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package sun.security.jgss.krb5;

import org.ietf.jgss.*;
import sun.security.jgss.*;
import java.io.InputStream;
import java.io.OutputStream;
import java.io.IOException;
import java.io.ByteArrayInputStream;
import java.security.MessageDigest;

This class is a base class for other token definitions that pertain to
per-message GSS-API calls. Conceptually GSS-API has two types of
per-message tokens: WrapToken and MicToken. They differ in the respect
that a WrapToken carries additional plaintext or ciphertext application
data besides just the sequence number and checksum. This class
encapsulates the commonality in the structure of the WrapToken and the
MicToken. This structure can be represented as:

    0..1           TOK_ID          Identification field.
                                   01 01 - Mic token
                                   02 01 - Wrap token
    2..3           SGN_ALG         Checksum algorithm indicator.
                                   00 00 - DES MAC MD5
                                   01 00 - MD2.5
                                   02 00 - DES MAC
                                   04 00 - HMAC SHA1 DES3-KD
                                   11 00 - RC4-HMAC
    4..5           SEAL_ALG        ff ff - none
                                   00 00 - DES
                                   02 00 - DES3-KD
                                   10 00 - RC4-HMAC
    6..7           Filler          Contains ff ff
    8..15          SND_SEQ         Encrypted sequence number field.
    16..s+15       SGN_CKSUM       Checksum of plaintext padded data,
                                  calculated according to algorithm
                                 specified in SGN_ALG field.
    s+16..last     Data            encrypted or plaintext padded data

Where "s" indicates the size of the checksum.

As always, this is preceeded by a GSSHeader.
Author:
Mayank Upadhyay, Ram Marti
See Also:
GSSHeader/**
 * This class is a base class for other token definitions that pertain to
 * per-message GSS-API calls. Conceptually GSS-API has two types of
 * per-message tokens: WrapToken and MicToken. They differ in the respect
 * that a WrapToken carries additional plaintext or ciphertext application
 * data besides just the sequence number and checksum. This class
 * encapsulates the commonality in the structure of the WrapToken and the
 * MicToken. This structure can be represented as:
 * <p>
 * <pre>
 *     0..1           TOK_ID          Identification field.
 *                                    01 01 - Mic token
 *                                    02 01 - Wrap token
 *     2..3           SGN_ALG         Checksum algorithm indicator.
 *                                    00 00 - DES MAC MD5
 *                                    01 00 - MD2.5
 *                                    02 00 - DES MAC
 *                                    04 00 - HMAC SHA1 DES3-KD
 *                                    11 00 - RC4-HMAC
 *     4..5           SEAL_ALG        ff ff - none
 *                                    00 00 - DES
 *                                    02 00 - DES3-KD
 *                                    10 00 - RC4-HMAC
 *     6..7           Filler          Contains ff ff
 *     8..15          SND_SEQ         Encrypted sequence number field.
 *     16..s+15       SGN_CKSUM       Checksum of plaintext padded data,
 *                                   calculated according to algorithm
 *                                  specified in SGN_ALG field.
 *     s+16..last     Data            encrypted or plaintext padded data
 * </pre>
 * Where "s" indicates the size of the checksum.
 * <p>
 * As always, this is preceeded by a GSSHeader.
 *
 * @author Mayank Upadhyay
 * @author Ram Marti
 * @see sun.security.jgss.GSSHeader
 */

abstract class MessageToken extends Krb5Token {
    /* Fields in header minus checksum size */
    private static final int TOKEN_NO_CKSUM_SIZE = 16;

    
Filler data as defined in the specification of the Kerberos v5 GSS-API
Mechanism.
/**
     * Filler data as defined in the specification of the Kerberos v5 GSS-API
     * Mechanism.
     */
    private static final int FILLER = 0xffff;

     // Signing algorithm values (for the SNG_ALG field)

     // From RFC 1964
     /* Use a DES MAC MD5 checksum */
    static final int SGN_ALG_DES_MAC_MD5 = 0x0000;

     /* Use DES MAC checksum. */
    static final int SGN_ALG_DES_MAC     = 0x0200;

     // From draft-raeburn-cat-gssapi-krb5-3des-00
     /* Use a HMAC SHA1 DES3 -KD checksum */
    static final int SGN_ALG_HMAC_SHA1_DES3_KD = 0x0400;

     // Sealing algorithm values (for the SEAL_ALG field)

