtEnd(B, null);
   <CODE ENDS>

   Effectively, the list of preferences now becomes {..., (A, m1), (B,
   null)}.

   Suppose, at a later time, the following call is made to the same
   GSSManager instance:

   <CODE BEGINS>
   mgr.addProviderAtEnd(B, m2)
   <CODE ENDS>

   then the previous setting with the pair (B, null) subsumes this;
   therefore, this request SHOULD be ignored.  The same would happen if
   a request is made for the already existing pairs of (A, m1) or (B,
   null).

   Please note, however, that the following call:

   <CODE BEGINS>
   mgr.addProviderAtEnd(A, null)
   <CODE ENDS>

   is not subsumed by the previous setting of (A, m1), and the list will
   effectively become {..., (A, m1), (B, null), (A, null)}.

7.1.17.  Example Code

   <CODE BEGINS>
   GSSManager mgr = GSSManager.getInstance();

   // What mechs are available to us?

   Oid[] supportedMechs = mgr.getMechs();

   // Set a preference for the provider to be used when support
   // is needed for the mechanisms:
   //  "1.2.840.113554.1.2.2" and "1.3.6.1.5.5.1.1".

   Oid krb = new Oid("1.2.840.113554.1.2.2");
   Oid spkm1 = new Oid("1.3.6.1.5.5.1.1");

   Provider p = (Provider) (new com.foo.security.Provider());



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   mgr.addProviderAtFront(p, krb);
   mgr.addProviderAtFront(p, spkm1);

   // What name types does this spkm implementation support?
   Oid[] nameTypes = mgr.getNamesForMech(spkm1);
   <CODE ENDS>

7.2.  public interface GSSName

   This interface encapsulates a single GSS-API principal entity.
   Different name formats and their definitions are identified with
   Universal OIDs.  The format of the names can be derived based on the
   unique OID of its namespace type.

7.2.1.  Static Constants

   public static final Oid NT_HOSTBASED_SERVICE

   OID indicating a host-based service name form.  It is used to
   represent services associated with host computers.  This name form is
   constructed using two elements, "service" and "hostname", as follows:

      service@hostname

   Values for the "service" element are registered with the IANA.  It
   represents the following value: { iso(1) member-body(2) United
   States(840) mit(113554) infosys(1) gssapi(2) generic(1)
   service_name(4) }

   public static final Oid NT_USER_NAME

   Name type to indicate a named user on a local system.  It represents
   the following value: { iso(1) member-body(2) United States(840)
   mit(113554) infosys(1) gssapi(2) generic(1) user_name(1) }

   public static final Oid NT_MACHINE_UID_NAME

   Name type to indicate a numeric user identifier corresponding to a
   user on a local system (e.g., Uid).  It represents the following
   value: { iso(1) member-body(2) United States(840) mit(113554)
   infosys(1) gssapi(2) generic(1) machine_uid_name(2) }

   public static final Oid NT_STRING_UID_NAME

   Name type to indicate a string of digits representing the numeric
   user identifier of a user on a local system.  It represents the
   following value: { iso(1) member-body(2) United States(840)
   mit(113554) infosys(1) gssapi(2) generic(1) string_uid_name(3) }



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   public static final Oid NT_ANONYMOUS

   Name type for representing an anonymous entity.  It represents the
   following value: { iso(1), org(3), dod(6), internet(1), security(5),
   nametypes(6), gss-anonymous-name(3) }

   public static final Oid NT_EXPORT_NAME

   Name type used to indicate an exported name produced by the export
   method.  It represents the following value: { iso(1), org(3), dod(6),
   internet(1), security(5), nametypes(6), gss-api-exported-name(4) }

7.2.2.  equals

   public boolean equals(GSSName another) throws GSSException

   Compares two GSSName objects to determine whether they refer to the
   same entity.  This method MAY throw a GSSException when the names
   cannot be compared.  If either of the names represents an anonymous
   entity, the method will return "false".

   Parameters:

   another             GSSName object with which to compare.

7.2.3.  equals

   public boolean equals(Object another)

   A variation of the equals method, described in Section 7.2.2, that is
   provided to override the Object.equals() method that the implementing
   class will inherit.  The behavior is exactly the same as that in
   Section 7.2.2 except that no GSSException is thrown; instead, "false"
   will be returned in the situation where an error occurs.  (Note that
   the Java language specification requires that two objects that are
   equal according to the equals(Object) method MUST return the same
   integer result when the hashCode() method is called on them.)

   Parameters:

   another             GSSName object with which to compare.










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7.2.4.  canonicalize

   public GSSName canonicalize(Oid mech) throws GSSException

   Creates an MN from an arbitrary internal name.  This is equivalent to
   using the factory methods described in Sections 7.1.7 or 7.1.8 that
   take the mechanism name as one of their parameters.

   Parameters:

   mech                The OID for the mechanism for which the canonical
                       form of the name is requested.

7.2.5.  export

   public byte[] export() throws GSSException

   Returns a canonical contiguous byte representation of an MN, suitable
   for direct, byte-by-byte comparison by authorization functions.  If
   the name is not an MN, implementations MAY throw a GSSException with
   the NAME_NOT_MN status code.  If an implementation chooses not to
   throw an exception, it SHOULD use some system-specific default
   mechanism to canonicalize the name and then export it.  The format of
   the header of the output buffer is specified in RFC 2743 [RFC2743].

7.2.6.  toString

   public String toString()

   Returns a textual representation of the GSSName object.  To retrieve
   the printed name format, which determines the syntax of the returned
   string, the getStringNameType method can be used.

7.2.7.  getStringNameType

   public Oid getStringNameType() throws GSSException

   Returns the OID representing the type of name returned through the
   toString method.  Using this OID, the syntax of the printable name
   can be determined.

7.2.8.  isAnonymous

   public boolean isAnonymous()

   Tests if this name object represents an anonymous entity.  Returns
   "true" if this is an anonymous name.




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7.2.9.  isMN

   public boolean isMN()

   Tests if this name object contains only one mechanism element and is
   thus a mechanism name as defined by RFC 2743 [RFC2743].

7.2.10.  Example Code

   Included below are code examples utilizing the GSSName interface.
   The code below creates a GSSName, converts it to an MN, performs a
   comparison, obtains a printable representation of the name, exports
   it, and then re-imports to obtain a new GSSName.

   <CODE BEGINS>
   GSSManager mgr = GSSManager.getInstance();

   // create a host-based service name
   GSSName name = mgr.createName("service@host",
                   GSSName.NT_HOSTBASED_SERVICE);

   Oid krb5 = new Oid("1.2.840.113554.1.2.2");

   GSSName mechName = name.canonicalize(krb5);

   // the above two steps are equivalent to the following
   GSSName mechName = mgr.createName("service@host",
                   GSSName.NT_HOSTBASED_SERVICE, krb5);

   // perform name comparison
   if (name.equals(mechName))
           print("Names are equals.");

   // obtain textual representation of name and its printable
   // name type
   print(mechName.toString() +
         mechName.getStringNameType().toString());

   // export the name
   byte[] exportName = mechName.export();

   // create a new name object from the exported buffer
   GSSName newName = mgr.createName(exportName,
                     GSSName.NT_EXPORT_NAME);
   <CODE ENDS>






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7.3.  public interface GSSCredential implements Cloneable

   This interface encapsulates the GSS-API credentials for an entity.  A
   credential contains all the necessary cryptographic information to
   enable the creation of a context on behalf of the entity that it
   represents.  It MAY contain multiple, distinct, mechanism-specific
   credential elements, each containing information for a specific
   security mechanism, but all referring to the same entity.

   A credential MAY be used to perform context initiation, acceptance,
   or both.

   GSS-API implementations MUST impose a local access-control policy on
   callers to prevent unauthorized callers from acquiring credentials to
   which they are not entitled.  GSS-API credential creation is not
   intended to provide a "login to the network" function, as such a
   function would involve the creation of new credentials rather than
   merely acquiring a handle to existing credentials.  Such functions,
   if required, SHOULD be defined in implementation-specific extensions
   to the API.

   If credential acquisition is time-consuming for a mechanism, the
   mechanism MAY choose to delay the actual acquisition until the
   credential is required (e.g., by GSSContext).  Such mechanism-
   specific implementation decisions SHOULD be invisible to the calling
   application; thus, the query methods immediately following the
   creation of a credential object MUST return valid credential data and
   may therefore incur the overhead of a deferred credential
   acquisition.

   Applications will create a credential object passing the desired
   parameters.  The application can then use the query methods to obtain
   specific information about the instantiated credential object
   (equivalent to the gss_inquire routines).  When the credential is no
   longer needed, the application SHOULD call the dispose (equivalent to
   gss_release_cred) method to release any resources held by the
   credential object and to destroy any cryptographically sensitive
   information.

