One document matched: draft-ietf-cat-gssv2-javabind-01.txt
Differences from draft-ietf-cat-gssv2-javabind-00.txt
Internet-Draft Jack Kabat
IETF CAT Working Group ValiCert, Inc.
Document: <draft-ietf-cat-gssv2-javabind-01.txt> Mayank Upadhyay
Sun Microsystems, Inc.
March 1999
Generic Security Service API Version 2 : Java bindings
Status of this Memo
This document is an Internet-Draft and is in full conformance with
all provisions of Section 10 of RFC2026.
Internet-Drafts are working documents of the Internet Engineering
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The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt
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Abstract
The Generic Security Services Application Program Interface (GSS-API)
offers application programmers uniform access to security services
atop a variety of underlying cryptographic mechanisms. This document
specifies the Java bindings for GSS-API which is described at a
language independent conceptual level in RFC 2078 [GSSAPIv2].
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] and The Kerberos Version 5
GSS-API Mechanism [KERBV5].
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Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 6
2. GSS-API Operational Paradigm . . . . . . . . . . . . . . . . 6
3. GSS-API Classes . . . . . . . . . . . . . . . . . . . . . . 8
3.1. GSSCredential class . . . . . . . . . . . . . . . . . . . 8
3.2. GSSContext class . . . . . . . . . . . . . . . . . . . . . 9
3.3. GSSName class . . . . . . . . . . . . . . . . . . . . . 10
3.4. GSSManager class . . . . . . . . . . . . . . . . . . . . 11
3.5. GSSException class . . . . . . . . . . . . . . . . . . . 11
3.6. Oid class . . . . . . . . . . . . . . . . . . . . . . . 11
3.7. MessageProp class . . . . . . . . . . . . . . . . . . . 12
3.8. ChannelBinding class . . . . . . . . . . . . . . . . . . 12
4. Calling Conventions . . . . . . . . . . . . . . . . . . . 12
4.1. Integer types . . . . . . . . . . . . . . . . . . . . . 12
4.2. Opaque Data types . . . . . . . . . . . . . . . . . . . 13
4.3. Strings . . . . . . . . . . . . . . . . . . . . . . . . 13
4.4. Object Identifiers . . . . . . . . . . . . . . . . . . . 13
4.5. Object Identifier Sets . . . . . . . . . . . . . . . . . 13
4.6. Credentials . . . . . . . . . . . . . . . . . . . . . . 14
4.7. Contexts . . . . . . . . . . . . . . . . . . . . . . . . 16
4.8. Authentication tokens . . . . . . . . . . . . . . . . . 16
4.9. Interprocess tokens . . . . . . . . . . . . . . . . . . 16
4.10. Error Reporting . . . . . . . . . . . . . . . . . . . . 17
4.10.1. GSS status codes . . . . . . . . . . . . . . . . . . 17
4.10.2. Mechanism-specific status codes . . . . . . . . . . . 19
4.10.3. Supplementary status codes . . . . . . . . . . . . . 20
4.11. Names . . . . . . . . . . . . . . . . . . . . . . . . . 20
4.12. Channel Bindings . . . . . . . . . . . . . . . . . . . 23
4.13. Stream Objects . . . . . . . . . . . . . . . . . . . . 24
4.14. Optional Parameters . . . . . . . . . . . . . . . . . . 24
5. Additional Controls . . . . . . . . . . . . . . . . . . . 24
5.1. Delegation . . . . . . . . . . . . . . . . . . . . . . . 26
5.2. Mutual Authentication . . . . . . . . . . . . . . . . . 26
5.3. Replay and Out-of-Sequence Detection . . . . . . . . . . 27
5.4. Anonymous Authentication . . . . . . . . . . . . . . . . 28
5.5. Confidentiality . . . . . . . . . . . . . . . . . . . . 29
5.6. Inter-process Context Transfer . . . . . . . . . . . . . 29
5.7. The Use of Incomplete Contexts . . . . . . . . . . . . . 30
6. Detailed GSS-API Class Description . . . . . . . . . . . . 30
6.1. public class GSSName . . . . . . . . . . . . . . . . . . 30
6.1.1. Example Code . . . . . . . . . . . . . . . . . . . . . 30
6.1.2. Class Constants . . . . . . . . . . . . . . . . . . . 31
6.1.3. Constructors . . . . . . . . . . . . . . . . . . . . . 32
6.1.4. equals . . . . . . . . . . . . . . . . . . . . . . . . 34
6.1.5. equals . . . . . . . . . . . . . . . . . . . . . . . . 34
6.1.6. canonicalize . . . . . . . . . . . . . . . . . . . . . 34
6.1.7. export . . . . . . . . . . . . . . . . . . . . . . . . 35
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6.1.8. toString . . . . . . . . . . . . . . . . . . . . . . . 35
6.1.9. getStringNameType . . . . . . . . . . . . . . . . . . 35
6.1.10. clone . . . . . . . . . . . . . . . . . . . . . . . . 35
6.1.11. isAnonymous . . . . . . . . . . . . . . . . . . . . . 35
6.2. public class GSSCredential . . . . . . . . . . . . . . . 35
6.2.1. Example Code . . . . . . . . . . . . . . . . . . . . . 36
6.2.2. Class Constants . . . . . . . . . . . . . . . . . . . 37
6.2.3. Constructors . . . . . . . . . . . . . . . . . . . . . 37
6.2.4. dispose . . . . . . . . . . . . . . . . . . . . . . . 39
6.2.5. getGSSName . . . . . . . . . . . . . . . . . . . . . . 39
6.2.6. getGSSName . . . . . . . . . . . . . . . . . . . . . . 40
6.2.7. getRemainingLifetime . . . . . . . . . . . . . . . . . 40
6.2.8. getRemainingInitLifetime . . . . . . . . . . . . . . . 40
6.2.9. getRemainingAcceptLifetime . . . . . . . . . . . . . . 40
6.2.10. getUsage . . . . . . . . . . . . . . . . . . . . . . 41
6.2.11. getUsage . . . . . . . . . . . . . . . . . . . . . . 41
6.2.12. getMechs . . . . . . . . . . . . . . . . . . . . . . 41
6.2.13. add . . . . . . . . . . . . . . . . . . . . . . . . . 41
6.2.14. equals . . . . . . . . . . . . . . . . . . . . . . . 42
6.3. public class GSSContext . . . . . . . . . . . . . . . . 43
6.3.1. Example Code . . . . . . . . . . . . . . . . . . . . . 44
6.3.2. Class Constants . . . . . . . . . . . . . . . . . . . 45
6.3.3. Constructors . . . . . . . . . . . . . . . . . . . . . 46
6.3.4. init . . . . . . . . . . . . . . . . . . . . . . . . . 47
6.3.4.1. Example Code . . . . . . . . . . . . . . . . . . . . 47
6.3.5. init . . . . . . . . . . . . . . . . . . . . . . . . . 48
6.3.5.1. Example Code . . . . . . . . . . . . . . . . . . . . 49
6.3.6. accept . . . . . . . . . . . . . . . . . . . . . . . . 50
6.3.6.1. Example Code . . . . . . . . . . . . . . . . . . . . 50
6.3.7. accept . . . . . . . . . . . . . . . . . . . . . . . . 51
6.3.7.1. Example Code . . . . . . . . . . . . . . . . . . . . 52
6.3.8. isEstablished . . . . . . . . . . . . . . . . . . . . 52
6.3.9. dispose . . . . . . . . . . . . . . . . . . . . . . . 52
6.3.10. getWrapSizeLimit . . . . . . . . . . . . . . . . . . 53
6.3.11. wrap . . . . . . . . . . . . . . . . . . . . . . . . 53
6.3.12. wrap . . . . . . . . . . . . . . . . . . . . . . . . 54
6.3.13. unwrap . . . . . . . . . . . . . . . . . . . . . . . 55
6.3.14. unwrap . . . . . . . . . . . . . . . . . . . . . . . 56
6.3.15. getMIC . . . . . . . . . . . . . . . . . . . . . . . 56
6.3.16. getMIC . . . . . . . . . . . . . . . . . . . . . . . 57
6.3.17. verifyMIC . . . . . . . . . . . . . . . . . . . . . . 57
6.3.18. verifyMIC . . . . . . . . . . . . . . . . . . . . . . 58
