/* GSSContext.java -- The GSS context interface.
   Copyright (C) 2004 Free Software Foundation, Inc.

This file is part of GNU Classpath.

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permission to link this library with independent modules to produce an
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package org.ietf.jgss;

import java.io.InputStream;
import java.io.OutputStream;

/**
 * <p>This interface encapsulates the GSS-API security context and provides
 * the security services ({@link #wrap(byte[],int,int,org.ietf.jgss.MessageProp)},
 * {@link #unwrap(byte[],int,int,org.ietf.jgss.MessageProp)}, {@link
 * #getMIC(byte[],int,int,org.ietf.jgss.MessageProp)}, {@link
 * #verifyMIC(byte[],int,int,byte[],int,int,org.ietf.jgss.MessageProp)}) that
 * are available over the context.  Security contexts are established
 * between peers using locally acquired credentials.  Multiple contexts
 * may exist simultaneously between a pair of peers, using the same or
 * 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.</p>
 *
 * <p>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.</p>
 *
 * <p>The context establishment phase begins with the first call to the
 * init method by the context initiator.  During this phase the
 * {@link #initSecContext(byte[],int,int)} and {@link
 * #acceptSecContext(byte[],int,int)} methods will produce GSS-API
 * authentication tokens which the calling application needs to send to
 * its peer.  If an error occurs at any point, an exception will get
 * thrown and the code will start executing in a catch block.  If not,
 * the normal flow of code continues and the application can make a call
 * to the {@link #isEstablished()} method. If this method returns false it
 * indicates that a token is needed from its peer in order to continue
 * the context establishment phase.  A return value of true signals that
 * the local end of the context is established.  This may still require
 * that a token be sent to the peer, if one is produced by GSS-API.
 * During the context establishment phase, the {@link #isProtReady()}
 * method may be called to determine if the context can be used for the
 * per-message operations.  This allows applications to use per-message
 * operations on contexts which aren't fully established.</p>
 *
 * <p>After the context has been established or the {@link #isProtReady()}
 * method returns <code>true</code>, 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 {@link #wrap(byte[],int,int,org.ietf.jgss.MessageProp)} and
 * {@link #getMIC(byte[],int,int,org.ietf.jgss.MessageProp)} to obtain
 * cryptographic operations on application supplied data.</p>
 *
 * <p>When the context is no longer needed, the application should call
 * {@link dispose()} to release any system resources the context may be
 * using.</p>
 *
 * <h3>Example Code</h3>
 *
 * <pre>
GSSManager mgr = GSSManager.getInstance();

// start by creating the name for a service entity
GSSName targetName = mgr.createName("service@host",
                                    GSSName.NT_HOSTBASED_SERVICE);

// create a context using default credentials for the above entity
// and the implementation specific default mechanism
GSSContext context = mgr.createContext(targetName,
                                       null,   // default mechanism
                                       null,   // default credentials
                                       GSSContext.INDEFINITE_LIFETIME);

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

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

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

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

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

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

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

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

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

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

// perform wrap on an application supplied message, appMsg,
// using QOP = 0, and requesting privacy service
byte[] appMsg ...
MessageProp mProp = new MessageProp(0, true);
byte[] tok = context.wrap(appMsg, 0, appMsg.length, mProp);

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

sendToken(tok);


// release the local-end of the context
context.dispose();
 * </pre>
 */
public interface GSSContext
{

  // Constants.
  // -------------------------------------------------------------------------

  /**
   * A lifetime constant representing the default context lifetime.
   */
  int DEFAULT_LIFETIME = 0;

  /**
   * A lifetime constant representing indefinite context lifetime.
   */
  int INDEFINITE_LIFETIME = Integer.MAX_VALUE;

  // Methods.
  // -------------------------------------------------------------------------