   Classes implementing this interface also implement the Cloneable
   interface.  This indicates that the class will support the clone()
   method that will allow the creation of duplicate credentials.  This
   is useful when called just before the add() call to retain a copy of
   the original credential.







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7.3.1.  Static Constants

   public static final int INITIATE_AND_ACCEPT

   Credential usage flag requesting that it be able to be used for both
   context initiation and acceptance.  The value of this constant is 0.

   public static final int INITIATE_ONLY

   Credential usage flag requesting that it be able to be used for
   context initiation only.  The value of this constant is 1.

   public static final int ACCEPT_ONLY

   Credential usage flag requesting that it be able to be used for
   context acceptance only.  The value of this constant is 2.

   public static final int DEFAULT_LIFETIME

   A lifetime constant representing the default credential lifetime.
   The value of this constant is 0.

   public static final int INDEFINITE_LIFETIME

   A lifetime constant representing indefinite credential lifetime.  The
   value of this constant is the maximum integer value in Java --
   Integer.MAX_VALUE.

7.3.2.  dispose

   public void dispose() throws GSSException

   Releases any sensitive information that the GSSCredential object may
   be containing.  Applications SHOULD call this method as soon as the
   credential is no longer needed to minimize the time any sensitive
   information is maintained.

7.3.3.  getName

   public GSSName getName() throws GSSException

   Retrieves the name of the entity that the credential asserts.









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7.3.4.  getName

   public GSSName getName(Oid mechOID) throws GSSException

   Retrieves a mechanism name of the entity that the credential asserts.
   Equivalent to calling canonicalize() on the name returned by
   Section 7.3.3.

   Parameters:

   mechOID             The mechanism for which information should be
                       returned.

7.3.5.  getRemainingLifetime

   public int getRemainingLifetime() throws GSSException

   Returns the remaining lifetime in seconds for a credential.  The
   remaining lifetime is the minimum lifetime for any of the underlying
   credential mechanisms.  A return value of
   GSSCredential.INDEFINITE_LIFETIME indicates that the credential does
   not expire.  A return value of 0 indicates that the credential is
   already expired.

7.3.6.  getRemainingInitLifetime

   public int getRemainingInitLifetime(Oid mech) throws GSSException

   Returns the remaining lifetime in seconds for the credential to
   remain capable of initiating security contexts under the specified
   mechanism.  A return value of GSSCredential.INDEFINITE_LIFETIME
   indicates that the credential does not expire for context initiation.
   A return value of 0 indicates that the credential is already expired.

   Parameters:

   mechOID             The mechanism for which information should be
                       returned.

7.3.7.  getRemainingAcceptLifetime

   public int getRemainingAcceptLifetime(Oid mech) throws GSSException

   Returns the remaining lifetime in seconds for the credential to
   remain capable of accepting security contexts under the specified
   mechanism.  A return value of GSSCredential.INDEFINITE_LIFETIME
   indicates that the credential does not expire for context acceptance.
   A return value of 0 indicates that the credential is already expired.



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   Parameters:

   mechOID             The mechanism for which information should be
                       returned.

7.3.8.  getUsage

   public int getUsage() throws GSSException

   Returns the credential usage flag as a union over all mechanisms.
   The return value will be one of GSSCredential.INITIATE_AND_ACCEPT(0),
   GSSCredential.INITIATE_ONLY(1), or GSSCredential.ACCEPT_ONLY(2).

   Specifically, GSSCredential.INITIATE_AND_ACCEPT(0) SHOULD be returned
   as long as there exists one credential element allowing context
   initiation and one credential element allowing context acceptance.
   These two credential elements are not necessarily the same one, nor
   do they need to use the same mechanism(s).

7.3.9.  getUsage

   public int getUsage(Oid mechOID) throws GSSException

   Returns the credential usage flag for the specified mechanism only.
   The return value will be one of GSSCredential.INITIATE_AND_ACCEPT(0),
   GSSCredential.INITIATE_ONLY(1), or GSSCredential.ACCEPT_ONLY(2).

   Parameters:

   mechOID             The mechanism for which information should be
                       returned.

7.3.10.  getMechs

   public Oid[] getMechs() throws GSSException

   Returns an array of mechanisms supported by this credential.

7.3.11.  add

   public void add(GSSName aName, int initLifetime, int acceptLifetime,
                   Oid mech, int usage) throws GSSException

   Adds a mechanism-specific credential element to an existing
   credential.  This method allows the construction of credentials one
   mechanism at a time.





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   This routine is envisioned to be used mainly by context acceptors
   during the creation of acceptance credentials, which are to be used
   with a variety of clients using different security mechanisms.

   This routine adds the new credential element "in-place".  To add the
   element in a new credential, first call clone() to obtain a copy of
   this credential, then call its add() method.

   Parameters:

   aName               Name of the principal for whom this credential is
                       to be acquired.  Use "null" to specify the
                       default principal.

   initLifetime        The number of seconds that credentials should
                       remain valid for initiating security contexts.
                       Use GSSCredential.INDEFINITE_LIFETIME to request
                       that the credentials have the maximum permitted
                       lifetime.  Use GSSCredential.DEFAULT_LIFETIME to
                       request default credential lifetime.

   acceptLifetime      The number of seconds that credentials should
                       remain valid for accepting security contexts.

                       Use GSSCredential.INDEFINITE_LIFETIME to request
                       that the credentials
                       have the maximum permitted lifetime.  Use
                       GSSCredential.DEFAULT_LIFETIME to request default
                       credential lifetime.

   mech                The mechanisms over which the credential is to be
                       acquired.

   usage               The intended usage for this credential object.
                       The value of this parameter MUST be one of:

                       GSSCredential.INITIATE_AND_ACCEPT(0),
                       GSSCredential.INITIATE_ONLY(1), or
                       GSSCredential.ACCEPT_ONLY(2)

7.3.12.  equals

   public boolean equals(Object another)

   Tests if this GSSCredential refers to the same entity as the supplied
   object.  The two credentials MUST be acquired over the same
   mechanisms and MUST refer to the same principal.  Returns "true" if
   the two GSSCredentials refer to the same entity, or "false"



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   otherwise.  (Note that the Java language specification [JLS] requires
   that two objects that are equal according to the equals(Object)
   method MUST return the same integer result when the hashCode() method
   is called on them.)

   Parameters:

   another             Another GSSCredential object for comparison.

7.3.13.  Example Code

   This example code demonstrates the creation of a GSSCredential
   implementation for a specific entity, querying of its fields, and its
   release when it is no longer needed.

   <CODE BEGINS>
   GSSManager mgr = GSSManager.getInstance();

   // start by creating a name object for the entity
   GSSName name = mgr.createName("userName", GSSName.NT_USER_NAME);

   // now acquire credentials for the entity
   GSSCredential cred = mgr.createCredential(name,
              GSSCredential.INDEFINITE_LIFETIME,
              (Oid[])null,
              GSSCredential.ACCEPT_ONLY);

   // display credential information - name, remaining lifetime,
   // and the mechanisms it has been acquired over
   print(cred.getName().toString());
   print(cred.getRemainingLifetime());

   Oid[] mechs = cred.getMechs();
   if (mechs != null) {
      for (int i = 0; i < mechs.length; i++)
          print(mechs[i].toString());
   }
   // release system resources held by the credential
   cred.dispose();
   <CODE ENDS>

7.4.  public interface GSSContext

   This interface encapsulates the GSS-API security context and provides
   the security services (wrap, unwrap, getMIC, and verifyMIC) that are
   available over the context.  Security contexts are established
   between peers using locally acquired credentials.  Multiple contexts
   may exist simultaneously between a pair of peers, using the same or



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   different set of credentials.  GSS-API functions in a manner
   independent of the underlying transport protocol and depends on its
   calling application to transport its tokens between peers.

   Before the context establishment phase is initiated, the context
   initiator may request specific characteristics desired of the
   established context.  These can be set using the set methods.  After
   the context is established, the caller can check the actual
   characteristic and services offered by the context using the query
   methods.

   The context establishment phase begins with the first call to the
   init method by the context initiator.  During this phase, the
   initSecContext and acceptSecContext methods will produce GSS-API
   authentication tokens, which the calling application needs to send to
   its peer.  If an error occurs at any point, an exception will get
   thrown and the code will start executing in a catch block where the
   exception may contain an output token that should be sent to the peer
   for debugging or informational purpose.  If not, the normal flow of
   code continues, and the application can make a call to the
   isEstablished() method.  If this method returns "false", it indicates
   that a token is needed from its peer in order to continue the context
   establishment phase.  A return value of "true" signals that the local
   end of the context is established.  This may still require that a
   token be sent to the peer, if one is produced by GSS-API.  During the
   context establishment phase, the isProtReady() method may be called
   to determine if the context can be used for the per-message
   operations.  This allows applications to use per-message operations
   on contexts that aren't fully established.

