}

        if ( usage == 0 ) {
            if ( log.isTraceEnabled() ) {
                log.trace("Transport usage dropped to zero " + this);
            }
        }
        else if ( usage < 0 ) {
            throw new RuntimeCIFSException("Usage count dropped below zero");
        }
    }


    /**
     * {@inheritDoc}
     *
     * @see java.lang.Object#finalize()
     */

     */
    public boolean isEmpty () {
        return this.sub_authority_count == 0;
    }


    /**
     * 
     * @return whether the SID is blank (all sub-authorities zero)
     */
    public boolean isBlank () {
        boolean blank = true;
        for ( int sub : this.sub_authority )
            blank = blank && ( sub == 0 );
        return blank;
    }


    /**

    static final byte SMB_COM_NT_CREATE_ANDX     = (byte)0xA2;

    /*
     * Some fields specify the offset from the beginning of the header. This
     * field should be used for calculating that. This would likely be zero
     * but an implemantation that encorporates the transport header(for
     * efficiency) might use a different initial bufferIndex. For example,
     * to eliminate copying data when writing NbtSession data one might

            synchronized ( this ) {
                log.debug("Usage dropped to zero, release session");
                if ( this.sessionAcquired.compareAndSet(true, false) ) {
                    this.session.release();
                }
            }
        }
        else if ( usage < 0 ) {
            log.error("Usage count dropped below zero " + this);
            dumpResource();

                fail("EOF while reading");
            }
            pos += r;
        }

        for ( int i = 0; i < offBuf.length; i++ ) {
            if ( offBuf[ i ] != 0 ) {
                fail("Not zero @ " + i);
            }
        }
    }


    /**
     * @param bufSize
     * @param length
     * @param is
     * @throws IOException
     */

    public static final byte SMB_COM_NT_CREATE_ANDX = (byte) 0xA2;

    /*
     * Some fields specify the offset from the beginning of the header. This
     * field should be used for calculating that. This would likely be zero
     * but an implemantation that encorporates the transport header(for
     * efficiency) might use a different initial bufferIndex. For example,
     * to eliminate copying data when writing NbtSession data one might

                    }
                }
            }
        }
        else if ( usage < 0 ) {
            log.error("Usage count dropped below zero " + this);
            throw new RuntimeCIFSException("Usage count dropped below zero");
        }
    }


    protected void checkRelease () {
        if ( isConnected() && this.usageCount.get() != 0 ) {

     */
    public SMB1SigningDigest ( byte[] macSigningKey ) {
        this.digest = Crypto.getMD5();
        this.macSigningKey = macSigningKey;
    }


    /**
     * Construct a digest with a non-zero starting sequence number
     * 
     * @param macSigningKey
     * @param initialSequence
     */
    public SMB1SigningDigest ( byte[] macSigningKey, int initialSequence ) {
        this.digest = Crypto.getMD5();