     // RFC 1964
    
A value for the SEAL_ALG field that indicates that no encryption was
used.
/**
     * A value for the SEAL_ALG field that indicates that no encryption was
     * used.
     */
    static final int SEAL_ALG_NONE    = 0xffff;
     /* Use DES CBC encryption algorithm. */
    static final int SEAL_ALG_DES = 0x0000;

    // From draft-raeburn-cat-gssapi-krb5-3des-00
    
Use DES3-KD sealing algorithm. (draft-raeburn-cat-gssapi-krb5-3des-00)
This algorithm uses triple-DES with key derivation, with a usage
value KG_USAGE_SEAL.  Padding is still to 8-byte multiples, and the
IV for encrypting application data is zero.
/**
     * Use DES3-KD sealing algorithm. (draft-raeburn-cat-gssapi-krb5-3des-00)
     * This algorithm uses triple-DES with key derivation, with a usage
     * value KG_USAGE_SEAL.  Padding is still to 8-byte multiples, and the
     * IV for encrypting application data is zero.
     */
    static final int SEAL_ALG_DES3_KD = 0x0200;

    // draft draft-brezak-win2k-krb-rc4-hmac-04.txt
    static final int SEAL_ALG_ARCFOUR_HMAC = 0x1000;
    static final int SGN_ALG_HMAC_MD5_ARCFOUR = 0x1100;

    private static final int TOKEN_ID_POS = 0;
    private static final int SIGN_ALG_POS = 2;
    private static final int SEAL_ALG_POS = 4;

    private int seqNumber;

    private boolean confState = true;
    private boolean initiator = true;

    private int tokenId = 0;
    private GSSHeader gssHeader = null;
    private MessageTokenHeader tokenHeader = null;
    private byte[] checksum = null;
    private byte[] encSeqNumber = null;
    private byte[] seqNumberData = null;

    /* cipher instance used by the corresponding GSSContext */
    CipherHelper cipherHelper = null;


    
Constructs a MessageToken from a byte array. If there are more bytes
in the array than needed, the extra bytes are simply ignroed.
Params:
tokenId – the token id that should be contained in this token as
it is read.
context – the Kerberos context associated with this token
tokenBytes – the byte array containing the token
tokenOffset – the offset where the token begins
tokenLen – the length of the token
prop – the MessageProp structure in which the properties of the
token should be stored.
Throws:
GSSException – if there is a problem parsing the token/**
     * Constructs a MessageToken from a byte array. If there are more bytes
     * in the array than needed, the extra bytes are simply ignroed.
     *
     * @param tokenId the token id that should be contained in this token as
     * it is read.
     * @param context the Kerberos context associated with this token
     * @param tokenBytes the byte array containing the token
     * @param tokenOffset the offset where the token begins
     * @param tokenLen the length of the token
     * @param prop the MessageProp structure in which the properties of the
     * token should be stored.
     * @throws GSSException if there is a problem parsing the token
     */
    MessageToken(int tokenId, Krb5Context context,
                 byte[] tokenBytes, int tokenOffset, int tokenLen,
                 MessageProp prop) throws GSSException {
        this(tokenId, context,
             new ByteArrayInputStream(tokenBytes, tokenOffset, tokenLen),
             prop);
    }

    
Constructs a MessageToken from an InputStream. Bytes will be read on
demand and the thread might block if there are not enough bytes to
complete the token.
Params:
tokenId – the token id that should be contained in this token as
it is read.
context – the Kerberos context associated with this token
is – the InputStream from which to read
prop – the MessageProp structure in which the properties of the
token should be stored.
Throws:
GSSException – if there is a problem reading from the
InputStream or parsing the token/**
     * Constructs a MessageToken from an InputStream. Bytes will be read on
     * demand and the thread might block if there are not enough bytes to
     * complete the token.
     *
     * @param tokenId the token id that should be contained in this token as
     * it is read.
     * @param context the Kerberos context associated with this token
     * @param is the InputStream from which to read
     * @param prop the MessageProp structure in which the properties of the
     * token should be stored.
     * @throws GSSException if there is a problem reading from the
     * InputStream or parsing the token
     */
    MessageToken(int tokenId, Krb5Context context, InputStream is,
                 MessageProp prop) throws GSSException {
        init(tokenId, context);

        try {
            gssHeader = new GSSHeader(is);

            if (!gssHeader.getOid().equals(OID)) {
                throw new GSSException(GSSException.DEFECTIVE_TOKEN, -1,
                                       getTokenName(tokenId));
            }
            if (!confState) {
                prop.setPrivacy(false);
            }

            tokenHeader = new MessageTokenHeader(is, prop);

            encSeqNumber = new byte[8];
            readFully(is, encSeqNumber);