   After the context has been established or the isProtReady() method
   returns "true", the query routines can be invoked to determine the
   actual characteristics and services of the established context.  The
   application can also start using the per-message methods of wrap and
   getMIC to obtain cryptographic operations on application-supplied
   data.

   When the context is no longer needed, the application SHOULD call
   dispose to release any system resources the context may be using.

7.4.1.  Static Constants

   public static final int DEFAULT_LIFETIME

   A lifetime constant representing the default context lifetime.  The
   value of this constant is 0.





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   public static final int INDEFINITE_LIFETIME

   A lifetime constant representing indefinite context lifetime.  The
   value of this constant is the maximum integer value in Java --
   Integer.MAX_VALUE.

7.4.2.  initSecContext

   public byte[] initSecContext(byte[] inputBuf, int offset, int len)
                 throws GSSException

   Called by the context initiator to start the context creation
   process.  This method MAY return an output token that the application
   will need to send to the peer for processing by the accept call.  The
   application can call isEstablished() to determine if the context
   establishment phase is complete for this peer.  A return value of
   "false" from isEstablished() indicates that more tokens are expected
   to be supplied to the initSecContext() method.  Note that it is
   possible that the initSecContext() method will return a token for the
   peer and isEstablished() will return "true" also.  This indicates
   that the token needs to be sent to the peer, but the local end of the
   context is now fully established.

   Upon completion of the context establishment, the available context
   options may be queried through the get methods.

   A GSSException will be thrown if the call fails.  Users SHOULD call
   its getOutputToken() method to find out if there is a token that can
   be sent to the acceptor to communicate the reason for the error.

   Parameters:

   inputBuf            Token generated by the peer.  This parameter is
                       ignored on the first call.

   offset              The offset within the inputBuf where the token
                       begins.

   len                 The length of the token within the inputBuf
                       (starting at the offset).

7.4.3.  acceptSecContext

   public byte[] acceptSecContext(byte[] inTok, int offset, int len)
              throws GSSException

   Called by the context acceptor upon receiving a token from the peer.




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   This method MAY return an output token that the application will need
   to send to the peer for further processing by the init call.

   The "null" return value indicates that no token needs to be sent to
   the peer.  The application can call isEstablished() to determine if
   the context establishment phase is complete for this peer.  A return
   value of "false" from isEstablished() indicates that more tokens are
   expected to be supplied to this method.

   Note that it is possible that acceptSecContext() will return a token
   for the peer and isEstablished() will return "true" also.  This
   indicates that the token needs to be sent to the peer, but the local
   end of the context is now fully established.

   Upon completion of the context establishment, the available context
   options may be queried through the get methods.

   A GSSException will be thrown if the call fails.  Users SHOULD call
   its getOutputToken() method to find out if there is a token that can
   be sent to the initiator to communicate the reason for the error.

   Parameters:

   inTok               Token generated by the peer.

   offset              The offset within the inTok where the token
                       begins.

   len                 The length of the token within the inTok
                       (starting at the offset).

7.4.4.  isEstablished

   public boolean isEstablished()

   Used during context establishment to determine the state of the
   context.  Returns "true" if this is a fully established context on
   the caller's side and no more tokens are needed from the peer.
   Should be called after a call to initSecContext() or
   acceptSecContext() when no GSSException is thrown.

7.4.5.  dispose

   public void dispose() throws GSSException

   Releases any system resources and cryptographic information stored in
   the context object.  This will invalidate the context.




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7.4.6.  getWrapSizeLimit

   public int getWrapSizeLimit(int qop, boolean confReq,
              int maxTokenSize) throws GSSException

   Returns the maximum message size that, if presented to the wrap
   method with the same confReq and qop parameters, will result in an
   output token containing no more than the maxTokenSize bytes.

   This call is intended for use by applications that communicate over
   protocols that impose a maximum message size.  It enables the
   application to fragment messages prior to applying protection.

   GSS-API implementations are RECOMMENDED but not required to detect
   invalid QOP values when getWrapSizeLimit is called.  This routine
   guarantees only a maximum message size, not the availability of
   specific QOP values for message protection.

   Successful completion of this call does not guarantee that wrap will
   be able to protect a message of the computed length, since this
   ability may depend on the availability of system resources at the
   time that wrap is called.  However, if the implementation itself
   imposes an upper limit on the length of messages that may be
   processed by wrap, the implementation SHOULD NOT return a value that
   is greater than this length.

   Parameters:

   qop                 Indicates the level of protection wrap will be
                       asked to provide.

   confReq             Indicates if wrap will be asked to provide
                       privacy service.

   maxTokenSize        The desired maximum size of the token emitted by
                       wrap.

7.4.7.  wrap

   public byte[] wrap(byte[] inBuf, int offset, int len,
                      MessageProp msgProp) throws GSSException

   Applies per-message security services over the established security
   context.  The method will return a token with a cryptographic MIC and
   MAY optionally encrypt the specified inBuf.  The returned byte array
   will contain both the MIC and the message.





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   The MessageProp object is instantiated by the application and used to
   specify a QOP value that selects cryptographic algorithms and a
   privacy service to optionally encrypt the message.  The underlying
   mechanism that is used in the call may not be able to provide the
   privacy service.  It sets the actual privacy service that it does
   provide in this MessageProp object, which the caller SHOULD then
   query upon return.  If the mechanism is not able to provide the
   requested QOP, it throws a GSSException with the BAD_QOP code.

   Since some application-level protocols may wish to use tokens emitted
   by wrap to provide "secure framing", implementations SHOULD support
   the wrapping of zero-length messages.

   The application will be responsible for sending the token to the
   peer.

   Parameters:

   inBuf               Application data to be protected.

   offset              The offset within the inBuf where the data
                       begins.

   len                 The length of the data within the inBuf (starting
                       at the offset).

   msgProp             Instance of MessageProp that is used by the
                       application to set the desired QOP and privacy
                       state.  Set the desired QOP to 0 to request the
                       default QOP.  Upon return from this method, this
                       object will contain the actual privacy state that
                       was applied to the message by the underlying
                       mechanism.

7.4.8.  unwrap

   public byte[] unwrap(byte[] inBuf, int offset, int len,
                        MessageProp msgProp) throws GSSException

   Used by the peer application to process tokens generated with the
   wrap call.  The method will return the message supplied in the peer
   application to the wrap call, verifying the embedded MIC.

   The MessageProp object is instantiated by the application and is used
   by the underlying mechanism to return information to the caller such
   as the QOP, whether confidentiality was applied to the message, and
   other supplementary message state information.




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   Since some application-level protocols may wish to use tokens emitted
   by wrap to provide "secure framing", implementations SHOULD support
   the wrapping and unwrapping of zero-length messages.

   Parameters:

   inBuf               GSS-API wrap token received from peer.

   offset              The offset within the inBuf where the token
                       begins.

   len                 The length of the token within the inBuf
                       (starting at the offset).

   msgProp             Upon return from the method, this object will
                       contain the applied QOP, the privacy state of the
                       message, and supplementary information, described
                       in Section 5.12.3, stating whether the token was
                       a duplicate, old, out of sequence, or arriving
                       after a gap.

7.4.9.  getMIC

   public byte[] getMIC(byte[] inMsg, int offset, int len,
                        MessageProp msgProp) throws GSSException

   Returns a token containing a cryptographic MIC for the supplied
   message for transfer to the peer application.  Unlike wrap, which
   encapsulates the user message in the returned token, only the message
   MIC is returned in the output token.

   Note that privacy can only be applied through the wrap call.

   Since some application-level protocols may wish to use tokens emitted
   by getMIC to provide "secure framing", implementations SHOULD support
   derivation of MICs from zero-length messages.

   Parameters:

   inMsg               Message over which to generate MIC.

   offset              The offset within the inMsg where the token
                       begins.

   len                 The length of the token within the inMsg
                       (starting at the offset).





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   msgProp             Instance of MessageProp that is used by the
                       application to set the desired QOP.  Set the
                       desired QOP to 0 in msgProp to request the
                       default QOP.  Alternatively, pass in "null" for
                       msgProp to request default QOP.

7.4.10.  verifyMIC

   public void verifyMIC(byte[] inTok, int tokOffset, int tokLen,
                         byte[] inMsg, int msgOffset, int msgLen,
                         MessageProp msgProp) throws GSSException

   Verifies the cryptographic MIC, contained in the token parameter,
   over the supplied message.

   The MessageProp object is instantiated by the application and is used
   by the underlying mechanism to return information to the caller such
   as the QOP indicating the strength of protection that was applied to
   the message and other supplementary message state information.

   Since some application-level protocols may wish to use tokens emitted
   by getMIC to provide "secure framing", implementations SHOULD support
   the calculation and verification of MICs over zero-length messages.

   Parameters:

   inTok               Token generated by peer's getMIC method.

   tokOffset           The offset within the inTok where the token
                       begins.

   tokLen              The length of the token within the inTok
                       (starting at the offset).

   inMsg               Application message over which to verify the
                       cryptographic MIC.

   msgOffset           The offset within the inMsg where the message
                       begins.

   msgLen              The length of the message within the inMsg
                       (starting at the offset).