  /**
   * <p>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.  Typically, the application would do so by calling the
   * {@link OutputStream#flush()} method on an OutputStream that
   * encapsulates the connection between the two peers.  The application
   * can call {@link #isEstablished()} to determine if the context
   * establishment phase is complete for this peer.  A return value of
   * <code>false</code> from {@link #isEstablished()} indicates that more
   * tokens are expected to be supplied to the initSecContext() method. Note
   * that it is possible that the initSecContext() method return a token for
   * the peer, and {@link #isEstablished()} to return <code>true</code> also.
   * This indicates that the token needs to be sent to the peer, but the local
   * end of the context is now fully established.</p>
   *
   * <p>Upon completion of the context establishment, the available context
   * options may be queried through the get methods.</p>
   *
   * @param inputBuf Token generated by the peer. This parameter is ignored
   *                 on the first call.
   * @param offset   The offset within the <i>inputBuf</i> where the token
   *                 begins.
   * @param len      The length of the token within the <i>inputBuf</i>
   *                 (starting at the offset).
   * @return The output token, if any.
   * @throws GSSException If this operation fails.
   */
  byte[] initSecContext(byte[] inputBuf, int offset, int len)
    throws GSSException;

  /**
   * <p>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 <i>outStream</i>, which the
   * application will need to send to the peer for processing by the
   * accept call. Typically, the application would do so by calling the
   * {@link OutputStream#flush()} method on an OutputStream that encapsulates
   * the connection between the two peers. The application can call {@link
   * #isEstablished()} to determine if the context establishment phase is
   * complete for this peer. A return value of <code>false</code> from
   * isEstablished indicates that more tokens are expected to be supplied
   * to the initSecContext() method. Note that it is possible that the
   * initSecContext() method return a token for the peer, and {@link
   * #isEstablished() return <code>true</code> also. This indicates that
   * the token needs to be sent to the peer, but the local end of the context
   * is now fully established.</p>
   *
   * <p>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.</p>
   *
   * <p>Upon completion of the context establishment, the available context
   * options may be queried through the get methods.</p>
   *
   * @param inStream  Contains the token generated by the peer. This
   *                  parameter is ignored on the first call.
   * @param outStream Output stream where the output token will be written.
   *                  During the final stage of context establishment, there
   *                  may be no bytes written.
   * @return The number of bytes written to <i>outStream</i>, or 0 if no
   *         token is written.
   * @throws GSSException If this operation fails.
   */
  int initSecContext(InputStream inStream, OutputStream outStream)
    throws GSSException;

  /**
   * <p>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.</p>
   *
   * <p>This method may return an output token which the application will
   * need to send to the peer for further processing by the init call.</p>
   *
   * <p><code>null</code> return value indicates that no token needs to be
   * sent to the peer. The application can call {@link #isEstablished()}
   * to determine if the context establishment phase is complete for this
   * peer. A return value of <code>false</code> from {@link #isEstablished()}
   * indicates that more tokens are expected to be supplied to this
   * method.</p>
   *
   * <p>Note that it is possible that acceptSecContext() return a token for
   * the peer, and isEstablished() return <code>true</code> also. This
   * indicates that the token needs to be sent to the peer, but the local
   * end of the context is now fully established.</p>
   *
   * <p>Upon completion of the context establishment, the available context
   * options may be queried through the get methods.</p>
   *
   * @param inTok  Token generated by the peer.
   * @param offset The offset within the <i>inTok</i> where the token begins.
   * @param len    The length of the token within the <i>inTok</i> (starting
   *               at the offset).
   * @return The output token, if any.
   * @throws GSSException If this operation fails.
   */
  byte[] acceptSecContext(byte[] inTok, int offset, int len)
    throws GSSException;

  /**
   * <p>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 outStream, which the application will need to
   * send to the peer for processing by its initSecContext method.
   * Typically, the application would do so by calling the {@link
   * OutputStream#flush()} method on an OutputStream that encapsulates the
   * connection between the two peers. The application can call {@link
   * #isEstablished()} to determine if the context establishment phase is
   * complete for this peer. A return value of <code>false</code> from
   * {@link #isEstablished()} indicates that more tokens are expected to be
   * supplied to this method.</p>
   *
   * <p>Note that it is possible that acceptSecContext() return a token for
   * the peer, and isEstablished() return <code>true</code> also. This
   * indicates that the token needs to be sent to the peer, but the local
   * end of the context is now fully established.</p>
   *
   * <p>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.</p>
   *
   * <p>Upon completion of the context establishment, the available context
   * options may be queried through the get methods.</p>
   *
   * @param inStream  Contains the token generated by the peer.
   * @param outStream Output stream where the output token will be written.
   *                  During the final stage of context establishment, there
   *                  may be no bytes written.
   * @return The number of bytes written, or 0 if no token is written.
   * @throws GSSException If this operation fails.
   */
  void acceptSecContext(InputStream inStream, OutputStream outStream)
    throws GSSException;