6.3.19. export . . . . . . . . . . . . . . . . . . . . . . . 59
6.3.20. requestMutualAuth . . . . . . . . . . . . . . . . . . 60
6.3.21. requestReplayDet . . . . . . . . . . . . . . . . . . 60
6.3.22. requestSequenceDet . . . . . . . . . . . . . . . . . 60
6.3.23. requestCredDeleg . . . . . . . . . . . . . . . . . . 60
6.3.24. requestAnonymity . . . . . . . . . . . . . . . . . . 61
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6.3.25. requestConf . . . . . . . . . . . . . . . . . . . . . 61
6.3.26. requestInteg . . . . . . . . . . . . . . . . . . . . 61
6.3.27. requestLifetime . . . . . . . . . . . . . . . . . . . 62
6.3.28. setChannelBinding . . . . . . . . . . . . . . . . . . 62
6.3.29. getCredDelegState . . . . . . . . . . . . . . . . . . 62
6.3.30. getMutualAuthState . . . . . . . . . . . . . . . . . 62
6.3.31. getReplayDetState . . . . . . . . . . . . . . . . . . 63
6.3.32. getSequenceDetState . . . . . . . . . . . . . . . . . 63
6.3.33. getAnonymityState . . . . . . . . . . . . . . . . . . 63
6.3.34. isTransferable . . . . . . . . . . . . . . . . . . . 63
6.3.35. isProtReady . . . . . . . . . . . . . . . . . . . . . 63
6.3.36. getConfState . . . . . . . . . . . . . . . . . . . . 64
6.3.37. getIntegState . . . . . . . . . . . . . . . . . . . . 64
6.3.38. getLifetime . . . . . . . . . . . . . . . . . . . . . 64
6.3.39. getSrcName . . . . . . . . . . . . . . . . . . . . . 64
6.3.40. getTargName . . . . . . . . . . . . . . . . . . . . . 64
6.3.41. getMech . . . . . . . . . . . . . . . . . . . . . . . 65
6.3.42. getDelegCred . . . . . . . . . . . . . . . . . . . . 65
6.3.43. isInitiator . . . . . . . . . . . . . . . . . . . . . 65
6.4. public class MessageProp . . . . . . . . . . . . . . . . 65
6.4.1. Constructors . . . . . . . . . . . . . . . . . . . . . 66
6.4.2. getQOP . . . . . . . . . . . . . . . . . . . . . . . . 66
6.4.3. getPrivacy . . . . . . . . . . . . . . . . . . . . . . 66
6.4.4. setQOP . . . . . . . . . . . . . . . . . . . . . . . . 66
6.4.5. setPrivacy . . . . . . . . . . . . . . . . . . . . . . 67
6.4.6. isDuplicateToken . . . . . . . . . . . . . . . . . . . 67
6.4.7. isOldToken . . . . . . . . . . . . . . . . . . . . . . 67
6.4.8. isUnseqToken . . . . . . . . . . . . . . . . . . . . . 67
6.4.9. isGapToken . . . . . . . . . . . . . . . . . . . . . . 67
6.5. public class GSSManager . . . . . . . . . . . . . . . . 67
6.5.1. getMechs . . . . . . . . . . . . . . . . . . . . . . . 68
6.5.2. getNamesForMech . . . . . . . . . . . . . . . . . . . 68
6.5.3. getMechsForName . . . . . . . . . . . . . . . . . . . 68
6.5.4. getDefaultMech . . . . . . . . . . . . . . . . . . . . 68
6.6. public class ChannelBinding . . . . . . . . . . . . . . 68
6.6.1. Constructors . . . . . . . . . . . . . . . . . . . . . 69
6.6.2. getInitiatorAddress . . . . . . . . . . . . . . . . . 70
6.6.3. getAcceptorAddress . . . . . . . . . . . . . . . . . . 70
6.6.4. getApplicationData . . . . . . . . . . . . . . . . . . 70
6.6.5. equals . . . . . . . . . . . . . . . . . . . . . . . . 70
6.7. public class Oid . . . . . . . . . . . . . . . . . . . . 70
6.7.1. Constructors . . . . . . . . . . . . . . . . . . . . . 71
6.7.2. toString . . . . . . . . . . . . . . . . . . . . . . . 71
6.7.3. toRFC2078String . . . . . . . . . . . . . . . . . . . 72
6.7.4. equals . . . . . . . . . . . . . . . . . . . . . . . . 72
6.7.5. getDER . . . . . . . . . . . . . . . . . . . . . . . . 72
6.7.6. containedIn . . . . . . . . . . . . . . . . . . . . . 72
6.8. public class GSSException extends Exception . . . . . . 72
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6.8.1. Class Constants . . . . . . . . . . . . . . . . . . . 73
6.8.2. Constructors . . . . . . . . . . . . . . . . . . . . . 75
6.8.3. getMajor . . . . . . . . . . . . . . . . . . . . . . . 76
6.8.4. getMinor . . . . . . . . . . . . . . . . . . . . . . . 76
6.8.5. getMajorString . . . . . . . . . . . . . . . . . . . . 76
6.8.6. getMinorString . . . . . . . . . . . . . . . . . . . . 77
6.8.7. setMinor . . . . . . . . . . . . . . . . . . . . . . . 77
6.8.8. toString . . . . . . . . . . . . . . . . . . . . . . . 77
6.8.9. getMessage . . . . . . . . . . . . . . . . . . . . . . 77
7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . 77
8. Bibliography . . . . . . . . . . . . . . . . . . . . . . . 79
9. Author's Address . . . . . . . . . . . . . . . . . . . . . 80
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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 2078 [GSSAPIv2]. 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.
This document leverages on the work performed by the WG in the area
of RFC 2078 [GSSAPIv2] the C-bindings draft [GSSAPI-C]. Whenever
appropriate, text has been used from the C-bindings document to
explain generic concepts and provide direction to the implementors.
The design goals of this API have been to satisfy all the
functionality defined in RFC 2078 and to provide these services in an
object oriented method. Further, the 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. GSS-API Operational Paradigm
The Generic Security Service Application Programming Interface
[GSSAPIv2] 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.
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
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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 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, and
send the resulting token to the receiving application. The
receiver will pass the received token (and, in the case of
data protected by getMIC, the accompanying message-data) to
the corresponding decoding method of the GSSContext class
(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
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resources held. Multiple contexts may also be used (either
successively or simultaneously) within a single
communications association, at the discretion of the
applications.
3. GSS-API Classes
This section presents a brief description of the classes comprising
the GSS-API class library and the corresponding RFC 2078
functionality implemented by each of them. Detailed description of
all the classes and their corresponding methods is presented in
section 6.
3.1. GSSCredential class
The GSSCredential class 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 GSSCredential may contain
multiple mechanism specific credentials, each referred to as a
credential element. The GSSCredential class implements the
functionality of the following GSS-API routines:
RFC 2078 Routine Function Section(s)
gss_acquire_cred Acquire credential for use. 6.2.3
gss_add_cred Constructs credentials 6.2.13
incrementally.
gss_inquire_cred Obtain information about 6.2.5-6.2.12
credential.
gss_inquire_cred_by_mech Obtain per-mechanism 6.2.5-6.2.12
information about
a credential.
gss_release_cred Disposes of credentials 6.2.4
after use.