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   msgProp             Upon return from the method, this object will
                       contain the applied QOP and supplementary
                       information, described in Section 5.12.3, stating
                       whether the token was a duplicate, old, out of
                       sequence, or arriving after a gap.  The
                       confidentiality state will be set to "false".

7.4.11.  export

   public byte[] export() throws GSSException

   Provided to support the sharing of work between multiple processes.
   This routine will typically be used by the context acceptor, in an
   application where a single process receives incoming connection
   requests and accepts security contexts over them, then passes the
   established context to one or more other processes for message
   exchange.

   This method deactivates the security context and creates an inter-
   process token that, when passed to the byte array constructor of the
   GSSContext interface in another process, will re-activate the context
   in the second process.  Only a single instantiation of a given
   context may be active at any one time; a subsequent attempt by a
   context exporter to access the exported security context will fail.

   The implementation MAY constrain the set of processes by which the
   inter-process token may be imported, either as a function of local
   security policy or as a result of implementation decisions.  For
   example, some implementations may constrain contexts to be passed
   only between processes that run under the same account, or which are
   part of the same process group.

   The inter-process token MAY contain security-sensitive information
   (for example, cryptographic keys).  While mechanisms are encouraged
   either to avoid placing such sensitive information within inter-
   process tokens or to encrypt the token before returning it to the
   application, in a typical GSS-API implementation, this may not be
   possible.  Thus, the application MUST take care to protect the inter-
   process token and ensure that any process to which the token is
   transferred is trustworthy.

7.4.12.  requestMutualAuth

   public void requestMutualAuth(boolean state) throws GSSException

   Sets the request state of the mutual authentication flag for the
   context.  This method is only valid before the context creation
   process begins and only for the initiator.



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   Parameters:

   state               Boolean representing if mutual authentication
                       should be requested during context establishment.

7.4.13.  requestReplayDet

   public void requestReplayDet(boolean state) throws GSSException

   Sets the request state of the replay detection service for the
   context.  This method is only valid before the context creation
   process begins and only for the initiator.

   Parameters:

   state               Boolean representing if replay detection is
                       desired over the established context.

7.4.14.  requestSequenceDet

   public void requestSequenceDet(boolean state) throws GSSException

   Sets the request state for the sequence-checking service of the
   context.  This method is only valid before the context creation
   process begins and only for the initiator.

   Parameters:

   state               Boolean representing if sequence detection is
                       desired over the established context.

7.4.15.  requestCredDeleg

   public void requestCredDeleg(boolean state) throws GSSException

   Sets the request state for the credential delegation flag for the
   context.  This method is only valid before the context creation
   process begins and only for the initiator.

   Parameters:

   state               Boolean representing if credential delegation is
                       desired.








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7.4.16.  requestAnonymity

   public void requestAnonymity(boolean state) throws GSSException

   Requests anonymous support over the context.  This method is only
   valid before the context creation process begins and only for the
   initiator.

   Parameters:

   state               Boolean representing if anonymity support is
                       requested.

7.4.17.  requestConf

   public void requestConf(boolean state) throws GSSException

   Requests that confidentiality service be available over the context.
   This method is only valid before the context creation process begins
   and only for the initiator.

   Parameters:

   state               Boolean indicating if confidentiality services
                       are to be requested for the context.

7.4.18.  requestInteg

   public void requestInteg(boolean state) throws GSSException

   Requests that integrity services be available over the context.  This
   method is only valid before the context creation process begins and
   only for the initiator.

   Parameters:

   state               Boolean indicating if integrity services are to
                       be requested for the context.

7.4.19.  requestLifetime

   public void requestLifetime(int lifetime) throws GSSException

   Sets the desired lifetime for the context in seconds.  This method is
   only valid before the context creation process begins and only for
   the initiator.  Use GSSContext.INDEFINITE_LIFETIME and
   GSSContext.DEFAULT_LIFETIME to request indefinite or default context
   lifetime.



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   Parameters:

   lifetime            The desired context lifetime in seconds.

7.4.20.  setChannelBinding

   public void setChannelBinding(ChannelBinding cb) throws GSSException

   Sets the channel bindings to be used during context establishment.
   This method is only valid before the context creation process begins.

   Parameters:

   cb                  Channel bindings to be used.

7.4.21.  getCredDelegState

   public boolean getCredDelegState()

   Returns the state of the delegated credentials for the context.  When
   issued before context establishment is completed or when the
   isProtReady method returns "false", it returns the desired state;
   otherwise, it will indicate the actual state over the established
   context.

7.4.22.  getMutualAuthState

   public boolean getMutualAuthState()

   Returns the state of the mutual authentication option for the
   context.  When issued before context establishment completes or when
   the isProtReady method returns "false", it returns the desired state;
   otherwise, it will indicate the actual state over the established
   context.

7.4.23.  getReplayDetState

   public boolean getReplayDetState()

   Returns the state of the replay detection option for the context.
   When issued before context establishment completes or when the
   isProtReady method returns "false", it returns the desired state;
   otherwise, it will indicate the actual state over the established
   context.







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7.4.24.  getSequenceDetState

   public boolean getSequenceDetState()

   Returns the state of the sequence detection option for the context.
   When issued before context establishment completes or when the
   isProtReady method returns "false", it returns the desired state;
   otherwise, it will indicate the actual state over the established
   context.

7.4.25.  getAnonymityState

   public boolean getAnonymityState()

   Returns "true" if this is an anonymous context.  When issued before
   context establishment completes or when the isProtReady method
   returns "false", it returns the desired state; otherwise, it will
   indicate the actual state over the established context.

7.4.26.  isTransferable

   public boolean isTransferable() throws GSSException

   Returns "true" if the context is transferable to other processes
   through the use of the export method.  This call is only valid on
   fully established contexts.

7.4.27.  isProtReady

   public boolean isProtReady()

   Returns "true" if the per-message operations can be applied over the
   context.  Some mechanisms may allow the usage of per-message
   operations before the context is fully established.  This will also
   indicate that the get methods will return actual context state
   characteristics instead of the desired ones.

7.4.28.  getConfState

   public boolean getConfState()

   Returns the confidentiality service state over the context.  When
   issued before context establishment completes or when the isProtReady
   method returns "false", it returns the desired state; otherwise, it
   will indicate the actual state over the established context.






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7.4.29.  getIntegState

   public boolean getIntegState()

   Returns the integrity service state over the context.  When issued
   before context establishment completes or when the isProtReady method
   returns "false", it returns the desired state; otherwise, it will
   indicate the actual state over the established context.

7.4.30.  getLifetime

   public int getLifetime()

   Returns the context lifetime in seconds.  When issued before context
   establishment completes or when the isProtReady method returns
   "false", it returns the desired lifetime; otherwise, it will indicate
   the remaining lifetime for the context.

7.4.31.  getSrcName

   public GSSName getSrcName() throws GSSException

   Returns the name of the context initiator.  This call is valid only
   after the context is fully established or the isProtReady method
   returns "true".  It is guaranteed to return an MN.

7.4.32.  getTargName

   public GSSName getTargName() throws GSSException

   Returns the name of the context target (acceptor).  This call is
   valid only after the context is fully established or the isProtReady
   method returns "true".  It is guaranteed to return an MN.

7.4.33.  getMech

   public Oid getMech() throws GSSException

   Returns the mechanism OID for this context.  This method MAY be
   called before the context is fully established, but the mechanism
   returned MAY change on successive calls in a negotiated mechanism
   case.









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7.4.34.  getDelegCred

   public GSSCredential getDelegCred() throws GSSException

   Returns the delegated credential object on the acceptor's side.  To
   check for availability of delegated credentials, call
   getDelegCredState.  This call is only valid on fully established
   contexts.

7.4.35.  isInitiator

   public boolean isInitiator() throws GSSException

   Returns "true" if this is the initiator of the context.  This call is
   only valid after the context creation process has started.

7.4.36.  Example Code

   The example code presented below demonstrates the usage of the
   GSSContext interface for the initiating peer.  Different operations
   on the GSSContext object are presented, including: object
   instantiation, setting of desired flags, context establishment, query
   of actual context flags, per-message operations on application data,
   and finally context deletion.