  /**
   * Used during context establishment to determine the state of the
   * context. Returns <code>true</code> if this is a fully established
   * context on the caller's side and no more tokens are needed from the
   * peer. Should be called after a call to {@link
   * #initSecContext(byte[],int,int)} or {@link
   * #acceptSecContext(byte[],int,int)} when no {@link GSSException}
   * is thrown.
   *
   * @return True of this context is fully established on this side.
   */
  boolean isEstablished();

  /**
   * Releases any system resources and cryptographic information stored in
   * the context object. This will invalidate the context.
   *
   * @throws GSSException If this operation fails.
   */
  void dispose() throws GSSException;

  /**
   * <p>Returns the maximum message size that, if presented to the
   * {@link #wrap(byte[],int,int,org.ietf.jgss.MessageProp)} method with
   * the same <i>confReq</i> and <i>qop</i> parameters, will result in an
   * output token containing no more than the <i>maxTokenSize</i> bytes.</p>
   *
   * <p>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.</p>
   *
   * <p>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.</p>
   *
   * <p>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.</p>
   *
   * @param qop          Indicates the level of protection wrap will be asked
   *                     to provide.
   * @param confReq      Indicates if wrap will be asked to provide privacy
   *                     service.
   * @param maxTokenSize The desired maximum size of the token emitted
   *                     by {@link #wrap(byte[],int,int,org.ietf.jgss.MessageProp)}.
   * @return The maximum wrapped output size.
   * @throws GSSException If this operation fails.
   */
  int getWrapSizeLimit(int qop, boolean confReq, int maxTokenSize)
    throws GSSException;

  /**
   * <p>Applies per-message security services over the established security
   * context.  The method will return a token with a cryptographic MIC and
   * may optionally encrypt the specified <i>inBuf</i>. This method is
   * equivalent in functionality to its stream counterpart. The returned
   * byte array will contain both the MIC and the message.</p>
   *
   * <p>The {@link MessageProp} object is instantiated by the application
   * and used to specify a QOP value which selects cryptographic algorithms,
   * and a privacy service to optionally encrypt the message. The underlying
   * mechanism that is used in the call may not be able to provide the
   * privacy service.  It sets the actual privacy service that it does
   * provide in this {@link MessageProp} object which the caller should then
   * query upon return. If the mechanism is not able to provide the
   * requested QOP, it throws a {@link GSSException} with the {@link
   * GSSException#BAD_QOP} code.</p>
   *
   * <p>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.</p>
   *
   * <p>The application will be responsible for sending the token to the
   * peer.</p>
   *
   * @param inBuf   Application data to be protected.
   * @param offset  The offset within the inBuf where the data begins.
   * @param len     The length of the data within the inBuf (starting at
   *                the offset).
   * @param msgProp Instance of {@link MessageProp} that is used by the
   *                application to set the desired QOP and privacy state.
   *                Set the desired QOP to 0 to request the default QOP.
   *                Upon return from this method, this object will contain
   *                the the actual privacy state that was applied to the
   *                message by the underlying mechanism.
   * @return The wrapped data.
   * @throws GSSException If this operation fails.
   */
  byte[] wrap(byte[] inBuf, int offset, int len, MessageProp msgProp)
    throws GSSException;

  /**
   * <p>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 message in inStream.
   * The outStream will contain both the MIC and the message.</p>
   *
   * <p>The {@link MessageProp} object is instantiated by the application and
   * used to specify a QOP value which selects cryptographic algorithms, and
   * a privacy service to optionally encrypt the message.  The underlying
   * mechanism that is used in the call may not be able to provide the
   * privacy service.  It sets the actual privacy service that it does
   * provide in this MessageProp object which the caller should then query
   * upon return.  If the mechanism is not able to provide the requested
   * QOP, it throws a {@link GSSException} with the {@link
   * GSSException#BAD_QOP} code.</p>
   *
   * <p>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.</p>
   *
   * <p>The application will be responsible for sending the token to the
   * peer.</p>
   *
   * @param inStream  Input stream containing the application data to be
   *                  protected.
   * @param outStream The output stream to write the protected message to.
   *                  The application is responsible for sending this to the
   *                  other peer for processing in its unwrap method.
   * @param msgProp   Instance of {@link MessageProp} that is used by the
   *                  application to set the desired QOP and privacy state.
   *                  Set the desired QOP to 0 to request the default QOP.
   *                  Upon return from this method, this object will contain
   *                  the the actual privacy state that was applied to the
   *                  message by the underlying mechanism.
   * @throws GSSException If this operation fails.
   */
  void wrap(InputStream inStream, OutputStream outStream, MessageProp msgProp)
    throws GSSException;