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3.2. GSSContext class
This class 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 class
implements the functionality of the following GSS-API routines:
RFC 2078 Routine Function Section(s)
gss_init_sec_context Initiate the creation of a 6.3.4,
security context with 6.3.5
a peer.
gss_accept_sec_context Accept a security context 6.3.6,
initiated by a peer. 6.3.7
gss_delete_sec_context Destroy a security context. 6.3.9
gss_context_time Obtain remaining context 6.3.38
time.
gss_inquire_context Obtain context 6.3.38 to
characteristics. 6.3.43
gss_wrap_size_limit Determine token-size limit 6.3.10
for gss_wrap.
gss_export_sec_context Transfer security context 6.3.19
to another process.
gss_import_sec_context Create a previously exported 6.3.3
context.
gss_get_mic Calculate a cryptographic 6.3.15,
Message Integrity Code (MIC) 6.3.16
for a message.
gss_verify_mic Verify integrity on a received 6.3.17,
message. 6.3.18
gss_wrap Attach a MIC to a message and 6.3.11,
optionally encrypt the message 6.3.12
content.
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gss_unwrap Obtain a previously wrapped 6.3.13,
application message verifying 6.3.14
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
accordance to the recommendations stated in the RFC 2078 update
draft. GSSContext does offer the functionality of destroying the
locally-stored context information.
3.3. GSSName class
GSS-API names are represented in the Java bindings through the
GSSName class. Different name formats and their definitions are
identified with universal Object Identifiers (oids). The format of
the names can be derived based on the unique oid of each name type.
The following GSS-API routines are implemented by the GSSName object:
RFC 2078 Routine Function Section(s)
gss_import_name Create an internal name from 6.1.3
the supplied information.
gss_display_name Covert internal name 6.1.8, 6.1.9
representation to text format.
gss_compare_name Compare two internal names. 6.1.4, 6.1.5
gss_release_name Release resources associated N/A
with the internal name.
gss_canonicalize_name Convert an internal name to a 6.1.3, 6.1.6
mechanism name.
gss_export_name Convert a Mechanism name to 6.1.7
export format.
gss_duplicate_name Create a copy of the internal 6.1.10
name.
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3.4. GSSManager class
The responsibilities of the GSSManager class is to provide
functionality common to the entire GSS-API class library. This would
include queries about the mechanisms supported and the default
mechanism value. GSSManager implements the following RFC 2078
routines:
RFC 2078 Routine Function Section
gss_inquire_names_for_mech List the name types 6.5.2
supported by the
specified mechanism.
gss_inquire_mechs_for_name List the mechanisms 6.5.3
supporting the
specified name type.
gss_indicate_mechs List the mechanisms 6.5.1
supported by this GSS-API
implementation.
3.5. 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 possibly throwing this exception.
RFC 2078 Routine Function Section
gss_display_status Retrieve textual 6.8.5, 6.8.6,
representation of error 6.8.8, 6.8.9
codes.
3.6. 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:
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RFC 2078 Routine Function Section
gss_test_oid_set_member Determine if the specified oid 6.7.6
is part of a set of oids.
3.7. MessageProp class
This helper class is used in the per-message operations of the
GSSContext class to convey the requested and applied per-message
options. An instance of this class is used to specify the desired QOP
and confidentiality state for a per-message operation of the
GSSContext class. Upon return from those methods, this object will
contain the applied QOP and confidentiality state as well as any
supplementary status information for the completed per-message
operation.
3.8. 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
using 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.
4. Calling Conventions
Java provides the implementors with more than 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.
4.1. Integer types
All numeric values are declared as "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.
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4.2. Opaque Data types
Java byte arrays are used to represent opaque data types which are
consumed and produced by the GSS-API in the forms of tokens. Java
arrays contain a length field which enables the users to easily
determine their size. The language has automatic garbage collection
which alleviates the need by developers to release memory and
simplifies buffer ownership issues.
4.3. 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.
4.4. 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.
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. 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.
4.5. Object Identifier Sets
The Java bindings represents object identifiers 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 2078, the Oid class
includes a method which 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
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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 complicated memory management issues
of the C counterpart.
When ever a default value for an Object Identifier Set is required, a
"null" value can be used. Please consult the detailed method
description for details.
4.6. Credentials
GSS-API credentials are represented with the GSSCredential object.
The object contains several constructs to allow for the creation of
most common credential objects for the initiator and the acceptor.
Comparisons are performed using the object's "equals" method. The
following general description of GSS-API credentials is included from
the C-bindings specification:
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 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 constructor's for the GSSContext object allow the value of "null"
to be specified as their 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:
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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.
and 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
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
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whenever possible. Applications requesting default behavior are
likely to be more portable across mechanisms and implementations than
ones that instantiate a GSSCredential representing a specific
identity.
4.7. Contexts
The GSSContext class 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.
GSSContext class has distinct constructors to allow the creation of
an initiator and acceptor side of the contexts. After the context has
been instantiated, the initiator may choose to set various context
options which will determine the characteristics of the desired
security context. When all the application desired characteristics
have been set, the initiator will call the init method which will
produce a token for consumption by the peer's accept 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. At this point the context can be used by the application to
apply cryptographic services to its data.
4.8. 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.
Overloaded methods exist which allow the caller to supply input and
output streams which will be used for the reading and writing of the
token data.
4.9. Interprocess tokens
Certain GSS-API routines are intended to transfer data between
processes in multi-process programs. These routines use a caller-
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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 interprocess 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 interprocess
tokens are protected in transit, and transferred only to processes
that are trustworthy. An interprocess token is represented using a
byte array emitted from the export method of the GSSContext class.
The receiver of the interprocess token would use a GSSContext
constructor to create a new context object from the supplied token.
Once a context has been exported, the GSSContext object is
invalidated and is no longer available.
4.10. Error Reporting
RFC 2078 defined the usage of major and minor status values for
signaling of GSS-API errors. The major code, also called 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. GSSException class also
contains methods to obtain textual representations for both the major
and minor values, which is equivalent to the functionality of
gss_display_status.
4.10.1. 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). The Java bindings take advantage of the strong type
checking of the Java language, 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
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that a fatal error has occurred during the execution of the method.
Several GSS-API routines can also return supplementary status
information which indicate non-fatal errors. These are 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 limited to the per-message
methods of the GSSContext class, namely verifyMIC and unwrap. These
methods return an instance of MessageProp class which contains the
specific supplementary error information.
GSSException object, along with providing the functionality for
setting of 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:
Table: GSS Status Codes
Name Value Meaning
BAD_MECH 1 An unsupported mechanism
was requested.
BAD_NAME 2 An invalid name was supplied.
BAD_NAMETYPE 3 A supplied name was of an
unsupported type.
BAD_BINDINGS 4 Incorrect channel bindings were
supplied.
BAD_STATUS 5 An invalid status code was
supplied.
BAD_MIC 6 A token had an invalid MIC.
NO_CRED 7 No credentials were supplied, or
the credentials were unavailable
or inaccessible.
NO_CONTEXT 8 Invalid context has been
supplied.
DEFECTIVE_TOKEN 9 A supplied token was invalid.
DEFECTIVE_CREDENTIAL 10 A supplied credential was
invalid.
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CREDENTIALS_EXPIRED 11 The referenced credentials
have expired.
CONTEXT_EXPIRED 12 The context has expired.
FAILURE 13 Miscellaneous failure,
unspecified at the GSS-API level.
BAD_QOP 14 The quality-of-protection
requested could not be provided.
UNAUTHORIZED 15 The operation is forbidden by
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.
OLD_TOKEN 19 The token's validity period has
expired.
DUPLICATE_TOKEN 20 The token was a duplicate of an
earlier version.
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.
4.10.2. Mechanism-specific status codes
The GSSException thrown from a GSS-API method may originate from the
mechanism independent layer or the mechanism specific layer. In the
latter case, the exception will be used to indicate not only the
major error codes but also the mechanism specific error code.
A default value of 0 will be used to represent the absence of the
mechanism specific status code.
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4.10.3. Supplementary status codes
Supplementary status codes are confined to the per-message methods of
the GSSContext class. 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 class return an
instance of a MessageProp class which contain supplementary status
information.
The MessageProp class defines query methods which 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.
"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.
4.11. 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:
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1) A GSS-API form represented by instances of the GSSName class: 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 class, 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 object implementations must contain sufficient
information to determine the namespace to which each primitive
name belongs.
