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);

        byte[] sig = this.digest.doFinal();
        System.arraycopy(sig, 0, data, offset + SIGNATURE_OFFSET, SIGNATURE_LENGTH);
    }


    /**
     * 
     * {@inheritDoc}

            break;
        default:
            throw new SmbUnsupportedOperationException();
        }

        if ( oldHash != null ) {
            dgst.update(oldHash);
        }
        dgst.update(input, off, len);
        return dgst.digest();
    }


    Cipher createEncryptionCipher ( byte[] key ) throws CIFSException {
        if ( !this.smb2 || this.negotiated == null ) {