7.  Detailed GSS-API Class Description

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

7.1.  public abstract class GSSManager

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

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

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

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

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

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

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

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

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

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

7.1.1.  Example Code

      GSSManager mgr = GSSManager.getInstance();

      // What mechs are available to us?

      Oid[] supportedMechs = mgr.getMechs();

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

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

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

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

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

7.1.2.  getInstance

   public static GSSManager getInstance()

   Returns the default GSSManager implementation.

7.1.3.  getMechs

   public abstract Oid[] getMechs()

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

7.1.4.  getNamesForMech

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

   Returns name type Oid's supported by the specified mechanism.

   Parameters:

      mech:         The Oid object for the mechanism to query.

7.1.5.  getMechsForName

   public abstract Oid[] getMechsForName(Oid nameType)

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

   Parameters:

      nameType:     The Oid object for the name type.

7.1.6.  createName

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

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

   Parameters:

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

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

7.1.7.  createName

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

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

   Parameters:

      name:         The byte array containing the name to create.

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

7.1.8.  createName

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

   Factory method to convert a contiguous string name from the specified
   namespace to a GSSName object that is a mechanism name (MN).  In
   other words, this method is a utility that does the equivalent of two
   steps: the createName described in section 7.1.6, and then also the
   GSSName.canonicalize() described in section 7.2.5.

   Parameters:

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

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

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

7.1.9.  createName

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

   Factory method to convert a contiguous byte array containing a name
   from the specified namespace to a GSSName object that is an MN.  In
   other words, this method is a utility that does the equivalent of two
   steps: the createName described in section 7.1.7, and then also the
   GSSName.canonicalize() described in section 7.2.5.

   Parameters:

      name:         The byte array representing the name to create.

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

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

7.1.10.  createCredential

   public abstract GSSCredential createCredential(int usage)
                   throws GSSException

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

   Parameters:

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

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

7.1.11.  createCredential

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

   Factory method for acquiring a single mechanism credential.

   Parameters:

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

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

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

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

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

7.1.12.  createCredential

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

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

   Parameters:

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

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

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

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

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

7.1.13.  createContext

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

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

   Parameters:

      peer:         Name of the target peer.

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

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

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

7.1.14.  createContext

   public abstract GSSContext createContext(GSSCredential myCred)
                   throws GSSException

   Factory method 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.

7.1.15.  createContext

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

   Factory method 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.

7.1.16.  addProviderAtFront

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

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

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

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

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

   Parameters:

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

      mech:         The mechanism for which the provider is being set.

7.1.17.  Example Code

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

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

      mgr.addProviderAtFront(A, null);

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

      mgr.addProviderAtFront(B, m1);

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

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

      mgr.addProviderAtFront(B, null)

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

   Please note, however, that the following call:

      mgr.addProviderAtFront(A, m3)

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

7.1.18.  addProviderAtEnd

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

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

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

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

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

   Parameters:

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

      mech:         The mechanism for which the provider is being set.

7.1.19.  Example Code

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

      GSSManager mgr = GSSManager.getInstance();

      mgr.addProviderAtEnd(A, m1);

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

      mgr.addProviderAtEnd(B, null);

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

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

      mgr.addProviderAtEnd(B, m2)

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

   Please note, however, that the following call:

      mgr.addProviderAtEnd(A, null)

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

7.2.  public interface GSSName

   This interface 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 its namespace type.

7.2.1.  Example Code

   Included below are code examples utilizing the GSSName interface.
   The code below creates a GSSName, 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.

      GSSManager mgr = GSSManager.getInstance();

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

      Oid krb5 = new Oid("1.2.840.113554.1.2.2");

      GSSName mechName = name.canonicalize(krb5);

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

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

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

      // export and re-import the name
      byte[] exportName = mechName.export();

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

7.2.2.  Static Constants

   public static final Oid NT_HOSTBASED_SERVICE

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

      service@hostname

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

   public static final Oid NT_USER_NAME

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

   public static final Oid NT_MACHINE_UID_NAME

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

   public static final Oid NT_STRING_UID_NAME

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

   public static final Oid NT_ANONYMOUS

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

   public static final Oid NT_EXPORT_NAME

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

7.2.3.  equals

   public boolean equals(GSSName another) throws GSSException

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

   Parameters:

      another:      GSSName object with which to compare.