2) Mechanism-specific contiguous byte array and string forms:
Different GSSName constructors 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 class).
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 constructors for the
GSSName object are defined allowing support for multiple syntaxes for
each supported namespace, and allowing 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, getStringNameType method can be
used.
There is no guarantee that calling the toString method on a GSSName
object 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 name-
space 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
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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 an instance of GSSName representing
the entity performing the context initiation (through the usage of
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 "MN"s and the names emitted by GSSContext class
in the getSrcName and getTargName are always of this type. Since
some applications may require MNs without wanting to incur the
overhead of an authentication operation, a set of constructors is
provided which 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.
When used in large access control lists, the overhead of creating a
GSSName on each name and invoking the equal method on each name from
the 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, which
requires that the GSSName represent a MN. 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 a MN. The GSSName object 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
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description of the format is specified in the language-independent
GSS-API specification [GSSAPIv2].
Note that the results obtained by using the equal 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 same principal; the second 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 how GSSName
objects should behave, and are not intended to be specific
requirements of how names objects must be implemented. The mechanism
designers are free to decide on the details of their implementations
of the GSSName object as long as the behavior satisfies the above
guidelines.
4.12. 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 to specify
the application data to be used in the channel binding as well as
using instances of the InetAddress. 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 an instance of GSSContext method, "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.
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 MIC over this octet
string and binds the MIC to the context establishment token emitted
by init method of the GSSContext class. 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
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(rather than just a MIC); applications should therefore not use
confidential data as channel-binding components.
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 setting of the addressing
information.
4.13. Stream Objects
The GSSContext object provides overloaded methods which use input and
output streams as the means to convey authentication and per-message
GSS-API tokens. It is important to note that the streams are expected
to contain the usual GSS-API tokens which would otherwise be handled
through the usage of byte arrays. The tokens are expected to have a
definite start and an end. The callers are responsible for ensuring
that the supplied streams will not block, or expect to block until a
full token is processed by the GSS-API method. Only a single GSS-API
token will be processed per invocation of the stream based method.
The usage of streams allows the callers to have control and
management of the supplied buffers. Because streams are non-primitive
objects, the callers can make the streams as complicated or as simple
as desired simply by using the streams defined in the java.io package
or creating their own through the use of inheritance. This will allow
for the application's greatest flexibility.
4.14. 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. Methods overloading has also
been used as a technique to indicate default parameters.
5. 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.
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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 class offers query methods to allow the 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 may
apply to any of the services. Such mechanisms are required to send
at least one token from acceptor to initiator during context
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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.
5.1. 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 class. In cases when it
is, 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
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 over-ride 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.
5.2. Mutual Authentication
Usually, a context acceptor will require that a context initiator
authenticate itself so that the acceptor may make an access-control
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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 class 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.
5.3. 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 class, and verified by the peer application
by calling verifyMIC or unwrap for the peer's GSSContext object.
getMIC calculates a cryptographic checksum 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.
wrap 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 duplication of messages. Details of such mis-
ordered messages are indicated through supplementary query methods of
the MessageProp object returned from 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 a isOldToken method of
the instance of MessageProp to return "true".
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5.4. 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
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
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 class, and one of the
operands is a GSSName instance representing an anonymous entity, the
method must return "false".
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5.5. Confidentiality
If a GSSContext supports the confidentiality service, 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 within the wrap method.
5.6. Inter-process Context Transfer
GSS-API V2 provides functionality which 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 GSSContext class provides 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 re-create 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 class will indicate if the context object is
transferable.
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5.7. 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.
6. Detailed GSS-API Class Description
This section lists a detailed description of all the public methods
that each of the GSS-API classes must provide.
6.1. public class GSSName
An object of this class encapsulates a single GSS-API principal
entity. Different name formats and their definitions are identified
with universal Object Identifiers (Oids). The format of the names can
be derived based on the unique oid of each name type.
6.1.1. Example Code
Included below are code examples utilizing the GSSName object. The
code below creates a GSSName object, converts it to a mechanism name
(MN), performs a comparison, obtains a printable representation of
the name, exports it and then re-imports to obtain a new GSSName
object.
//create an oid object for Kerberos v5
Oid krb5 = new Oid("1.2.840.113554.1.2.2");
//create a service name, and convert it to a mechanism name
GSSName aName = new GSSName("service@host",
GSSName.NT_HOSTBASED_SERVICE);
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GSSName mechName = aName.canonicalize(krb5);
//the above two steps are equivalent to the following constructor
GSSName mechName = new GSSName("service@host",
GSSName.NT_HOSTBASED_SERVICE,
krb5);
//perform name comparison
if (aName.equals(mechName))
print("Names are equals.");
//obtain textual representation of name and its printable
//name type
print(mechName.toString() +
mechName.getStringNameType().toString());
//export and re-import the name
byte [] exportName = mechName.export();
//create a new name object from the exported buffer
GSSName newName = new GSSName(exportName,
GSSName.NT_EXPORT_NAME);
6.1.2. Class 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: { 1(iso), 3(org), 6(dod),
1(internet), 5(security), 6(nametypes), 2(gss-host-based-services) }
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) }
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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) }
public static final Oid NT_ANONYMOUS
Name type for representing an anonymous entity. It represents the
following value: { 1(iso), 3(org), 6(dod), 1(internet), 5(security),
6(nametypes), 3(gss-anonymous-name) }
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: { 1(iso), 3(org), 6(dod),
1(internet), 5(security), 6(nametypes), 4(gss-api-exported-name) }
6.1.3. Constructors
public GSSName(String nameStr, Oid type) throws GSSException
Converts a contiguous string name to a GSSName object of the
specified type. The nameStr parameter is interpreted based on the
type specified. In general, the GSSName object created will not be
an MN; the exception to this is if the type parameter indicates
NT_EXPORT_NAME.
Parameters:
nameStr The string representing the name to create.
type Oid specifying type of the printable name supplied.
"null" value can be used to specify a default
printable syntax.
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public GSSName(byte name[], Oid type) throws GSSException
Converts a contiguous byte name to a GSSName object of the specified
type. The name parameter is interpreted based on the type specified.
This constructor is provided for use with names that aren't expressed
as printable strings (for example, names of type NT_EXPORT_NAME). In
general, the GSSName object created will not be an MN.
Parameters:
name The byte array representing the name to create.
type Oid specifying the type of name supplied. "null" value
can be used to specify a default syntax.
public GSSName(String nameStr, Oid nameType, Oid mechType)
throws GSSException
Converts a contiguous string name to a GSSName object of the
specified type. The nameStr parameter is interpreted based on the
type specified. This constructor is provided to allow the creation of
mechanism-specific names without having to call canonicalize.
Parameters:
nameStr The string representing the name to create.
nameType Oid specifying type of the printable name supplied.
"null" value can be used to specify a default
printable syntax.
mechType Oid specifying the mechanism for which this name
should be created. "null" value can be used to specify
the default mechanism.
public GSSName(byte name[], Oid nameType, Oid mechType)
throws GSSException
Converts a contiguous byte name to a GSSName object of the specified
type. The name parameter is interpreted based on the type specified.
This constructor is provided to be used with names that aren't
expressed as printable strings. It allows the creation of
mechanism-specific names without having to call canonicalize.
Parameters:
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name The byte array representing the name to create.
type Oid specifying the type of name supplied. "null" value
can be used to specify a default syntax.
mechType Oid specifying the mechanism for which this name
should be created. "null" value can be used to specify
the default mechanism.
6.1.4. equals
public boolean equals(Object another)
Compares two GSSName objects to determine whether they refer to the
same entity. If either of the names is of the NT_ANONYMOUS type,
this call will return "false".
Parameters:
another GSSName object to compare with.
6.1.5. equals
public boolean equals(GSSName another) throws GSSException
A variation of equals method which 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 to compare with.
6.1.6. canonicalize
public GSSName canonicalize(Oid mechOid) throws GSSException
Creates a mechanism name (MN) from an arbitrary internal name. This
is equivalent to using a constructor which takes the mechanism name
as one of its parameters.