   <CODE BEGINS>
   GSSManager mgr = GSSManager.getInstance();

   // start by creating the name for a service entity
   GSSName targetName = mgr.createName("service@host",
                        GSSName.NT_HOSTBASED_SERVICE);
   // create a context using default credentials for the above entity
   // and the implementation-specific default mechanism
   GSSContext context = mgr.createContext(targetName,
                   null,   /* default mechanism */
                   null,   /* default credentials */
                   GSSContext.INDEFINITE_LIFETIME);

   // set desired context options - all others are "false" by default
   context.requestConf(true);
   context.requestMutualAuth(true);
   context.requestReplayDet(true);
   context.requestSequenceDet(true);

   // establish a context between peers - using byte arrays
   byte[] inTok = new byte[0];





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   try {
       do {
           byte[] outTok = context.initSecContext(inTok, 0,
                                                 inTok.length);

           // send the token if present
           if (outTok != null)
               sendToken(outTok);

           // check if we should expect more tokens
           if (context.isEstablished())
               break;

           // another token expected from peer
           inTok = readToken();

       } while (true);

   } catch (GSSException e) {
       print("GSSAPI error: " + e.getMessage());

       // If the exception contains an output token,
       // it should be sent to the acceptor.
       byte[] outTok = e.getOutputToken();
       if (outTok != null) {
           sendToken(outTok);
       }

       return;
   }

   // display context information
   print("Remaining lifetime in seconds = " + context.getLifetime());
   print("Context mechanism = " + context.getMech().toString());
   print("Initiator = " + context.getSrcName().toString());
   print("Acceptor = " + context.getTargName().toString());

   if (context.getConfState())
       print("Confidentiality security service available");

   if (context.getIntegState())
       print("Integrity security service available");

   // perform wrap on an application-supplied message, appMsg,
   // using QOP = 0, and requesting privacy service
   byte[] appMsg ...

   MessageProp mProp = new MessageProp(0, true);



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   byte[] tok = context.wrap(appMsg, 0, appMsg.length, mProp);

   if (mProp.getPrivacy())
       print("Message protected with privacy.");

   sendToken(tok);

   // release the local end of the context
   context.dispose();
   <CODE ENDS>

7.5.  public class MessageProp

   This is a utility class used within the per-message GSSContext
   methods to convey per-message properties.

   When used with the GSSContext interface's wrap and getMIC methods, an
   instance of this class is used to indicate the desired QOP and to
   request if confidentiality services are to be applied to caller-
   supplied data (wrap only).  To request default QOP, the value of 0
   should be used for QOP.  A QOP is an integer value defined by an
   mechanism.

   When used with the unwrap and verifyMIC methods of the GSSContext
   interface, an instance of this class will be used to indicate the
   applied QOP and confidentiality services over the supplied message.
   In the case of verifyMIC, the confidentiality state will always be
   "false".  Upon return from these methods, this object will also
   contain any supplementary status values applicable to the processed
   token.  The supplementary status values can indicate old tokens, out
   of sequence tokens, gap tokens, or duplicate tokens.

7.5.1.  Constructors

   public MessageProp(boolean privState)

   Constructor that sets QOP to 0 indicating that the default QOP is
   requested.

   Parameters:

   privState           The desired privacy state. "true" for privacy and
                       "false" for integrity only.

   public MessageProp(int qop, boolean privState)

   Constructor that sets the values for the QOP and privacy state.




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   Parameters:

   qop                 The desired QOP.  Use 0 to request a default QOP.

   privState           The desired privacy state. "true" for privacy and
                       "false" for integrity only.

7.5.2.  getQOP

   public int getQOP()

   Retrieves the QOP value.

7.5.3.  getPrivacy

   public boolean getPrivacy()

   Retrieves the privacy state.

7.5.4.  getMinorStatus

   public int getMinorStatus()

   Retrieves the minor status that the underlying mechanism might have
   set.

7.5.5.  getMinorString

   public String getMinorString()

   Returns a string explaining the mechanism-specific error code. "null"
   will be returned when no mechanism error code has been set.

7.5.6.  setQOP

   public void setQOP(int qopVal)

   Sets the QOP value.

   Parameters:

   qopVal              The QOP value to be set.  Use 0 to request a
                       default QOP value.








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7.5.7.  setPrivacy

   public void setPrivacy(boolean privState)

   Sets the privacy state.

   Parameters:

   privState           The privacy state to set.

7.5.8.  isDuplicateToken

   public boolean isDuplicateToken()

   Returns "true" if this is a duplicate of an earlier token.

7.5.9.  isOldToken

   public boolean isOldToken()

   Returns "true" if the token's validity period has expired.

7.5.10.  isUnseqToken

   public boolean isUnseqToken()

   Returns "true" if a later token has already been processed.

7.5.11.  isGapToken

   public boolean isGapToken()

   Returns "true" if an expected per-message token was not received.

7.5.12.  setSupplementaryStates

   public void setSupplementaryStates(boolean duplicate,
                  boolean old, boolean unseq, boolean gap,
                  int minorStatus, String minorString)

   This method sets the state for the supplementary information flags
   and the minor status in MessageProp.  It is not used by the
   application but by the GSS implementation to return this information
   to the caller of a per-message context method.







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   Parameters:

   duplicate           "true" if the token was a duplicate of an earlier
                       token; otherwise, "false".

   old                 "true" if the token's validity period has
                       expired; otherwise, "false".

   unseq               "true" if a later token has already been
                       processed; otherwise, "false".

   gap                 "true" if one or more predecessor tokens have not
                       yet been successfully processed; otherwise,
                       "false".

   minorStatus         The integer minor status code that the underlying
                       mechanism wants to set.

   minorString         The textual representation of the minorStatus
                       value.

7.6.  public class ChannelBinding

   The GSS-API accommodates the concept of caller-provided channel-
   binding information.  Channel bindings are used to strengthen the
   quality with which peer entity authentication is provided during
   context establishment.  They enable the GSS-API callers to bind the
   establishment of the security context to relevant characteristics
   like addresses or to application-specific data.

   The caller initiating the security context MUST determine the
   appropriate channel-binding values to set in the GSSContext object.
   The acceptor MUST provide an identical binding in order to validate
   that received tokens possess correct channel-related characteristics.

   Use of channel bindings is OPTIONAL in GSS-API.  Since channel-
   binding information may be transmitted in context establishment
   tokens, applications SHOULD therefore not use confidential data as
   channel-binding components.

7.6.1.  Constructors

   public ChannelBinding(InetAddress initAddr, InetAddress acceptAddr,
                         byte[] appData)

   Create a ChannelBinding object with user-supplied address information
   and data. "null" values can be used for any fields that the
   application does not want to specify.



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   Parameters:

   initAddr            The address of the context initiator.  The "null"
                       value can be supplied to indicate that the
                       application does not want to set this value.

   acceptAddr          The address of the context acceptor.  The "null"
                       value can be supplied to indicate that the
                       application does not want to set this value.

   appData             Application-supplied data to be used as part of
                       the channel bindings.  The "null" value can be
                       supplied to indicate that the application does
                       not want to set this value.

   public ChannelBinding(byte[] appData)

   Creates a ChannelBinding object without any addressing information.

   Parameters:

   appData             Application-supplied data to be used as part of
                       the channel bindings.

7.6.2.  getInitiatorAddress

   public InetAddress getInitiatorAddress()

   Returns the initiator's address for this channel binding. "null" is
   returned if the address has not been set.

7.6.3.  getAcceptorAddress

   public InetAddress getAcceptorAddress()

   Returns the acceptor's address for this channel binding. "null" is
   returned if the address has not been set.

7.6.4.  getApplicationData

   public byte[] getApplicationData()

   Returns application data being used as part of the ChannelBinding.
   "null" is returned if no application data has been specified for the
   channel binding.






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7.6.5.  equals

   public boolean equals(Object obj)

   Returns "true" if two channel bindings match.  (Note that the Java
   language specification requires that two objects that are equal
   according to the equals(Object) method MUST return the same integer
   result when the hashCode() method is called on them.)

   Parameters:

   obj                 Another channel binding with which to compare.

7.7.  public class Oid

   This class represents Universal OIDs and their associated operations.

   OIDs are hierarchically globally interpretable identifiers used
   within the GSS-API framework to identify mechanisms and name formats.

   The structure and encoding of OIDs is defined in ISOIEC-8824
   [ISOIEC-8824] and ISOIEC-8825 [ISOIEC-8825].  For example, the OID
   representation of the Kerberos v5 mechanism is
   "1.2.840.113554.1.2.2".

   The GSSName name class contains public static Oid objects
   representing the standard name types defined in GSS-API.

7.7.1.  Constructors

   public Oid(String strOid) throws GSSException

   Creates an Oid object from a string representation of its integer
   components (e.g., "1.2.840.113554.1.2.2").

   Parameters:

   strOid              The string representation for the OID.

   public Oid(InputStream derOid) throws GSSException

   Creates an Oid object from its DER encoding.  This refers to the full
   encoding including tag and length.  The structure and encoding of
   OIDs is defined in ISOIEC-8824 [ISOIEC-8824] and ISOIEC-8825
   [ISOIEC-8825].  This method is identical in functionality to its byte
   array counterpart.





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   Parameters:

   derOid              Stream containing the DER-encoded OID.

   public Oid(byte[] derOid) throws GSSException

   Creates an Oid object from its DER encoding.  This refers to the full
   encoding including tag and length.  The structure and encoding of
   OIDs is defined in ISOIEC-8824 [ISOIEC-8824] and ISOIEC-8825
   [ISOIEC-8825].  This method is identical in functionality to its byte
   array counterpart.