            // debug("\n\tRead EncSeq#=" +
            // getHexBytes(encSeqNumber, encSeqNumber.length));

            checksum = new byte[cipherHelper.getChecksumLength()];
            readFully(is, checksum);

            // debug("\n\tRead checksum=" +
            // getHexBytes(checksum, checksum.length));
            // debug("\nLeaving MessageToken.Cons\n");

        } catch (IOException e) {
            throw new GSSException(GSSException.DEFECTIVE_TOKEN, -1,
                getTokenName(tokenId) + ":" + e.getMessage());
        }
    }

    
Used to obtain the GSSHeader that was at the start of this
token.
/**
     * Used to obtain the GSSHeader that was at the start of this
     * token.
     */
    public final GSSHeader getGSSHeader() {
        return gssHeader;
    }

    
Used to obtain the token id that was contained in this token.
Returns:
the token id in the token/**
     * Used to obtain the token id that was contained in this token.
     * @return the token id in the token
     */
    public final int getTokenId() {
        return tokenId;
    }

    
Used to obtain the encrypted sequence number in this token.
Returns:
the encrypted sequence number in the token/**
     * Used to obtain the encrypted sequence number in this token.
     * @return the encrypted sequence number in the token
     */
    public final byte[] getEncSeqNumber() {
        return encSeqNumber;
    }

    
Used to obtain the checksum that was contained in this token.
Returns:
the checksum in the token/**
     * Used to obtain the checksum that was contained in this token.
     * @return the checksum in the token
     */
    public final byte[] getChecksum() {
        return checksum;
    }

    
Used to determine if this token contains any encrypted data.
Returns:
true if it contains any encrypted data, false if there is only
plaintext data or if there is no data./**
     * Used to determine if this token contains any encrypted data.
     * @return true if it contains any encrypted data, false if there is only
     * plaintext data or if there is no data.
     */
    public final boolean getConfState() {
        return confState;
    }

    
Generates the checksum field and the encrypted sequence number
field. The encrypted sequence number uses the 8 bytes of the checksum
as an initial vector in a fixed DesCbc algorithm.
Params:
prop – the MessageProp structure that determines what sort of
checksum and sealing algorithm should be used. The lower byte
of qop determines the checksum algorithm while the upper byte
determines the signing algorithm.
      Checksum values are:
          0 - default (DES_MAC)
          1 - MD5
          2 - DES_MD5
          3 - DES_MAC
          4 - HMAC_SHA1
      Sealing values are:
          0 - default (DES)
          1 - DES
          2 - DES3-KD
optionalHeader – an optional header that will be processed first
during  checksum calculation
data – the application data to checksum
offset – the offset where the data starts
len – the length of the data
optionalTrailer – an optional trailer that will be processed
last during checksum calculation. e.g., padding that should be
appended to the application data
Throws:
GSSException – if an error occurs in the checksum calculation or
encryption sequence number calculation./**
     * Generates the checksum field and the encrypted sequence number
     * field. The encrypted sequence number uses the 8 bytes of the checksum
     * as an initial vector in a fixed DesCbc algorithm.
     *
     * @param prop the MessageProp structure that determines what sort of
     * checksum and sealing algorithm should be used. The lower byte
     * of qop determines the checksum algorithm while the upper byte
     * determines the signing algorithm.
     *       Checksum values are:
     *           0 - default (DES_MAC)
     *           1 - MD5
     *           2 - DES_MD5
     *           3 - DES_MAC
     *           4 - HMAC_SHA1
     *       Sealing values are:
     *           0 - default (DES)
     *           1 - DES
     *           2 - DES3-KD
     *
     * @param optionalHeader an optional header that will be processed first
     * during  checksum calculation
     *
     * @param data the application data to checksum
     * @param offset the offset where the data starts
     * @param len the length of the data
     *
     * @param optionalTrailer an optional trailer that will be processed
     * last during checksum calculation. e.g., padding that should be
     * appended to the application data
     *
     * @throws GSSException if an error occurs in the checksum calculation or
     * encryption sequence number calculation.
     */
    public void genSignAndSeqNumber(MessageProp prop,
                                    byte[] optionalHeader,
                                    byte[] data, int offset, int len,
                                    byte[] optionalTrailer)
        throws GSSException {