7.2.4.  equals

      public boolean equals(Object another)

      A variation of the equals method, described in section 7.2.3, that
      is provided to override the Object.equals() method that the
      implementing class will inherit.  The behavior is exactly the same
      as that in section 7.2.3 except that no GSSException is thrown;
      instead, "false" will be returned in the situation where an error
      occurs.  (Note that the Java language specification requires that
      two objects that are equal according to the equals(Object) method
      must return the same integer result when the hashCode() method is
      called on them.)

      Parameters:

      another:      GSSName object with which to compare.

7.2.5.  canonicalize

      public GSSName canonicalize(Oid mech) throws GSSException

      Creates a mechanism name (MN) from an arbitrary internal name.
      This is equivalent to using the factory methods described in
      sections 7.1.8 or 7.1.9 that take the mechanism name as one of
      their parameters.

      Parameters:

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

7.2.6.  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.  If the name is not an MN, implementations
   may throw a GSSException with the NAME_NOT_MN status code.  If an
   implementation chooses not to throw an exception, it should use some
   system-specific default mechanism to canonicalize the name and then
   export it.  The format of the header of the output buffer is
   specified in RFC 2743 [GSSAPIv2-UPDATE].

7.2.7.  toString

   public String toString()

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

7.2.8.  getStringNameType

   public Oid getStringNameType() throws GSSException

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

7.2.9.  isAnonymous

   public boolean isAnonymous()

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

7.2.10.  isMN

   public boolean isMN()

   Tests if this name object contains only one mechanism element and is
   thus a mechanism name as defined by RFC 2743 [GSSAPIv2-UPDATE].

7.3.  public interface GSSCredential implements Cloneable

   This interface encapsulates the GSS-API credentials for an entity.  A
   credential contains all the necessary cryptographic information to
   enable the creation of a context on behalf of the entity that it

   represents.  It may contain multiple, distinct, mechanism-specific
   credential elements, each containing information for a specific
   security mechanism, but all referring to the same entity.

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

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

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

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

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

7.3.1.  Example Code

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

      GSSManager mgr = GSSManager.getInstance();

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

      // now acquire credentials for the entity
      GSSCredential cred = mgr.createCredential(name,
                           GSSCredential.ACCEPT_ONLY);

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

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

7.3.2.  Static Constants

   public static final int INITIATE_AND_ACCEPT

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

   public static final int INITIATE_ONLY

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

   public static final int ACCEPT_ONLY

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

   public static final int DEFAULT_LIFETIME

   A lifetime constant representing the default credential lifetime.

   The value of this constant is 0.

   public static final int INDEFINITE_LIFETIME

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

7.3.3.  dispose

   public void dispose() throws GSSException

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

7.3.4.  getName

   public GSSName getName() throws GSSException

   Retrieves the name of the entity that the credential asserts.

7.3.5.  getName

   public GSSName getName(Oid mechOID) throws GSSException

   Retrieves a mechanism name of the entity that the credential asserts.
   Equivalent to calling canonicalize() on the name returned by section
   7.3.4.

   Parameters:

      mechOID:      The mechanism for which information should be
                    returned.

7.3.6.  getRemainingLifetime

   public int getRemainingLifetime() throws GSSException

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

7.3.7.  getRemainingInitLifetime

   public int getRemainingInitLifetime(Oid mech) throws GSSException

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

   Parameters:

      mechOID:      The mechanism for which information should be
                    returned.

7.3.8.  getRemainingAcceptLifetime

   public int getRemainingAcceptLifetime(Oid mech) throws GSSException

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

   Parameters:

      mechOID:      The mechanism for which information should be
                    returned.

7.3.9.  getUsage

   public int getUsage() throws GSSException

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

7.3.10.  getUsage

   public int getUsage(Oid mechOID) throws GSSException

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

   Parameters:

      mechOID:      The mechanism for which information should be
                    returned.

7.3.11.  getMechs

   public Oid[] getMechs() throws GSSException

   Returns an array of mechanisms supported by this credential.

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

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

   Parameters:

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

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

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

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

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

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

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

7.3.13.  equals

   public boolean equals(Object another)

   Tests if this GSSCredential refers to the same entity as the supplied
   object.  The two credentials must be acquired over the same
   mechanisms and must refer to the same principal.  Returns "true" if
   the two GSSCredentials refer to the same entity; "false" otherwise.
   (Note that the Java language specification [JLS] requires that two
   objects that are equal according to the equals(Object) method must
   return the same integer result when the hashCode() method is called
   on them.)

   Parameters:

      another:      Another GSSCredential object for comparison.