   Parameters:

   derOid              Byte array storing a DER-encoded OID.

7.7.2.  toString

   public String toString()

   Returns a string representation of the OID's integer components in
   dot-separated notation (e.g., "1.2.840.113554.1.2.2").

7.7.3.  equals

   public boolean equals(Object Obj)

   Returns "true" if the two Oid objects represent the same OID value.
   (Note that the Java language specification [JLS] requires that two
   objects that are equal according to the equals(Object) method MUST
   return the same integer result when the hashCode() method is called
   on them.)

   Parameters:

   obj                 Another Oid object with which to compare.

7.7.4.  getDER

   public byte[] getDER()

   Returns the full ASN.1 DER encoding for this Oid object, which
   includes the tag and length.








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7.7.5.  containedIn

   public boolean containedIn(Oid[] oids)

   A utility method to test if an Oid object is contained within the
   supplied Oid object array.

   Parameters:

   oids                An array of OIDs to search.

7.8.  public class GSSException extends Exception

   This exception is thrown whenever a fatal GSS-API error occurs
   including mechanism-specific errors.  It MAY contain both, the major
   and minor, GSS-API status codes.  The mechanism implementors are
   responsible for setting appropriate minor status codes when throwing
   this exception.  Aside from delivering the numeric error code(s) to
   the caller, this class performs the mapping from their numeric values
   to textual representations.  This exception MAY also include an
   output token that SHOULD be sent to the peer.  For example, when an
   initSecContext call fails due to a fatal error, the mechanism MAY
   define an error token that SHOULD be sent to the peer for debugging
   or informational purposes.  All Java GSS-API methods are declared
   throwing this exception.

   All implementations are encouraged to use the Java
   internationalization techniques to provide local translations of the
   message strings.

7.8.1.  Static Constants

   All valid major GSS-API error code values are declared as constants
   in this class.

   public static final int BAD_BINDINGS

   Channel-bindings mismatch error.  The value of this constant is 1.

   public static final int BAD_MECH

   Unsupported mechanism requested error.  The value of this constant is
   2.

   public static final int BAD_NAME

   Invalid name provided error.  The value of this constant is 3.




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   public static final int BAD_NAMETYPE

   Name of unsupported type provided error.  The value of this constant
   is 4.

   public static final int BAD_STATUS

   Invalid status code error - this is the default status value.  The
   value of this constant is 5.

   public static final int BAD_MIC

   Token had invalid integrity check error.  The value of this constant
   is 6.

   public static final int CONTEXT_EXPIRED

   Specified security context expired error.  The value of this constant
   is 7.

   public static final int CREDENTIALS_EXPIRED

   Expired credentials detected error.  The value of this constant is 8.

   public static final int DEFECTIVE_CREDENTIAL

   Defective credential error.  The value of this constant is 9.

   public static final int DEFECTIVE_TOKEN

   Defective token error.  The value of this constant is 10.

   public static final int FAILURE

   General failure, unspecified at GSS-API level.  The value of this
   constant is 11.

   public static final int NO_CONTEXT

   Invalid security context error.  The value of this constant is 12.

   public static final int NO_CRED

   Invalid credentials error.  The value of this constant is 13.

   public static final int BAD_QOP

   Unsupported QOP value error.  The value of this constant is 14.



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   public static final int UNAUTHORIZED

   Operation unauthorized error.  The value of this constant is 15.

   public static final int UNAVAILABLE

   Operation unavailable error.  The value of this constant is 16.

   public static final int DUPLICATE_ELEMENT

   Duplicate credential element requested error.  The value of this
   constant is 17.

   public static final int NAME_NOT_MN

   Name contains multi-mechanism elements error.  The value of this
   constant is 18.

   public static final int DUPLICATE_TOKEN

   The token was a duplicate of an earlier token.  This is contained in
   an exception only when detected during context establishment, in
   which case it is considered a fatal error.  (Non-fatal supplementary
   codes are indicated via the MessageProp object.)  The value of this
   constant is 19.

   public static final int OLD_TOKEN

   The token's validity period has expired.  This is contained in an
   exception only when detected during context establishment, in which
   case it is considered a fatal error.  (Non-fatal supplementary codes
   are indicated via the MessageProp object.)  The value of this
   constant is 20.

   public static final int UNSEQ_TOKEN

   A later token has already been processed.  This is contained in an
   exception only when detected during context establishment, in which
   case it is considered a fatal error.  (Non-fatal supplementary codes
   are indicated via the MessageProp object.)  The value of this
   constant is 21.










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   public static final int GAP_TOKEN

   An expected per-message token was not received.  This is contained in
   an exception only when detected during context establishment, in
   which case it is considered a fatal error.  (Non-fatal supplementary
   codes are indicated via the MessageProp object.)  The value of this
   constant is 22.

7.8.2.  Constructors

   public GSSException(int majorCode)

   Creates a GSSException object with a specified major code.

   Calling this constructor is equivalent to calling
   GSSException(majorCode, null, 0, null, null).

   public GSSException(int majorCode, int minorCode, String minorString)

   Creates a GSSException object with the specified major code, minor
   code, and minor code textual explanation.  This constructor is to be
   used when the exception is originating from the security mechanism.
   It allows to specify the GSS code and the mechanism code.

   Calling this constructor is equivalent to calling
   GSSException(majorCode, null, minorCode, minorString, null).

   public GSSException(int majorCode, String majorString,
                       int minorCode, String minorString,
                       byte[] outputToken)

   Creates a GSSException object with the specified major code, major
   code textual explanation, minor code, minor code textual explanation,
   and an output token.  This is a general-purpose constructor that can
   be used to create any type of GSSException.

   Parameters:

   majorCode           The GSS error code causing this exception to be
                       thrown.

   majorString         The textual explanation of the GSS error code.
                       If null is provided, a default explanation that
                       matches the majorCode will be set.

   minorCode           The mechanism error code causing this exception
                       to be thrown.  Can be 0 if no mechanism error
                       code is available.



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   minorString         The textual explanation of the mechanism error
                       code.  Can be null if no textual explanation is
                       available.

   outputToken         The output token that SHOULD be sent to the peer.
                       Can be null if no such token is available.  It
                       MUST NOT be an empty array.  When provided, the
                       array will be cloned to protect against
                       subsequent modifications.

7.8.3.  getMajor

   public int getMajor()

   Returns the major code representing the GSS error code that caused
   this exception to be thrown.

7.8.4.  getMinor

   public int getMinor()

   Returns the mechanism error code that caused this exception.  The
   minor code is set by the underlying mechanism.  The value of 0
   indicates that the mechanism error code is not set.

7.8.5.  getMajorString

   public String getMajorString()

   Returns a string explaining the GSS major error code causing this
   exception to be thrown.

7.8.6.  getMinorString

   public String getMinorString()

   Returns a string explaining the mechanism-specific error code. "null"
   will be returned when no string explaining the mechanism error code
   has been set.












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7.8.7.  getOutputToken

   public byte[] getOutputToken

   Returns the output token in a new byte array.

   If the method (for example, GSSContext#initSecContext) that throws
   this GSSException needs to generate an output token that SHOULD be
   sent to the peer, that token will be stored in this GSSException and
   can be retrieved with this method.

   The return value MUST be null if no such token is generated.  It MUST
   NOT be an empty byte array.

7.8.8.  setMinor

   public void setMinor(int minorCode, String message)

   Used internally by the GSS-API implementation and the underlying
   mechanisms to set the minor code and its textual representation.

   Parameters:

   minorCode           The mechanism-specific error code.

   message             A textual explanation of the mechanism error
                       code.

7.8.9.  toString

   public String toString()

   Returns a textual representation of both the major and minor status
   codes.

7.8.10.  getMessage

   public String getMessage()

   Returns a detailed message of this exception.  Overrides
   Throwable.getMessage.  It is customary in Java to use this method to
   obtain exception information.