  /**
   * <p>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.</p>
   *
   * <p>The {@link MessageProp} object is instantiated by the application and
   * is used by the underlying mechanism to return information to the caller
   * such as the QOP, whether confidentiality was applied to the message, and
   * other supplementary message state information.</p>
   *
   * <p>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.</p>
   *
   * @param inBuf   GSS-API wrap token received from peer.
   * @param offset  The offset within the inBuf where the token begins.
   * @param len     The length of the token within the inBuf (starting at
   *                the offset).
   * @param msgProp Upon return from the method, this object will contain
   *                the applied QOP, the privacy state of the message, and
   *                supplementary information stating whether the token was
   *                a duplicate, old, out of sequence or arriving after a gap.
   * @return The unwrapped token.
   * @throws GSSException If this operation fails.
   */
  byte[] unwrap(byte[] inBuf, int offset, int len, MessageProp msgProp)
    throws GSSException;

  /**
   * <p>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.</p>
   *
   * <p>The {@link MessageProp} object is instantiated by the application
   * and is used by the underlying mechanism to return information to the
   * caller such as the QOP, whether confidentiality was applied to the
   * message, and other supplementary message state information.</p>
   *
   * <p>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.</p>
   *
   * @param inStream  Input stream containing the GSS-API wrap token
   *                  received from the peer.
   * @param outStream The output stream to write the application message to.
   * @param msgProp   Upon return from the method, this object will contain
   *                  the applied QOP, the privacy state of the message, and
   *                  supplementary information stating whether the token was
   *                  a duplicate, old, out of sequence or arriving after a gap.
   * @throws GSSException If this operation fails.
   */
  void unwrap(InputStream inStream, OutputStream outStream, MessageProp msgProp)
    throws GSSException;

  /**
   * <p>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.</p>
   *
   * <p>Note that privacy can only be applied through the wrap call.</p>
   *
   * <p>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.</p>
   *
   * @param inMsg   Message to generate MIC over.
   * @param offset  The offset within the inMsg where the token begins.
   * @param len     The length of the token within the inMsg (starting at
   *                the offset).
   * @param msgProp Instance of MessageProp that is used by the
   *                application to set the desired QOP.  Set the desired
   *                QOP to 0 in msgProp to request the default QOP.
   *                Alternatively pass in <code>null</code> for msgProp to
   *                request default QOP.
   * @return The MIC.
   * @throws GSSException If this operation fails.
   */
  byte[] getMIC(byte[] inMsg, int offset, int len, MessageProp msgProp)
    throws GSSException;

  /**
   * <p>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.</p>
   *
   * <p>Note that privacy can only be applied through the wrap call.</p>
   *
   * <p>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.</p>
   *
   * @param inStream  Input stream containing the message to generate
   *                  the MIC over.
   * @param outStream Output stream to write the GSS-API output token to.
   * @param msgProp   Instance of MessageProp that is used by the
   *                  application to set the desired QOP.  Set the desired
   *                  QOP to 0 in msgProp to request the default QOP.
   *                  Alternatively pass in <code>null</code> for msgProp
   *                  to request default QOP.
   * @throws GSSException If this operation fails.
   */
  void getMIC(InputStream inStream, OutputStream outStream, MessageProp mgProp)
    throws GSSException;