        //    debug("Inside MessageToken.genSignAndSeqNumber:\n");

        int qop = prop.getQOP();
        if (qop != 0) {
            qop = 0;
            prop.setQOP(qop);
        }

        if (!confState) {
            prop.setPrivacy(false);
        }

        // Create a token header with the correct sign and seal algorithm
        // values.
        tokenHeader =
            new MessageTokenHeader(tokenId, prop.getPrivacy(), qop);

        // Calculate SGN_CKSUM

        checksum =
            getChecksum(optionalHeader, data, offset, len, optionalTrailer);

        // debug("\n\tCalc checksum=" +
        // getHexBytes(checksum, checksum.length));

        // Calculate SND_SEQ

        seqNumberData = new byte[8];

        // When using this RC4 based encryption type, the sequence number is
        // always sent in big-endian rather than little-endian order.
        if (cipherHelper.isArcFour()) {
            writeBigEndian(seqNumber, seqNumberData);
        } else {
            // for all other etypes
            writeLittleEndian(seqNumber, seqNumberData);
        }
        if (!initiator) {
            seqNumberData[4] = (byte)0xff;
            seqNumberData[5] = (byte)0xff;
            seqNumberData[6] = (byte)0xff;
            seqNumberData[7] = (byte)0xff;
        }

        encSeqNumber = cipherHelper.encryptSeq(checksum, seqNumberData, 0, 8);

        // debug("\n\tCalc seqNum=" +
        //    getHexBytes(seqNumberData, seqNumberData.length));
        // debug("\n\tCalc encSeqNum=" +
        //    getHexBytes(encSeqNumber, encSeqNumber.length));
    }

    
Verifies that the checksum field and sequence number direction bytes
are valid and consistent with the application data.
Params:
optionalHeader – an optional header that will be processed first
during checksum calculation.
data – the application data
offset – the offset where the data begins
len – the length of the application data
optionalTrailer – an optional trailer that will be processed last
during checksum calculation. e.g., padding that should be appended to
the application data
Throws:
GSSException – if an error occurs in the checksum calculation or
encryption sequence number calculation./**
     * Verifies that the checksum field and sequence number direction bytes
     * are valid and consistent with the application data.
     *
     * @param optionalHeader an optional header that will be processed first
     * during checksum calculation.
     *
     * @param data the application data
     * @param offset the offset where the data begins
     * @param len the length of the application data
     *
     * @param optionalTrailer an optional trailer that will be processed last
     * during checksum calculation. e.g., padding that should be appended to
     * the application data
     *
     * @throws GSSException if an error occurs in the checksum calculation or
     * encryption sequence number calculation.
     */
    public final boolean verifySignAndSeqNumber(byte[] optionalHeader,
                                        byte[] data, int offset, int len,
                                        byte[] optionalTrailer)
        throws GSSException {
         // debug("\tIn verifySign:\n");

         // debug("\t\tchecksum:   [" + getHexBytes(checksum) + "]\n");

        byte[] myChecksum =
            getChecksum(optionalHeader, data, offset, len, optionalTrailer);

        // debug("\t\tmychecksum: [" + getHexBytes(myChecksum) +"]\n");
        // debug("\t\tchecksum:   [" + getHexBytes(checksum) + "]\n");

        if (MessageDigest.isEqual(checksum, myChecksum)) {

            seqNumberData = cipherHelper.decryptSeq(
                checksum, encSeqNumber, 0, 8);

            // debug("\t\tencSeqNumber:   [" + getHexBytes(encSeqNumber)
            //  + "]\n");
            // debug("\t\tseqNumberData:   [" + getHexBytes(seqNumberData)
            //  + "]\n");

            /*
             * The token from the initiator has direction bytes 0x00 and
             * the token from the acceptor has direction bytes 0xff.
             */
            byte directionByte = 0;
            if (initiator)
                directionByte = (byte) 0xff; // Received token from acceptor

            if ((seqNumberData[4] == directionByte) &&
                  (seqNumberData[5] == directionByte) &&
                  (seqNumberData[6] == directionByte) &&
                  (seqNumberData[7] == directionByte))
                return true;
        }

        return false;

