bufferIndex += 4;
        this.server.serverTime = SMBUtil.readTime(buffer, bufferIndex);
        bufferIndex += 8;
        int tzOffset = SMBUtil.readInt2(buffer, bufferIndex);
        // tzOffset is signed!
        if ( tzOffset > Short.MAX_VALUE ) {
            tzOffset = -1 * ( 65536 - tzOffset );
        }
        this.server.serverTimeZone = tzOffset;
        bufferIndex += 2;

     */
    @Override
    public final boolean isError () {
        return this.error;
    }


    /**
     * @return whether the packet has been signed.
     */
    public boolean isSigned () {
        return ( getFlags() & SMB2_FLAGS_SIGNED ) != 0;
    }


    /**
     * {@inheritDoc}
     *
     * @see jcifs.util.transport.Response#getExpiration()
     */
    @Override

    /**
     * 
     */
    public static final int SMB2_FLAGS_RELATED_OPERATIONS = 0x00000004;
    /**
     * 
     */
    public static final int SMB2_FLAGS_SIGNED = 0x00000008;
    /**
     * 
     */
    public static final int SMB2_FLAGS_PRIORITY_MASK = 0x00000070;
    /**
     * 
     */
    public static final int SMB2_FLAGS_DFS_OPERATIONS = 0x10000000;
    /**

        int index = offset + SIGNATURE_OFFSET;
        for ( int i = 0; i < SIGNATURE_LENGTH; i++ )
            data[ index + i ] = 0;

        // set signed flag
        int oldFlags = SMBUtil.readInt4(data, offset + 16);
        int flags = oldFlags | ServerMessageBlock2.SMB2_FLAGS_SIGNED;
        SMBUtil.writeInt4(flags, data, offset + 16);

        this.digest.update(data, offset, length);

                    System.arraycopy(sk, 0, key, 0, Math.min(16, sk.length));
                    this.sessionKey = key;
                }

                boolean signed = response != null && response.isSigned();
                if ( !anonymous && ( isSignatureSetupRequired() || signed ) ) {
                    byte[] signingKey = ctx.getSigningKey();
                    if ( signingKey != null && response != null ) {

        if ( ( msg.getFlags2() & SmbConstants.FLAGS2_SECURITY_SIGNATURES ) == 0 ) {
            // signature requirements need to be checked somewhere else
            log.warn("Expected signed response, but is not signed");
            return false;
        }

        update(this.macSigningKey, 0, this.macSigningKey.length);
        int index = offset;
        update(data, index, SmbConstants.SIGNATURE_OFFSET);