Parameters:
mechOid The oid for the authentication mechanism for which the
canonical form of the name is requested.
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6.1.7. export
public byte[] export() throws GSSException
Returns a canonical contiguous byte representation of a mechanism
name (MN), suitable for direct, byte by byte comparison by
authorization functions. The name must a MN before calling this
method. The format of the header of the outputted buffer is specified
in RFC 2078.
6.1.8. 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.
6.1.9. 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.
6.1.10. clone
public Object clone() throws CloneNotSupportedException
Creates a duplicate copy of this name.
6.1.11. isAnonymous
public boolean isAnonymous()
Tests if this name object represents an anonymous entity. Returns
"true" if this is an anonymous name.
6.2. public class GSSCredential
This class manages GSS-API credentials and their associated
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operations. 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. GSSCredential 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 the GSSContext object). 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 GSSCredential 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.
6.2.1. Example Code
This example code demonstrates the creation of a GSSCredential object
for a specific entity, querying of its fields, and its release when
it is no longer needed.
//start by creating a name object for the entity
GSSName aName = new GSSName("userName", GSSName.NT_USER_NAME);
GSSCredential entity = new GSSCredential(
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aName,
GSSCredential.ACCEPT_ONLY);
//display credential information - name, remaining lifetime,
//and the mechanisms it has been acquired over
print(entity.getGSSName().toString());
print(entity.getRemainingLifetime());
Oid [] mechs = entity.getMechs();
if (mechs != null) {
for (int i = 0; i < mechs.length; i++)
print(mechs[i].toString());
}
//release system resources held by the credential
entity.dispose();
6.2.2. Class 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.
public static final int INITIATE_ONLY
Credential usage flag requesting that it be able to be used for
context initiation only.
public static final int ACCEPT_ONLY
Credential usage flag requesting that it be able to be used for
context acceptance only.
public static final int INDEFINITE
A lifetime constant representing indefinite credential lifetime.
This value must be set to the maximum integer value in Java -
Integer.MAX_VALUE.
6.2.3. Constructors
public GSSCredential(int usage) throws GSSException
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Constructor for default credentials. This will use the default
mechanism, name, and an INDEFINITE lifetime.
Parameters are:
usage The intended usage for this credential object. The
value of this parameter must be one of:
GSSCredential.ACCEPT_AND_INITIATE,
GSSCredential.ACCEPT_ONLY, GSSCredential.INITIATE_ONLY
public GSSCredential(GSSName aName, int usage) throws GSSException
Constructor for default mechanism credential. Uses default mechanism
and INDEFINITE lifetime.
Parameters are:
aName Name of the principal for whom this credential is to
be acquired.
usage The intended usage for this credential object. The
value of this parameter must be one of:
GSSCredential.ACCEPT_AND_INITIATE,
GSSCredential.ACCEPT_ONLY, GSSCredential.INITIATE_ONLY
public GSSCredential(GSSName aName, int lifetime, Oid mechOid,
int usage) throws GSSException
Constructor for a single mechanism credential. "null" values can be
specified for name and mechanism to obtain system specific defaults.
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 to request that
the credentials have the maximum permitted lifetime.
mechOid The oid of the desired mechanism.
usage The intended usage for this credential object. The
value of this parameter must be one of:
GSSCredential.ACCEPT_AND_INITIATE,
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GSSCredential.ACCEPT_ONLY, GSSCredential.INITIATE_ONLY
public GSSCredential(GSSName aName, int lifetime, Oid mechs[],
int usage) throws GSSException
Constructor for a credential over a set of mechanisms. Acquires
credentials for each of the mechanisms specified in mechs array.
"null" value can be used for aName to obtain system specific default.
To determine which mechanism's acquisition of the credential was
successful use the getMechs method. This call is equivalent to
creating a single mechanism credential and using addCred to extend
the credential over other mechanisms.
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 to request that
the credentials have the maximum permitted lifetime.
mechOid The array of 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.ACCEPT_AND_INITIATE,
GSSCredential.ACCEPT_ONLY, GSSCredential.INITIATE_ONLY
6.2.4. dispose
public void dispose() throws GSSException
Releases any sensitive information that the GSSCredential may be
containing. Applications should call this method as soon as the
credential is no longer needed to minimize the time sensitive
information is maintained.
6.2.5. getGSSName
public GSSName getGSSName() throws GSSException
Retrieves the name of the entity that the credential asserts.
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6.2.6. getGSSName
public GSSName getGSSName(Oid mechOID) throws GSSException
Retrieves per-mechanism name of the entity that the credential
asserts.
Parameters:
mechOID The mechanism for which information should be
returned.
6.2.7. 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
indicates that the credential does not expire. A return value of 0
indicates that the credential is already expired.
6.2.8. getRemainingInitLifetime
public int getRemainingInitLifetime(Oid mech) throws GSSException
Returns the remaining lifetime is seconds for the credential to
remain capable of initiating security contexts under the specified
mechanism. A return value of GSSCredential.INDEFINITE 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.
6.2.9. getRemainingAcceptLifetime
public int getRemainingAcceptLifetime(Oid mech) throws GSSException
Returns the remaining lifetime is seconds for the credential to
remain capable of accepting security contexts under the specified
mechanism. A return value of GSSCredential.INDEFINITE indicates that
the credential does not expire for context acceptance. A return value
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of 0 indicates that the credential is already expired.
Parameters:
mechOID The mechanism for which information should be
returned.
6.2.10. getUsage
public int getUsage() throws GSSException
Returns the credential usage flag. The return value will be one of
GSSCredential.INITIATE_ONLY, GSSCredential.ACCEPT_ONLY, or
GSSCredential.INITIATE_AND_ACCEPT.
6.2.11. getUsage
public int getUsage(Oid mechOID) throws GSSException
Returns the credential usage flag for the specified credential
mechanism. The return value will be one of
GSSCredential.INITIATE_ONLY, GSSCredential.ACCEPT_ONLY, or
GSSCredential.INITIATE_AND_ACCEPT.
Parameters:
mechOID The mechanism for which information should be
returned.
6.2.12. getMechs
public Oid[] getMechs() throws GSSException
Returns an array of mechanisms supported by this credential.
6.2.13. 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. This functionality is equivalent to using the
GSSCredential constructor which takes an Oid array as an input
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parameter or calling this method once for each of the mechanisms in
the array.
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.
To obtain a new credential object after the addition of the new
mechanism credential, the clone method can be called.
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 of security contexts. Use
GSSCredential.INDEFINITE to request that the
credentials have the maximum permitted lifetime.
acceptLifetime
The number of seconds that credentials should remain
valid for accepting of security contexts. Use
GSSCredential.INDEFINITE to request that the
credentials have the maximum permitted lifetime.
mechOid 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.ACCEPT_AND_INITIATE,
GSSCredential.ACCEPT_ONLY, GSSCredential.INITIATE_ONLY
6.2.14. equals
public boolean equals(Object another)
Tests if this GSSCredential refers to the same entity as the supplied
object. The two GSSCredentials 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; "false" otherwise.
Parameter:
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another Another GSSCredential object for comparison.
6.3. public class GSSContext
This class represents the GSS-API security context and its associated
operations. Security contexts are established between peers using
locally acquired credentials. Multiple contexts may exist
simultaneously between a pair of peers, using the same or 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.
The GSSContext object can be thought of as having 3 implicit states:
before it is established, during its context establishment, and after
a fully established context exists.
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 init and
accept methods will produce GSS-API authentication tokens which the
calling application needs to send to its peer. The init and accept
methods may return a CONTINUE_NEEDED code which indicates that a
token is needed from its peer in order to continue the context
establishment phase. A return code of COMPLETE signals that the local
end of the context is established. This may still require that a
token be sent to the peer, depending if one is produced by GSS-API.
The isEstablished method can also be used to determine if the local
end of the context has been fully established. 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 implementation to use per-message operations on contexts
which 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.
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When the context is no longer needed, the application should call
dispose to release any system resources the context may be using.