    }

    public final int getSequenceNumber() {
        int sequenceNum = 0;
        if (cipherHelper.isArcFour()) {
            sequenceNum = readBigEndian(seqNumberData, 0, 4);
        } else {
            sequenceNum = readLittleEndian(seqNumberData, 0, 4);
        }
        return sequenceNum;
    }

    
Computes the checksum based on the algorithm stored in the
tokenHeader.
Params:
optionalHeader – an optional header that will be processed first
during checksum calculation.
data – the application data
offset – the offset where the data begins
len – the length of the application data
optionalTrailer – an optional trailer that will be processed last
during checksum calculation. e.g., padding that should be appended to
the application data
Throws:
GSSException – if an error occurs in the checksum calculation./**
     * Computes the checksum based on the algorithm stored in the
     * tokenHeader.
     *
     * @param optionalHeader an optional header that will be processed first
     * during checksum calculation.
     *
     * @param data the application data
     * @param offset the offset where the data begins
     * @param len the length of the application data
     *
     * @param optionalTrailer an optional trailer that will be processed last
     * during checksum calculation. e.g., padding that should be appended to
     * the application data
     *
     * @throws GSSException if an error occurs in the checksum calculation.
     */
    private byte[] getChecksum(byte[] optionalHeader,
                               byte[] data, int offset, int len,
                               byte[] optionalTrailer)
        throws GSSException {

        //      debug("Will do getChecksum:\n");

        /*
         * For checksum calculation the token header bytes i.e., the first 8
         * bytes following the GSSHeader, are logically prepended to the
         * application data to bind the data to this particular token.
         *
         * Note: There is no such requirement wrt adding padding to the
         * application data for checksumming, although the cryptographic
         * algorithm used might itself apply some padding.
         */

        byte[] tokenHeaderBytes = tokenHeader.getBytes();
        byte[] existingHeader = optionalHeader;
        byte[] checksumDataHeader = tokenHeaderBytes;

        if (existingHeader != null) {
            checksumDataHeader = new byte[tokenHeaderBytes.length +
                                         existingHeader.length];
            System.arraycopy(tokenHeaderBytes, 0,
                             checksumDataHeader, 0, tokenHeaderBytes.length);
            System.arraycopy(existingHeader, 0,
                             checksumDataHeader, tokenHeaderBytes.length,
                             existingHeader.length);
        }

        return cipherHelper.calculateChecksum(tokenHeader.getSignAlg(),
             checksumDataHeader, optionalTrailer, data, offset, len, tokenId);
    }


    
Constructs an empty MessageToken for the local context to send to
the peer. It also increments the local sequence number in the
Krb5Context instance it uses after obtaining the object lock for
it.
Params:
tokenId – the token id that should be contained in this token
context – the Kerberos context associated with this token/**
     * Constructs an empty MessageToken for the local context to send to
     * the peer. It also increments the local sequence number in the
     * Krb5Context instance it uses after obtaining the object lock for
     * it.
     *
     * @param tokenId the token id that should be contained in this token
     * @param context the Kerberos context associated with this token
     */
    MessageToken(int tokenId, Krb5Context context) throws GSSException {
        /*
          debug("\n============================");
          debug("\nMySessionKey=" +
          getHexBytes(context.getMySessionKey().getBytes()));
          debug("\nPeerSessionKey=" +
          getHexBytes(context.getPeerSessionKey().getBytes()));
          debug("\n============================\n");
        */
        init(tokenId, context);
        this.seqNumber = context.incrementMySequenceNumber();
    }

    private void init(int tokenId, Krb5Context context) throws GSSException {
        this.tokenId = tokenId;
        // Just for consistency check in Wrap
        this.confState = context.getConfState();

        this.initiator = context.isInitiator();

        this.cipherHelper = context.getCipherHelper(null);
        //    debug("In MessageToken.Cons");
    }

    
Encodes a GSSHeader and this token onto an OutputStream.
Params:
os – the OutputStream to which this should be written
Throws:
GSSException – if an error occurs while writing to the OutputStream/**
     * Encodes a GSSHeader and this token onto an OutputStream.
     *
     * @param os the OutputStream to which this should be written
     * @throws GSSException if an error occurs while writing to the OutputStream
     */
    public void encode(OutputStream os) throws IOException, GSSException {
        gssHeader = new GSSHeader(OID, getKrb5TokenSize());
        gssHeader.encode(os);
        tokenHeader.encode(os);
        // debug("Writing seqNumber: " + getHexBytes(encSeqNumber));
        os.write(encSeqNumber);
        // debug("Writing checksum: " + getHexBytes(checksum));
        os.write(checksum);
    }