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8.  Sample Applications

8.1.  Simple GSS Context Initiator

   <CODE BEGINS>
   import org.ietf.jgss.*;

   /**
    * This is a partial sketch for a simple client program that acts
    * as a GSS context initiator.  It illustrates how to use the Java
    * bindings for the GSS-API specified in RFC 8353.
    *
    *
    * This code sketch assumes the existence of a GSS-API
    * implementation that supports the mechanism that it will need
    * and is present as a library package (org.ietf.jgss) either as
    * part of the standard JRE or in the CLASSPATH the application
    * specifies.
    */

    public class SimpleClient {

        private String serviceName; // name of peer (i.e., server)
        private GSSCredential clientCred = null;
        private GSSContext context = null;
        private Oid mech; // underlying mechanism to use

        private GSSManager mgr = GSSManager.getInstance();

        ...
        ...

        private void clientActions() {
           initializeGSS();
           establishContext();
           doCommunication();
        }

       /**
        * Acquire credentials for the client.
        */
       private void initializeGSS() {

           try {

               clientCred = mgr.createCredential(null /*default princ*/,
                   GSSCredential.INDEFINITE_LIFETIME /* max lifetime */,
                   mech /* mechanism to use */,



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                   GSSCredential.INITIATE_ONLY /* init context */);

               print("GSSCredential created for " +
                     clientCred.getName().toString());
               print("Credential lifetime (sec)=" +
                     clientCred.getRemainingLifetime());
           } catch (GSSException e) {
               print("GSS-API error in credential acquisition: "
                     + e.getMessage());
               ...
               ...
           }
           ...
           ...
       }

       /**
        * Does the security context establishment with the
        * server.
        */
       private void establishContext() {

           byte[] inToken = new byte[0];
           byte[] outToken = null;

           try {

               GSSName peer = mgr.createName(serviceName,
                                     GSSName.NT_HOSTBASED_SERVICE);
               context = mgr.createContext(peer, mech, clientCred,
                      GSSContext.INDEFINITE_LIFETIME/*lifetime*/);

               // Will need to support confidentiality
               context.requestConf(true);

               while (!context.isEstablished()) {

                   outToken = context.initSecContext(inToken, 0,
                                                   inToken.length);

                   if (outToken != null)
                       writeGSSToken(outToken);

                   if (!context.isEstablished())
                       inToken = readGSSToken();
               }

               peer = context.getTargName();



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               print("Security context established with " + peer +
                     " using underlying mechanism " + mech.toString());
           } catch (GSSException e) {
                print("GSS-API error during context establishment: "
                      + e.getMessage());

                // If the exception contains an output token,
                // it should be sent to the acceptor.
                byte[] outTok = e.getOutputToken();
                if (outTok != null) {
                    writeGSSToken(outTok);
                }
                ...
                ...
           }
           ...
           ...
       }

       /**
        * Sends some data to the server and reads back the
        * response.
        */
       private void doCommunication()  {
           byte[] inToken = null;
           byte[] outToken = null;
           byte[] buffer;

           // Container for multiple input-output arguments to and
           // from the per-message routines (e.g., wrap/unwrap).
           MessageProp messgInfo = new MessageProp(true);

           try {

               /*
                * Now send some bytes to the server to be
                * processed.  They will be integrity protected
                * but not encrypted for privacy.
                */

               buffer = readFromFile();

               // Set privacy to "false" and use the default QOP
               messgInfo.setPrivacy(false);

               outToken = context.wrap(buffer, 0, buffer.length,
                                       messgInfo);




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               writeGSSToken(outToken);

               /*
                * Now read the response from the server.
                */

               inToken = readGSSToken();
               buffer = context.unwrap(inToken, 0,
                             inToken.length, messgInfo);
               // All ok if no exception was thrown!

               GSSName peer = context.getTargName();

               print("Message from "  + peer.toString()
                     + " arrived.");
               print("Was it encrypted? "  +
                     messgInfo.getPrivacy());
               print("Duplicate Token? "   +
                     messgInfo.isDuplicateToken());
               print("Old Token? "         +
                     messgInfo.isOldToken());
               print("Unsequenced Token? " +
                     messgInfo.isUnseqToken());
               print("Gap Token? "         +
                     messgInfo.isGapToken());
               ...
               ...
           } catch (GSSException e) {
               print("GSS-API error in per-message calls: "
                     + e.getMessage());
               ...
               ...
           }
           ...
           ...
       } // end of doCommunication method

       ...
       ...

   } // end of class SimpleClient
   <CODE ENDS>









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8.2.  Simple GSS Context Acceptor

   <CODE BEGINS>
   import org.ietf.jgss.*;

   /**
    * This is a partial sketch for a simple server program that acts
    * as a GSS context acceptor.  It illustrates how to use the Java
    * bindings for the GSS-API specified in
    * Generic Security Service API Version 2 : Java Bindings.
    *
    * This code sketch assumes the existence of a GSS-API
    * implementation that supports the mechanisms that it will need
    * and is present as a library package (org.ietf.jgss) either as
    * part of the standard JRE or in the CLASSPATH the application
    * specifies.
    */

   import org.ietf.jgss.*;

   public class SimpleServer {

       private String serviceName;
       private GSSName name;
       private GSSCredential cred;

       private GSSManager mgr;

       ...
       ...

       /**
        * Wait for client connections, establish security contexts,
        * and provide service.
        */
       private void loop() throws Exception {
           ...
           ...
           mgr = GSSManager.getInstance();

           name = mgr.createName(serviceName,
                     GSSName.NT_HOSTBASED_SERVICE);

           cred = mgr.createCredential(name,
                     GSSCredential.INDEFINITE_LIFETIME,
                     (Oid[])null,
                     GSSCredential.ACCEPT_ONLY);




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           // Loop infinitely
           while (true) {
               Socket s = serverSock.accept();

               // Start a new thread to serve this connection
               Thread serverThread = new ServerThread(s);
               serverThread.start();
           }
       }

       /**
        * Inner class ServerThread whose run() method provides the
        * secure service to a connection.
        */

       private class ServerThread extends Thread {

           ...
           ...

           /**
            * Deals with the connection from one client.  It also
            * handles all GSSException's thrown while talking to
            * this client.
            */
           public void run() {

               byte[] inToken = null;
               byte[] outToken = null;
               byte[] buffer;


               // Container for multiple input-output arguments to
               // and from the per-message routines
               // (i.e., wrap/unwrap).
               MessageProp supplInfo = new MessageProp(true);

               try {
                   // Now do the context establishment loop
                   GSSContext context = mgr.createContext(cred);

                   while (!context.isEstablished()) {

                       inToken = readGSSToken();
                       outToken = context.acceptSecContext(inToken,
                                                0, inToken.length);
                       if (outToken != null)
                           writeGSSToken(outToken);



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                   }

                   // SimpleServer wants confidentiality to be
                   // available.  Check for it.
                   if (!context.getConfState()){
                       ...
                       ...
                   }

                   GSSName peer = context.getSrcName();
                   Oid mech = context.getMech();
                   print("Security context established with " +
                          peer.toString() +
                         " using underlying mechanism " +
                         mech.toString());

                   // Now read the bytes sent by the client to be
                   // processed.
                   inToken = readGSSToken();

                   // Unwrap the message
                   buffer = context.unwrap(inToken, 0,
                               inToken.length, supplInfo);
                   // All ok if no exception was thrown!

                   // Print other supplementary per-message status
                   // information.

                   print("Message from " +
                           peer.toString() + " arrived.");
                   print("Was it encrypted? " +
                           supplInfo.getPrivacy());
                   print("Duplicate Token? " +
                           supplInfo.isDuplicateToken());
                   print("Old Token? "  + supplInfo.isOldToken());
                   print("Unsequenced Token? " +
                           supplInfo.isUnseqToken());
                   print("Gap Token? "  + supplInfo.isGapToken());

                   /*
                    * Now process the bytes and send back an
                    * encrypted response.
                    */

                   buffer = serverProcess(buffer);






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                   // Encipher it and send it across

                   supplInfo.setPrivacy(true); // privacy requested
                   supplInfo.setQOP(0); // default QOP
                   outToken = context.wrap(buffer, 0, buffer.length,
                                              supplInfo);
                   writeGSSToken(outToken);

               } catch (GSSException e) {
                   print("GSS-API Error: " + e.getMessage());
                   // Alternatively, could call e.getMajorMessage()
                   // and e.getMinorMessage()

                   // If the exception contains an output token,
                   // it should be sent to the initiator.
                   byte[] outTok = e.getOutputToken();
                   if (outTok != null) {
                       writeGSSToken(outTok);
                   }
                   print("Abandoning security context.");
                   ...
                   ...
               }
               ...
               ...
           } // end of run method in ServerThread

       } // end of inner class ServerThread

       ...
       ...

   } // end of class SimpleServer
   <CODE ENDS>

9.  Security Considerations

   The Java language security model allows platform providers to have
   policy-based fine-grained access control over any resource that an
   application wants.  When using a Java security manager (such as, but
   not limited to, the case of applets running in browsers), the
   application code is in a sandbox by default.

   Administrators of the platform JRE determine what permissions, if
   any, are to be given to source from different codebases.  Thus, the
   administrator has to be aware of any special requirements that the
   GSS provider might have for system resources.  For instance, a
   Kerberos provider might wish to make a network connection to the Key



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   Distribution Center (KDC) to obtain initial credentials.  This would
   not be allowed under the sandbox unless the administrator had granted
   permissions for this.  Also, note that this granting and checking of
   permissions happens transparently to the application and is outside
   the scope of this document.