6.3.1. Example Code
The example code presented below demonstrates the usage of the
GSSContext object 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.
//start by creating the name for a service entity
GSSName targetName = new GSSName("service@host",
GSSName.NT_HOSTBASED_SERVICE);
//create a context using default credentials for the
//default mechanism
GSSContext aCtxt = new GSSContext(targetName,
null, /* default mechanism */
null, /* default credentials */
GSSContext.INDEFINITE);
//set desired context options - all others are false by default
aCtxt.requestConf(true);
aCtxt.requestMutualAuth(true);
aCtxt.requestReplayDet(true);
aCtxt.requestSequenceDet(true);
//establish a context between peers - using byte arrays
byte []inTok = new byte[0];
try {
do {
byte[] outTok = aCtxt.init(inTok, 0, inTok.length);
//send the token if present
if (outTok != null)
sendToken(outTok);
//check if we should expect more tokens
if (aCtxt.isEstablished())
break;
//another token expected from peer
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inTok = readToken();
} while (true);
} catch (GSSException e) {
print("GSSAPI error: " + e.getMessage());
}
//display context information
print("Remaining lifetime in seconds = " + aCtxt.getLifetime());
print("Context mechanism = " + aCtxt.getMech().toString());
print("Initiator = " + aCtxt.getSrcName().toString());
print("Acceptor = " + aCtxt.getTargName().toString());
if (aCtxt.getConfState())
print("Confidentiality security service available");
if (aCtxt.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);
byte []tok = aCtxt.wrap(appMsg, 0, appMsg.length, mProp);
if (mProp.getPrivacy())
print("Message protected with privacy.");
sendToken(tok);
//release the local-end of the context
aCtxt.dispose();
6.3.2. Class Constants
public static final int INDEFINITE
A lifetime constant representing indefinite context lifetime. This
value must be set to the maximum integer value in Java -
Integer.MAX_VALUE.
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public static final int COMPLETE
Return value from either accept or init stating that the context
creation phase is complete for this peer.
public static final int CONTINUE_NEEDED
Return value from either accept or init stating that another token is
required from the peer to continue context creation. This may be
returned several times indicating multiple token exchanges.
6.3.3. Constructors
public GSSContext(GSSName peer, Oid mechOid, GSSCredential myCred,
int lifetime) throws GSSException
Constructor for creating a context on the initiator's side. Context
flags may be modified through the mutator methods prior to calling
init.
Parameters:
peer Name of the target peer.
mechOid Oid of the desired mechanism. Use "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 credential.
public GSSContext(GSSCredential myCred) throws GSSException
Constructor for creating a context on the acceptor' 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.
public GSSContext(byte [] interProcessToken) throws GSSException
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Constructor for creating 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.
6.3.4. init
public byte[] init(byte inputBuf[], int offset, int len)
throws GSSException
Called by the context initiator to start the context creation
process. This is equivalent to the stream based method except that
the token buffers are handled as byte arrays instead of using stream
objects. This method may return an output token which the application
will need to send to the peer for processing by the accept call.
"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 the init method. Please note that the init method
may return a token for the peer, and isEstablished 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.
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).
6.3.4.1. Example Code
//create a GSSContext object
GSSContext aCtxt = new GSSContext(...
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byte []inTok = new byte[0];
try {
do {
byte[] outTok = aCtxt.init(inTok, 0,
inTok.length);
//send the token if present
if (outTok != null)
sendToken(outTok);
//check if we should expect more tokens
if (aCtxt.isEstablished())
break;
//another token expected from peer
inTok = readToken();
} while (true);
} catch (GSSException e) {
print("GSSAPI error: " + e.getMessage());
}
6.3.5. init
public int init(InputStream inputBuf, OutputStream outputBuf)
throws GSSException
Called by the context initiator to start the context creation
process. This is equivalent to the byte array based method. This
method may write an output token to the outputBuf, which the
application will need to send to the peer for processing by the
accept call. 0 bytes written to the output stream indicate that no
token needs to be sent to the peer. The method will return either
COMPLETE or CONTINUE_NEEDED indicating the status of the current
context. A return value of COMPLETE indicates that the context
establishment phase is complete for this peer, while CONTINUE_NEEDED
means that another token is expected from the peer. The isEstablished
method can also be used to determine this state. Note that it is
possible to have a token for the peer while this method returns
COMPLETE. This indicates that the local end of the context is
established, but the token needs to be sent to the peer to complete
the context establishment.
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The GSS-API authentication tokens contain a definitive start and end.
This method will attempt to read one of these tokens per invocation,
and may block on the stream if only part of the token is available.
Upon completion of the context establishment, the available context
options may be queried through the get methods.
Parameters:
inputBuf Contains the token generated by the peer. This
parameter is ignored on the first call.
outputBuf Buffer where the output token will be written. During
the final stage of context establishment, there may be
no bytes written.
6.3.5.1. Example Code
//create a GSSContext object
GSSContext aCtxt = new GSSContext(...
//use standard java.io stream objects
ByteArrayOutputStream os = new ByteArrayOutputStream();
ByteArrayInputStream is = null;
try {
while (aCtxt.init(is, os) ==
GSSContext.CONTINUE_NEEDED) {
//send token to peer
sendToken(os);
//another token expected from peer
is = recvToken();
}
//send token if present
if (os.size() > 0)
sendToken(os);
} catch (GSSException e) {
print("GSS-API error: " + e.getMessage());
}
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6.3.6. accept
public byte[] accept(byte inTok[], int offset, int len)
throws GSSException
Called by the context acceptor upon receiving a token from the peer.
This call is equivalent to the stream based method except that the
token buffers are handled as byte arrays instead of using stream
objects.
This method may return an output token which the application will
need to send to the peer for further processing by the init call.
"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.
Please note that the accept method may return a token for the peer,
and isEstablished 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.
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).
6.3.6.1. Example Code
//obtain server credentials
GSSCredential server = ...
//create acceptor GSS-API context
GSSContext aCtxt = new GSSContext(server);
try {
do {
byte [] inTok = readToken();
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byte []outTok = aCtxt.accept(inTok, 0,
inTok.length);
//possibly send token to peer
if (outTok != null)
sendToken(outTok);
//check if local context establishment is complete
if (aCtxt.isEstablished())
break;
} while (true);
} catch (GSSException e) {
print("GSS-API error: " + e.getMessage());
}
6.3.7. accept
public int accept(InputStream inputBuf, OutputStream outputBuf)
throws GSSException
Called by the context acceptor upon receiving a token from the peer.
This call is equivalent to the byte array method. It may write an
output token to the outputBuf, which the application will need to
send to the peer for processing by its init method. 0 bytes written
to the output stream indicate that no token needs to be sent to the
peer. The method will return either COMPLETE or CONTINUE_NEEDED
indicating the status of the current context. A return value of
COMPLETE indicates that the context establishment phase is complete
for this peer, while CONTINUE_NEEDED means that another token is
expected from the peer. The isEstablished method can also be used to
determine this state. Note that it is possible to have a token for
the peer while this method returns COMPLETE. This indicates that the
local end of the context is established, but the token needs to be
sent to the peer to complete the context establishment.
The GSS-API authentication tokens contain a definitive start and end.
This method will attempt to read one of these tokens per invocation,
and may block on the stream if only part of the token is available.
Upon completion of the context establishment, the available context
options may be queried through the get methods.
Parameters:
inputBuf Contains the token generated by the peer.
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outputBuf Buffer where the output token will be written. During
the final stage of context establishment, there may be
no bytes written.
6.3.7.1. Example Code
//obtain server credentials
GSSCredential server = ...
//create acceptor GSS-API context
GSSContext aCtxt = new GSSContext(server);
//use standard java.io stream objects
ByteArrayOutputStream os = new ByteArrayOutputStream();
ByteArrayInputStream is = null;
int retCode;
try {
do {
is = recvToken();
retCode = aCtxt.accept(is, os);
//possibly send token to peer
if (os.size() > 0)
sendToken(os);
} while (retCode == GSSContext.CONTINUE_NEEDED);
} catch (GSSException e) {
print("GSS-API error: " + e.getMessage());
}
6.3.8. isEstablished
public boolean isEstablished()
Returns "true" if this is a fully established context. Used after the
init and accept methods to check if more tokens are needed from the
peer.