    
Obtains the size of this token. Note that this excludes the size of
the GSSHeader.
Returns:
token size/**
     * Obtains the size of this token. Note that this excludes the size of
     * the GSSHeader.
     * @return token size
     */
    protected int getKrb5TokenSize() throws GSSException {
        return getTokenSize();
    }

    protected final int getTokenSize() throws GSSException {
        return TOKEN_NO_CKSUM_SIZE + cipherHelper.getChecksumLength();
    }

    protected static final int getTokenSize(CipherHelper ch)
        throws GSSException {
         return TOKEN_NO_CKSUM_SIZE + ch.getChecksumLength();
    }

    /**
     * Obtains the conext key that is associated with this token.
     * @return the context key
     */
    /*
    public final byte[] getContextKey() {
        return contextKey;
    }
    */

    
Obtains the encryption algorithm that should be used in this token
given the state of confidentiality the application requested.
Requested qop must be consistent with negotiated session key.
Params:
confRequested – true if the application desired confidentiality
on this token, false otherwise
qop – the qop requested by the application
Throws:
GSSException – if qop is incompatible with the negotiated
        session key/**
     * Obtains the encryption algorithm that should be used in this token
     * given the state of confidentiality the application requested.
     * Requested qop must be consistent with negotiated session key.
     * @param confRequested true if the application desired confidentiality
     * on this token, false otherwise
     * @param qop the qop requested by the application
     * @throws GSSException if qop is incompatible with the negotiated
     *         session key
     */
    protected abstract int getSealAlg(boolean confRequested, int qop)
        throws GSSException;

    // ******************************************* //
    //  I N N E R    C L A S S E S    F O L L O W
    // ******************************************* //

    
This inner class represents the initial portion of the message token
and contains information about the checksum and encryption algorithms
that are in use. It constitutes the first 8 bytes of the
message token:
    0..1           TOK_ID          Identification field.
                                   01 01 - Mic token
                                   02 01 - Wrap token
    2..3           SGN_ALG         Checksum algorithm indicator.
                                   00 00 - DES MAC MD5
                                   01 00 - MD2.5
                                   02 00 - DES MAC
                                   04 00 - HMAC SHA1 DES3-KD
                                   11 00 - RC4-HMAC
    4..5           SEAL_ALG        ff ff - none
                                   00 00 - DES
                                   02 00 - DES3-KD
                                   10 00 - RC4-HMAC
    6..7           Filler          Contains ff ff

/**
     * This inner class represents the initial portion of the message token
     * and contains information about the checksum and encryption algorithms
     * that are in use. It constitutes the first 8 bytes of the
     * message token:
     * <pre>
     *     0..1           TOK_ID          Identification field.
     *                                    01 01 - Mic token
     *                                    02 01 - Wrap token
     *     2..3           SGN_ALG         Checksum algorithm indicator.
     *                                    00 00 - DES MAC MD5
     *                                    01 00 - MD2.5
     *                                    02 00 - DES MAC
     *                                    04 00 - HMAC SHA1 DES3-KD
     *                                    11 00 - RC4-HMAC
     *     4..5           SEAL_ALG        ff ff - none
     *                                    00 00 - DES
     *                                    02 00 - DES3-KD
     *                                    10 00 - RC4-HMAC
     *     6..7           Filler          Contains ff ff
     * </pre>
     */
    class MessageTokenHeader {

         private int tokenId;
         private int signAlg;
         private int sealAlg;

         private byte[] bytes = new byte[8];

        
Constructs a MessageTokenHeader for the specified token type with
appropriate checksum and encryption algorithms fields.
Params:
tokenId – the token id for this message token
conf – true if confidentiality will be resuested with this
message token, false otherwise.
qop – the value of the quality of protection that will be
desired./**
         * Constructs a MessageTokenHeader for the specified token type with
         * appropriate checksum and encryption algorithms fields.
         *
         * @param tokenId the token id for this message token
         * @param conf true if confidentiality will be resuested with this
         * message token, false otherwise.
         * @param qop the value of the quality of protection that will be
         * desired.
         */
        public MessageTokenHeader(int tokenId, boolean conf, int qop)
         throws GSSException {

            this.tokenId = tokenId;

            signAlg = MessageToken.this.getSgnAlg(qop);

            sealAlg = MessageToken.this.getSealAlg(conf, qop);

            bytes[0] = (byte) (tokenId >>> 8);
            bytes[1] = (byte) (tokenId);

            bytes[2] = (byte) (signAlg >>> 8);
            bytes[3] = (byte) (signAlg);

            bytes[4] = (byte) (sealAlg >>> 8);
            bytes[5] = (byte) (sealAlg);

            bytes[6] = (byte) (MessageToken.FILLER >>> 8);
            bytes[7] = (byte) (MessageToken.FILLER);
        }