   The Java language allows administrators to pre-configure a list of
   security service providers in the <JRE>/lib/security/java.security
   file.  At runtime, the system approaches these providers in order of
   preference when looking for security-related services.  Applications
   have a means to modify this list through methods in the "Security"
   class in the "java.security" package.  However, since these
   modifications would be visible in the entire Java Virtual Machine
   (JVM) and thus affect all code executing in it, this operation is not
   available in the sandbox and requires special permissions to perform.
   Thus, when a GSS application has special needs that are met by a
   particular security provider, it has two choices:

   1) Install the provider on a JVM-wide basis using the
      java.security.Security class and then depend on the system to find
      the right provider automatically when the need arises.  (This
      would require the application to be granted a "insertProvider
      SecurityPermission".)

   2) Pass an instance of the provider to the local instance of
      GSSManager so that only factory calls going through that
      GSSManager use the desired provider.  (This would not require any
      permissions.)

10.  IANA Considerations

   This document has no IANA actions.

11.  Changes since RFC 5653

   This document has following changes:

   1) New error token embedded in GSSException

      There is a design flaw in the initSecContext and acceptSecContext
      methods of the GSSContext class defined in "Generic Security
      Service API Version 2: Java Bindings Update" [RFC5653].

      The methods could either return a token (possibly null if no more
      tokens are needed) when the call succeeds or throw a GSSException
      if there is a failure, but NOT both.  On the other hand, the
      C-bindings of GSS-API [RFC2744] can return both; that is to say, a




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      call to the GSS_Init_sec_context() function can return a major
      status code, and at the same time, fill in the output_token
      argument if there is one.

      Without the ability to emit an error token when there is a
      failure, a Java application has no mechanism to tell the other
      side what the error is.  For example, a "reject" NegTokenResp
      token can never be transmitted for the SPNEGO mechanism [RFC4178].

      While a Java method can never return a value and throw an
      exception at the same time, we can embed the error token inside
      the exception so that the caller has a chance to retrieve it.
      This update adds a new GSSException constructor to include this
      token inside a GSSException object and a getOutputToken() method
      to retrieve the token.  The specification for the initSecContext
      and acceptSecContext methods are updated to describe the new
      behavior.  Various examples are also updated.

      New JGSS programs SHOULD make use of this new feature, but it is
      not mandatory.  A program that intends to run with both old and
      new GSS Java bindings can use reflection to check the availability
      of this new method and call it accordingly.

   2) Removing Stream-Based GSSContext Methods

      The overloaded methods of GSSContext that use input and output
      streams as the means to convey authentication and per-message
      GSS-API tokens as described in Section 5.15 of RFC 5653 [RFC5653]
      are removed in this update as the wire protocol should be defined
      by an application and not a library.  It's also impossible to
      implement these methods correctly when the token has no self-
      framing (where the end cannot be determined), or the library has
      no knowledge of the token format (for example, as a bridge talking
      to another GSS library).  These methods include initSecContext
      (Section 7.4.5 of RFC 5653 [RFC5653]), acceptSecContext
      (Section 7.4.9 of RFC 5653 [RFC5653]), wrap (Section 7.4.15 of RFC
      5653 [RFC5653]), unwrap (Section 7.4.17 of RFC 5653 [RFC5653]),
      getMIC (Section 7.4.19 of RFC 5653 [RFC5653]), and verifyMIC
      (Section 7.4.21 of RFC 5653 [RFC5653]).












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12.  Changes since RFC 2853

   This document has the following changes:

   1) Major GSS Status Code Constant Values

      RFC 2853 listed all the GSS status code values in two different
      sections: Section 4.12.1 defined numeric values for them, and
      Section 6.8.1 defined them as static constants in the GSSException
      class without assigning any values.  Due to an inconsistent
      ordering between these two sections, all of the GSS major status
      codes resulted in misalignment and a subsequent disagreement
      between deployed implementations.

      This document defines the numeric values of the GSS status codes
      in both sections, while maintaining the original ordering from
      Section 6.8.1 of RFC 2853 [RFC2853], and it obsoletes the GSS
      status code values defined in Section 4.12.1.  The relevant
      sections in this document are Sections 5.12.1 and 7.8.1.

   2) GSS Credential Usage Constant Values

      RFC 2853, Section 6.3.2 defines static constants for the
      GSSCredential usage flags.  However, the values of these constants
      were not defined anywhere in RFC 2853 [RFC2853].

      This document defines the credential usage values in
      Section 7.3.1.  The original ordering of these values from
      Section 6.3.2 of RFC 2853 [RFC2853] is maintained.

   3) GSS Host-Based Service Name

      RFC 2853 [RFC2853], Section 6.2.2 defines the static constant for
      the GSS host-based service OID NT_HOSTBASED_SERVICE, using a
      deprecated OID value.

      This document updates the NT_HOSTBASED_SERVICE OID value in
      Section 7.2.1 to be consistent with the C-bindings in RFC 2744
      [RFC2744].












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13.  References

13.1.  Normative References

   [RFC2025]  Adams, C., "The Simple Public-Key GSS-API Mechanism
              (SPKM)", RFC 2025, DOI 10.17487/RFC2025, October 1996,
              <https://www.rfc-editor.org/info/rfc2025>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC2743]  Linn, J., "Generic Security Service Application Program
              Interface Version 2, Update 1", RFC 2743,
              DOI 10.17487/RFC2743, January 2000,
              <https://www.rfc-editor.org/info/rfc2743>.

   [RFC2744]  Wray, J., "Generic Security Service API Version 2 :
              C-bindings", RFC 2744, DOI 10.17487/RFC2744, January 2000,
              <https://www.rfc-editor.org/info/rfc2744>.

   [RFC2853]  Kabat, J. and M. Upadhyay, "Generic Security Service API
              Version 2 : Java Bindings", RFC 2853,
              DOI 10.17487/RFC2853, June 2000,
              <https://www.rfc-editor.org/info/rfc2853>.

   [RFC4121]  Zhu, L., Jaganathan, K., and S. Hartman, "The Kerberos
              Version 5 Generic Security Service Application Program
              Interface (GSS-API) Mechanism: Version 2", RFC 4121,
              DOI 10.17487/RFC4121, July 2005,
              <https://www.rfc-editor.org/info/rfc4121>.

   [RFC4178]  Zhu, L., Leach, P., Jaganathan, K., and W. Ingersoll, "The
              Simple and Protected Generic Security Service Application
              Program Interface (GSS-API) Negotiation Mechanism",
              RFC 4178, DOI 10.17487/RFC4178, October 2005,
              <https://www.rfc-editor.org/info/rfc4178>.

   [RFC5653]  Upadhyay, M. and S. Malkani, "Generic Security Service API
              Version 2: Java Bindings Update", RFC 5653,
              DOI 10.17487/RFC5653, August 2009,
              <https://www.rfc-editor.org/info/rfc5653>.

   [RFC8174]  Leiba, B., "Ambiguity of Uppercase vs Lowercase in RFC
              2119 Key Words", BCP 14, RFC 8174, DOI 10.17487/RFC8174,
              May 2017, <https://www.rfc-editor.org/info/rfc8174>.




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13.2.  Informative References

   [ISOIEC-8824]
              International Organization for Standardization,
              "Information technology -- Abstract Syntax Notation One
              (ASN.1): Specification of basic notation", ISO/
              IEC 8824-1:2014, November 2015,
              <https://www.iso.org/standard/68350.html>.

   [ISOIEC-8825]
              International Organization for Standardization,
              "Information technology -- ASN.1 encoding rules:
              Specification of Basic Encoding Rules (BER), Canonical
              Encoding Rules (CER) and Distinguished Encoding Rules
              (DER)", ISO/IEC 8825-1:2015, November 2015,
              <https://www.iso.org/standard/68345.html>.

   [JLS]      Gosling, J., Joy, B., Steele, G., Bracha, G., Buckley, A.,
              and D. Smith, "The Java Language Specification", Java SE
              10 Edition, February 2018,
              <https://docs.oracle.com/javase/specs/jls/se10/html/
              index.html>.





























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Acknowledgments

   We would like to thank Mike Eisler, Lin Ling, Ram Marti, Michael
   Saltz, and other members of Sun's development team for their helpful
   input, comments, and suggestions.

   We would also like to thank Greg Hudson, Benjamin Kaduk, Joe Salowey
   and Michael Smith for many insightful ideas and suggestions that have
   contributed to this document.

Authors' Addresses

   Mayank D. Upadhyay
   Google Inc.
   1600 Amphitheatre Parkway
   Mountain View, CA  94043
   United States of America

   Email: m.d.upadhyay+ietf@gmail.com


   Seema Malkani
   ActivIdentity Corp.
   6623 Dumbarton Circle
   Fremont, California  94555
   United States of America

   Email: Seema.Malkani@gmail.com


   Weijun Wang
   Oracle
   Building No. 24, Zhongguancun Software Park
   Beijing  100193
   China

   Email: weijun.wang@oracle.com














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