return u * v / a;
    }


    /**
     * @param type
     * @param keys
     * @return the calculated mac
     * @throws PACDecodingException
     */
    public static byte[] calculateMac ( int type, Map<Integer, KerberosKey> keys, byte[] data ) throws PACDecodingException {
        try {
            int usage = 17;
            if ( type == PacSignature.KERB_CHECKSUM_HMAC_MD5 ) {

                    this.serverSignature.getType(),
                    Hexdump.toHexString(this.serverSignature.getChecksum())));
        }

        byte checksum[] = PacMac.calculateMac(this.serverSignature.getType(), keys, checksumData);
        if ( !MessageDigest.isEqual(this.serverSignature.getChecksum(), checksum) ) {
            if ( log.isDebugEnabled() ) {
                log.debug(

        return this.mechContext.isPreferredMech(mech);
    }


    @Override
    public byte[] calculateMIC ( byte[] data ) throws CIFSException {
        if ( !this.completed ) {
            throw new CIFSException("Context is not established");
        }
        return this.mechContext.calculateMIC(data);
    }


    /**
     * {@inheritDoc}
     *

     * @return whether this mechanisms supports integrity
     */
    boolean supportsIntegrity ();


    /**
     * @param data
     * @return MIC
     * @throws CIFSException
     */
    byte[] calculateMIC ( byte[] data ) throws CIFSException;


    /**
     * @param data
     * @param mic
     * @throws CIFSException
     */
    void verifyMIC ( byte[] data, byte[] mic ) throws CIFSException;

        return true;
    }


    /**
     * {@inheritDoc}
     * 
     * @throws CIFSException
     *
     * @see jcifs.smb.SSPContext#calculateMIC(byte[])
     */
    @Override
    public byte[] calculateMIC ( byte[] data ) throws CIFSException {
        try {
            return this.gssContext.getMIC(data, 0, data.length, new MessageProp(false));
        }

    }


    @Override
    public boolean isMICAvailable () {
        return !this.auth.isGuest() && this.signKey != null && this.verifyKey != null;
    }


    @Override
    public byte[] calculateMIC ( byte[] data ) throws CIFSException {
        byte[] sk = this.signKey;
        if ( sk == null ) {
            throw new CIFSException("Signing is not initialized");
        }