        
Constructs a MessageTokenHeader by reading it from an InputStream
and sets the appropriate confidentiality and quality of protection
values in a MessageProp structure.
Params:
is – the InputStream to read from
prop – the MessageProp to populate
Throws:
IOException – is an error occurs while reading from the
InputStream/**
         * Constructs a MessageTokenHeader by reading it from an InputStream
         * and sets the appropriate confidentiality and quality of protection
         * values in a MessageProp structure.
         *
         * @param is the InputStream to read from
         * @param prop the MessageProp to populate
         * @throws IOException is an error occurs while reading from the
         * InputStream
         */
        public MessageTokenHeader(InputStream is, MessageProp prop)
            throws IOException {
            readFully(is, bytes);
            tokenId = readInt(bytes, TOKEN_ID_POS);
            signAlg = readInt(bytes, SIGN_ALG_POS);
            sealAlg = readInt(bytes, SEAL_ALG_POS);
            //          debug("\nMessageTokenHeader read tokenId=" +
            //                getHexBytes(bytes) + "\n");
            // XXX compare to FILLER
            int temp = readInt(bytes, SEAL_ALG_POS + 2);

            //              debug("SIGN_ALG=" + signAlg);

            switch (sealAlg) {
            case SEAL_ALG_DES:
            case SEAL_ALG_DES3_KD:
            case SEAL_ALG_ARCFOUR_HMAC:
                prop.setPrivacy(true);
                break;

            default:
                prop.setPrivacy(false);
            }

            prop.setQOP(0);  // default
        }

        
Encodes this MessageTokenHeader onto an OutputStream
Params:
os – the OutputStream to write to
Throws:
IOException – is an error occurs while writing/**
         * Encodes this MessageTokenHeader onto an OutputStream
         * @param os the OutputStream to write to
         * @throws IOException is an error occurs while writing
         */
        public final void encode(OutputStream os) throws IOException {
            os.write(bytes);
        }


        
Returns the token id for the message token.
See Also:
Krb5Token.MIC_ID
Krb5Token.WRAP_ID
Returns:
the token id/**
         * Returns the token id for the message token.
         * @return the token id
         * @see sun.security.jgss.krb5.Krb5Token#MIC_ID
         * @see sun.security.jgss.krb5.Krb5Token#WRAP_ID
         */
        public final int getTokenId() {
            return tokenId;
        }

        
Returns the sign algorithm for the message token.
See Also:
MessageToken.SIGN_DES_MAC
MessageToken.SIGN_DES_MAC_MD5
Returns:
the sign algorithm/**
         * Returns the sign algorithm for the message token.
         * @return the sign algorithm
         * @see sun.security.jgss.krb5.MessageToken#SIGN_DES_MAC
         * @see sun.security.jgss.krb5.MessageToken#SIGN_DES_MAC_MD5
         */
        public final int getSignAlg() {
            return signAlg;
        }

        
Returns the seal algorithm for the message token.
See Also:
MessageToken.SEAL_ALG_DES
MessageToken.SEAL_ALG_NONE
Returns:
the seal algorithm/**
         * Returns the seal algorithm for the message token.
         * @return the seal algorithm
         * @see sun.security.jgss.krb5.MessageToken#SEAL_ALG_DES
         * @see sun.security.jgss.krb5.MessageToken#SEAL_ALG_NONE
         */
        public final int getSealAlg() {
            return sealAlg;
        }

        
Returns the bytes of this header.
Returns:
8 bytes that form this header/**
         * Returns the bytes of this header.
         * @return 8 bytes that form this header
         */
        public final byte[] getBytes() {
            return bytes;
        }
    } // end of class MessageTokenHeader


    
Determine signing algorithm based on QOP.
/**
     * Determine signing algorithm based on QOP.
     */
    protected int getSgnAlg(int qop) throws GSSException {
         // QOP ignored
         return cipherHelper.getSgnAlg();
    }
}