6.3.9. dispose
public void dispose() throws GSSException
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Releases any system resources and cryptographic information stored in
the context object. This will invalidate the context.
6.3.10. 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.
6.3.11. wrap
public byte[] wrap(byte inBuf[], int offset, int len,
MessageProp msgProp) throws GSSException
Allows to apply per-message security services over the established
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security context. The method will return a token with a cryptographic
MIC and may optionally encrypt the specified inBuf. This method is
equivalent in functionality to its stream counterpart. The returned
byte array will contain both the MIC and the message. The msgProp
object is used to specify a QOP value which selects cryptographic
algorithms, and a privacy service, if supported by the chosen
mechanism.
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 containing the desired QOP and
privacy state. Upon return from this method, this
object will contain the applied QOP (for cases when 0
was used) and the actual privacy state of the token.
6.3.12. wrap
public void wrap(InputStream inBuf, OutputStream outBuf,
MessageProp msgProp) throws GSSException
Allows to apply per-message security services over the established
security context. The method will produce a token with a
cryptographic MIC and may optionally encrypt the specified inBuf.
The outBuf will contain both the MIC and the message. The msgProp
object is used to specify a QOP value to select cryptographic
algorithms, and a privacy service, if supported by the chosen
mechanism.
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
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peer.
Parameters:
inpBuf Application data to be protected.
outBuf The buffer to write the protected message to. The
application is responsible for sending this to the
other peer for processing in its unwrap method.
msgProp Instance of MessageProp containing the desired QOP and
privacy state. Upon return from this method, this
object will contain the applied QOP (for cases when 0
was used) and the actual privacy state of the token.
6.3.13. 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. This call is equal in functionality to its stream
counterpart. The method will return the message supplied in the peer
application to the wrap call, verifying the embedded MIC. The
msgProp instance will indicate whether the message was encrypted and
will contain the QOP indicating the strength of protection that was
used to provide the confidentiality and integrity services.
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 and the privacy state of the supplied
token.
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6.3.14. unwrap
public void unwrap(InputStream inBuf, OutputStream outBuf,
MessageProp msgProp) throws GSSException
Used by the peer application to process tokens generated with the
wrap call. This call is equal in functionality to its byte array
counterpart. It will produce the message supplied in the peer
application to the wrap call, verifying the embedded MIC. The
msgProp parameter will indicate whether the message was encrypted and
will contain the QOP indicating the strength of protection that was
used to provide the confidentiality and integrity services. The
msgProp object will also contain the supplementary status information
for the token.
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.
outBuf The buffer to write the application message to.
msgProp Upon return from the method, this object will contain
the applied QOP, the privacy state, and supplementary
status values for the supplied token.
6.3.15. 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. This method is identical in
functionality to its stream counterpart.
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:
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inMsg Message to generate MIC over.
offset The offset within the inMsg where the token begins.
len The length of the token within the inMsg (starting at
the offset).
msgProp Indicates the desired QOP to be used. Use QOP of 0 to
indicate default value. The confidentiality flag is
ignored. Upon return from the method, this object will
contain the applied QOP (in case 0 was selected).
6.3.16. getMIC
public void getMIC(InputStream inMsg, OutputStream outBuf,
MessageProp msgProp) throws GSSException
Produces 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 produced in the output token. This method is identical in
functionality to its byte array counterpart.
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 Buffer containing the message to generate MIC over.
outBuf The buffer to write the GSS-API output token into.
msgProp Indicates the desired QOP to be used. Use QOP of 0 to
indicate default value. The confidentiality flag is
ignored. Upon return from the method, this object will
contain the applied QOP (in case 0 was selected).
6.3.17. verifyMIC
public void verifyMIC(byte []inTok, int tokOffset, int tokLen,
byte[] inMsg, int msgOffset, int msgLen,
MessageProp msgProp) throws GSSException
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Verifies the cryptographic MIC, contained in the token parameter,
over the supplied message. The msgProp parameter will contain the
QOP indicating the strength of protection that was applied to the
message. This method is equivalent in functionality to its stream
counterpart.
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 to verify the cryptographic MIC
over.
msgOffset The offset within the inMsg where the message begins.
msgLen The length of the message within the inMsg (starting
at the offset).
msgProp Upon return from the method, this object will contain
the applied QOP and supplementary status values for
the supplied token. The confidentiality state will be
always set to "false".
6.3.18. verifyMIC
public void verifyMIC(InputStream inTok, InputStream inMsg,
MessageProp msgProp) throws GSSException
Verifies the cryptographic MIC, contained in the token parameter,
over the supplied message. The msgProp parameter will contain the
QOP indicating the strength of protection that was applied to the
message. This method is equivalent in functionality to its byte array
counterpart.
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.
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Parameters:
inTok Contains the token generated by peer's getMIC method.
inMsg Contains application message to verify the
cryptographic MIC over.
msgProp Upon return from the method, this object will contain
the applied QOP and supplementary status values for
the supplied token. The confidentiality state will be
always set to "false".
6.3.19. 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
interprocess token which, when passed to the byte array constructor
of the GSSContext class 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
interprocess 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 interprocess token may contain security-sensitive information
(for example cryptographic keys). While mechanisms are encouraged to
either avoid placing such sensitive information within interprocess
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
interprocess token, and ensure that any process to which the token is
transferred is trustworthy.
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6.3.20. 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.
Parameters:
state Boolean representing if mutual authentication should
be requested during context establishment.
6.3.21. 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.
6.3.22. 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.
6.3.23. 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
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process begins and only for the initiator.
Parameter:
state Boolean representing if credential delegation is
desired.
6.3.24. 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.
Parameter:
state Boolean representing if anonymity support is
requested.
6.3.25. 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.
6.3.26. 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.
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6.3.27. 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.
Parameters:
lifetime The desired context lifetime in seconds.
6.3.28. 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.
6.3.29. 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.
6.3.30. 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.
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6.3.31. 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.
6.3.32. 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.
6.3.33. 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.
6.3.34. 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.
6.3.35. 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
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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.
6.3.36. 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.
6.3.37. 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.
6.3.38. 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.
6.3.39. 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".
6.3.40. getTargName
public GSSName getTargName() throws GSSException
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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".
6.3.41. getMech
public Oid getMech() throws GSSException
Returns the mechanism oid for this context.
6.3.42. 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.
6.3.43. 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.
6.4. 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 class 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.
When used with the unwrap and verifyMIC methods of the GSSContext
class, 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
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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.
6.4.1. Constructors
public MessageProp()
Default constructor for the class. QOP is set to 0 and
confidentiality to "false".
public MessageProp(int qop, boolean privState)
Constructor which sets the values for the qop and privacy state.
Parameters:
qop The desired QOP.
privState The desired privacy state.
6.4.2. getQOP
public int getQOP()
Retrieves the QOP value.
6.4.3. getPrivacy
public boolean getPrivacy()
Retrieves the privacy state.
6.4.4. setQOP
public void setQOP(int qopVal)
Sets the QOP value.
Parameter:
qopVal The QOP value to be set.
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6.4.5. setPrivacy
public void setPrivacy(boolean privState)
Sets the privacy state.
Parameter:
privState The privacy state to set.
6.4.6. isDuplicateToken
public boolean isDuplicateToken()
Returns "true" if this is a duplicate of an earlier token.
6.4.7. isOldToken
public boolean isOldToken()
Returns "true" if the token's validity period has expired.
6.4.8. isUnseqToken
public boolean isUnseqToken()
Returns "true" if a later token has already been processed.
6.4.9. isGapToken
public boolean isGapToken()
Returns "true" if an expected per-message token was not received.
6.5. public class GSSManager
This class implements functionality common to the entire GSS-API
package. It does not define any public constructors and all its
methods are static.