  /**
   * <p>Verifies the cryptographic MIC, contained in the token parameter,
   * over the supplied message.  This method is equivalent in
   * functionality to its stream counterpart.</p>
   *
   * <p>The MessageProp object is instantiated by the application and is used
   * by the underlying mechanism to return information to the caller such
   * as the QOP indicating the strength of protection that was applied to
   * the message and other supplementary message state information.</p>
   *
   * <p>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.</p>
   *
   * @param inTok     Token generated by peer's getMIC method.
   * @param tokOffset The offset within the inTok where the token begins.
   * @param tokLen    The length of the token within the inTok (starting at
   *                  the offset).
   * @param inMsg     Application message to verify the cryptographic MIC
   *                  over.
   * @param msgOffset The offset within the inMsg where the message begins.
   * @param msgLen    The length of the message within the inMsg (starting
   *                  at the offset).
   * @param msgProp   Upon return from the method, this object will contain
   *                  the applied QOP and supplementary information
   *                  stating whether the token was a duplicate, old, out
   *                  of sequence or arriving after a gap.  The
   *                  confidentiality state will be set to <code>false</code>.
   * @throws GSSException If this operation fails.
   */
  void verifyMIC(byte[] inTok, int tokOffset, int tokLen, byte[] inMsg,
                 int msgOffset, int msgLen, MessageProp msgProp)
    throws GSSException;

  /**
   * <p>Verifies the cryptographic MIC, contained in the token parameter,
   * over the supplied message.  This method is equivalent in
   * functionality to its byte array counterpart.</p>
   *
   * <p>The MessageProp object is instantiated by the application and is used
   * by the underlying mechanism to return information to the caller such
   * as the QOP indicating the strength of protection that was applied to
   * the message and other supplementary message state information.</p>
   *
   * <p>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.</p>
   *
   * @param tokStream Input stream containing the token generated by peer's
   *                  getMIC method.
   * @param msgStream Input stream containing the application message to
   *                  verify the cryptographic MIC over.
   * @param msgProp   Upon return from the method, this object will contain
   *                  the applied QOP and supplementary information
   *                  stating whether the token was a duplicate, old, out of
   *                  sequence or arriving after a gap.  The confidentiality
   *                  state will be set to <code>false</code>.
   * @throws GSSException If this operation fails.
   */
  void verifyMIC(InputStream tokStream, InputStream msgStream, MessageProp msgProp)
    throws GSSException;

  /**
   * <p>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.</p>
   *
   * <p>This method deactivates the security context and creates an
   * interprocess token which, when passed to the byte array constructor
   * of the GSSContext interface in another process, will re-activate the
   * context in the second process.  Only a single instantiation of a
   * given context may be active at any one time; a subsequent attempt by
   * a context exporter to access the exported security context will fail.</p>
   *
   * <p>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.</p>
   *
   * <p>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.</p>
   *
   * @return The exported context.
   * @throws GSSException If this operation fails.
   */
  byte[] export() throws GSSException;

  /**
   * <p>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.</p>
   *
   * @param state Boolean representing if mutual authentication should
   *              be requested during context establishment.
   * @throws GSSException If this operation fails.
   */
  void requestMutualAuth(boolean state) throws GSSException;

  /**
   * <p>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.</p>
   *
   * @param state Boolean representing if replay detection is desired
   *              over the established context.
   * @throws GSSException If this operation fails.
   */
  void requestReplayDet(boolean state) throws GSSException;

  /**
   * <p>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.</p>
   *
   * @param state Boolean representing if sequence detection is desired
   *              over the established context.
   * @throws GSSException If this operation fails.
   */
  void requestSequenceDet(boolean state) throws GSSException;

  /**
   * <p>Sets the request state for the credential delegation flag for the
   * context.  This method is only valid before the context creation
   * process begins and only for the initiator.</p>
   *
   * @param state Boolean representing if credential delegation is
   *              desired.
   * @throws GSSException If this operation fails.
   */
  void requestCredDeleg(boolean state) throws GSSException;

  /**
   * <p>Requests anonymous support over the context.  This method is only
   * valid before the context creation process begins and only for the
   * initiator.</p>
   *
   * @param state Boolean representing if anonymity support is requested.
   * @throws GSSException If this operation fails.
   */
  void requestAnonymity(boolean state) throws GSSException;

  /**
   * <p>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.</p>
   *
   * @param state Boolean indicating if confidentiality services are to
   *              be requested for the context.
   * @throws GSSException If this operation fails.
   */
  void requestConf(boolean state) throws GSSException;

