if (isRetainPayload()) {
            final byte[] payload = new byte[len];
            System.arraycopy(buffer, 4, payload, 0, len);
            setRawPayload(payload);
        }

        if (!verifySignature(buffer, 4, len)) {
            throw new SMBProtocolDecodingException("Signature verification failed for " + this.getClass().getName());
        }
        return len;
    }

    /**

                            response.setDigest(dgst);
                            byte[] payload = response.getRawPayload();
                            if (!response.verifySignature(payload, 0, payload.length)) {
                                throw new SmbException("Signature validation failed");
                            }
                        }
                        setDigest(dgst);