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6.5.1. getMechs
public static Oid[] getMechs()
Returns an array of Oid objects, one for each mechanism available
within this GSS-API package. A "null" value is returned when no
mechanism are available (an example of this would be when mechanism
are dynamically configured, and currently no mechanisms are
installed).
6.5.2. getNamesForMech
public static Oid[] getNamesForMech(Oid mech) throws GSSException
Returns name types Oids supported by the specified mechanism.
Parameters:
mech The Oid object for the mechanism to query.
6.5.3. getMechsForName
public static Oid[] getMechsForName(Oid nameType)
Returns an array of Oid objects, one for each 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 to query.
6.5.4. getDefaultMech
public static Oid getDefaultMech()
Returns the default mechanism oid. This is the mechanisms that will
be used when a "null" Oid object is specified in place of an Oid
object within GSSCredential and GSSContext methods.
6.6. public class ChannelBinding
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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.
6.6.1. 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 which the
application does not want to specify.
Parameters:
initAddr The address of the context initiator. "null" value
can be supplied to indicate that the application does
not want to set this value.
acceptAddrThe address of the context acceptor. "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. "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:
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appData Application supplied data to be used as part of the
channel bindings.
6.6.2. getInitiatorAddress
public InetAddress getInitiatorAddress()
Returns the initiator's address for this channel binding. "null" is
returned if the address has not been set.
6.6.3. getAcceptorAddress
public InetAddress getAcceptorAddress()
Returns the acceptor's address for this channel binding. "null" is
returned if the address has not been set.
6.6.4. 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.
6.6.5. equals
public boolean equals(Object obj)
Returns "true" if two channel bindings match.
Parameter:
obj Another channel binding to compare with.
6.7. public class Oid
This class represents Universal Object Identifiers (Oids) and their
associated operations.
Oids are hierarchically globally-interpretable identifiers used
within the GSS-API framework to identify mechanisms and name formats.
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The structure and encoding of Oids is defined in ISOIEC-8824 and
ISOIEC-8825. For example the Oid representation of 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.
6.7.1. 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 and ISOIEC-8825. This method is
identical in functionality to its byte array counterpart.
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 and ISOIEC-8825. This method is
identical in functionality to its byte array counterpart.
Parameters:
derOid Byte array storing a DER encoded oid.
6.7.2. toString
public String toString()
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Returns a string representation of the oid's integer components in
dot separated notation (e.g. "1.2.840.113554.1.2.2").
6.7.3. toRFC2078String
public String toRFC2078String()
Returns a string representation of the Oid's integer components in
the format specified within RFC 2078 (e.g. "{ 1 2 840 113554 1 2 2
}").
6.7.4. equals
public boolean equals(Object Obj)
Returns "true" if the two Oid objects represent the same oid value.
Parameter:
obj Another Oid object to compare with.
6.7.5. getDER
public byte[] getDER()
Returns the full ASN.1 DER encoding for this oid object, which
includes the tag and length.
6.7.6. containedIn
public boolean containedIn(Oid[] oids)
A utility method to test if an Oid object is contained within the
supplied Oid object array.
Parameter:
oids An array of oids to search.
6.8. public class GSSException extends Exception
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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 implementers 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. 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.
6.8.1. Class 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.
public static final int BAD_MECH
Unsupported mechanism requested error.
public static final int BAD_NAME
Invalid name provided error.
public static final int BAD_NAMETYPE
Name of unsupported type provided error.
public static final int BAD_STATUS
Invalid status code error - this is the default status value.
public static final int BAD_MIC
Token had invalid integrity check error.
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public static final int CONTEXT_EXPIRED
Specified security context expired error.
public static final int CREDENTIALS_EXPIRED
Expired credentials detected error.
public static final int DEFECTIVE_CREDENTIAL
Defective credential error.
public static final int DEFECTIVE_TOKEN
Defective token error.
public static final int FAILURE
General failure, unspecified at GSS-API level.
public static final int NO_CONTEXT
Invalid security context error.
public static final int NO_CRED
Invalid credentials error.
public static final int BAD_QOP
Unsupported QOP value error.
public static final int UNAUTHORIZED
Operation unauthorized error.
public static final int UNAVAILABLE
Operation unavailable error.
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public static final int DUPLICATE_ELEMENT
Duplicate credential element requested error.
public static final int NAME_NOT_MN
Name contains multi-mechanism elements error.
public static final int DUPLICATE_TOKEN
The token was a duplicate of an earlier token. This is a fatal error
code that may occur during context establishment. It is not used to
indicate supplementary status values. The MessageProp object is used
for that purpose.
public static final int OLD_TOKEN
The token's validity period has expired. This is a fatal error code
that may occur during context establishment. It is not used to
indicate supplementary status values. The MessageProp object is used
for that purpose.
public static final int UNSEQ_TOKEN
A later token has already been processed. This is a fatal error code
that may occur during context establishment. It is not used to
indicate supplementary status values. The MessageProp object is used
for that purpose.
public static final int GAP_TOKEN
An expected per-message token was not received. This is a fatal
error code that may occur during context establishment. It is not
used to indicate supplementary status values. The MessageProp object
is used for that purpose.
6.8.2. Constructors
public GSSException(int majorCode)
Creates a GSSException object with a specified major code.
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Parameters:
majorCode The GSS error code causing this exception to be
thrown.
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.
Parameters:
majorCode The GSS error code causing this exception to be
thrown.
minorCode The mechanism error code causing this exception
to be thrown.
minorString The textual explanation of the mechanism error
code.
6.8.3. getMajor
public int getMajor()
Returns the major code representing the GSS error code that caused
this exception to be thrown.
6.8.4. getMinor
public int getMinor()
Returns the mechanism error code that caused this exception. The
minor code is set by the underlying mechanism. Value of 0 indicates
that mechanism error code is not set.
6.8.5. getMajorString
public String getMajorString()
Returns a string explaining the GSS major error code causing this
exception to be thrown.
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6.8.6. getMinorString
public String getMinorString()
Returns a string explaining the mechanism specific error code. An
empty string will be returned when no mechanism error code has been
set.
6.8.7. 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.
6.8.8. toString
public String toString()
Returns a textual representation of both the major and minor status
codes.
6.8.9. 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.
7. Acknowledgments
This proposed API leverages earlier work performed by the IETF's CAT
WG as outlined in both RFC 2078 and J. Wray's C-bindings draft for
the GSS-API. Many conceptual definitions, implementation directions,
and explanations have been included from the C-bindings draft.
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I would like to thank Mike Eisler, Mayank Upadhyay, Lin Ling, Ram
Marti, Michael Saltz and other members of Sun's development team for
their helpful input, comments and suggestions.
I would also like to thank Michael Smith for many insightful ideas
and suggestions that have contributed to this draft.
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8. Bibliography
[GSSAPIv2]
J. Linn, "Generic Security Service Application Program Interface,
Version 2", RFC 2078, January 1997.
[GSSAPIv2-UPDATE]
J. Linn, "Generic Security Service Application Program Interface,
Version 2, Update 1", IETF work in progress, Internet Draft, July
1998.
[GSSAPI-Cbind]
J. Wray, "Generic Security Service API Version 2 : C-bindings", IETF
work in progress, Internet Draft, July 1998.
[KERBEROS_V5]
J. Linn, "The Kerberos Version 5 GSS-API Mechanism", RFC 1964, June
1996.
[SPKM]
C. Adams, "The Simple Public-Key GSS-API Mechanism", RFC 2025,
October 1996.
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9. Author's Address
Address comments related to this memorandum to:
<cat-ietf@mit.edu>
Jack Kabat
ValiCert, Inc.
1215 Terra Bella Avenue
Mountain View, CA
94043, USA
Phone: +1-650-567-5496
E-mail: jackk@valicert.com
Mayank Upadhyay
Sun Microsystems, Inc.
901 San Antonio Road, MS MPK17-201
Palo Alto, CA 94303
Phone: +1-650-786-4282
E-mail: mdu@eng.sun.com
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