  /**
   * <p>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.</p>
   *
   * @param state Boolean indicating if integrity services are to be
   *              requested for the context.
   * @throws GSSException If this operation fails.
   */
  void requestInteg(boolean state) throws GSSException;

  /**
   * <p>Sets the desired lifetime for the context in seconds. This method is
   * only valid before the context creation process begins and only for
   * the initiator. Use {@link #INDEFINITE_LIFETIME} and {@link
   * #DEFAULT_LIFETIME} to request indefinite or default context lifetime.</p>
   *
   * @param lifetime The desired context lifetime in seconds.
   * @throws GSSException If this operation fails.
   */
  void requestLifetime(int lifetime) throws GSSException;

  /**
   * <p>Sets the channel bindings to be used during context establishment.
   * This method is only valid before the context creation process begins.</p>
   *
   * @param cb Channel bindings to be used.
   * @throws GSSException If this operation fails.
   */
  void setChannelBinding(ChannelBinding cb) throws GSSException;

  /**
   * <p>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.</p>
   *
   * @return The state of the delegated credentials for the context.
   */
  boolean getCredDelegState();

  /**
   * <p>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.</p>
   *
   * @return The state of the mutual authentication option.
   */
  boolean getMutualAuthState();

  /**
   * <p>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.</p>
   *
   * @return The state of the replay detection option.
   */
  boolean getReplayDetState();

  /**
   * <p>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.</p>
   *
   * @return The state of the sequence detection option.
   */
  boolean getSequenceDetState();

  /**
   * <p>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.</p>
   *
   * @return True if this is an anonymous context.
   */
  boolean getAnonymityState();

  /**
   * <p>Returns "true" if the context is transferable to other processes
   * through the use of the {@link #export()} method. This call is only
   * valid on fully established contexts.</p>
   *
   * @return True if the context is transferable.
   * @throws GSSException If this operation fails.
   */
  boolean isTransferable() throws GSSException;

  /**
   * <p>Returns "true" if the per message operations can be applied over
   * the context.  Some mechanisms may allow the usage of per-message
   * operations before the context is fully established.  This will also
   * indicate that the get methods will return actual context state
   * characteristics instead of the desired ones.</p>
   *
   * @return True if the per message operations can be applied over
   *         the context.
   */
  boolean isProtReady();

  /**
   * <p>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.</p>
   *
   * @return True the confidentiality service state.
   */
  boolean getConfState();

  /**
   * <p>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.</p>
   *
   * @return The integrity service state.
   */
  boolean getIntegState();

  /**
   * <p>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.</p>
   *
   * @return The lifetime.
   */
  int getLifetime();

  /**
   * <p>Returns the name of the context initiator. This call is valid only
   * after the context is fully established or the isProtReady method
   * returns "true".  It is guaranteed to return an MN.</p>
   *
   * @return The name of the context initiator.
   * @throws GSSException If this operation fails.
   */
  GSSName getSrcName() throws GSSException;

  /**
   * <p>Returns the name of the context target (acceptor).  This call is
   * valid only after the context is fully established or the isProtReady
   * method returns "true".  It is guaranteed to return an MN.</p>
   *
   * @return The name of the context target.
   * @throws GSSException If this operation fails.
   */
  GSSName getTargName() throws GSSException;

  /**
   * <p>Returns the mechanism oid for this context. This method may be called
   * before the context is fully established, but the mechanism returned
   * may change on successive calls in negotiated mechanism case.</p>
   *
   * @return The mechanism OID.
   * @throws GSSException If this operation fails.
   */
  Oid getMech() throws GSSException;

  /**
   * <p>Returns the delegated credential object on the acceptor's side.
   * To check for availability of delegated credentials call
   * {@link #getDelegCredState()}. This call is only valid on fully
   * established contexts.</p>
   *
   * @return The delegated credential object.
   * @throws GSSException If this operation fails.
   */
  GSSCredential getDelegCred() throws GSSException;

  /**
   * <p>Returns "true" if this is the initiator of the context. This call is
   * only valid after the context creation process has started.</p>
   *
   * @return True if this is the initiator.
   * @throws GSSException If this operation fails.
   */
  boolean isInitiator() throws GSSException;
}