## 3 Experimental Structure and Description  
It is necessary to design a solution to address the transformation of communication information data systems due to the current practical limitations of network communication technology. In our research, we have developed a novel framework that includes a blockchain security agent service model. This model implements encrypted message conversion at the application layer level through an agent, ensuring that all data expected to be transmitted by the sensing device undergo the necessary critical conversion process. Therefore, we redesigned a communication encryption application model based on the upper layer of TCP/IP to improve the security and performance of the overall system. This research applies a blockchain security agent service model to handle the conversion of communication information, ensuring data integrity and confidentiality. Through agent intervention, we can achieve a higher standard of security. When dealing with sensitive data, it is essential to avoid multiple reads or tampering, as this may affect the accuracy of the data. In addition, we have designed an approach that can be applied in different network environments, including blockchain methods with additional permissions. Smart contracts record the status and process information of all key exchanges. In this study, the communication mechanism of the Internet of Things (IoT) system is thoroughly investigated in the connection environment of the communication layer. The primary mechanism mainly depends on the broker, which facilitates the services of registering and subscribing. Once all the edge nodes are registered, by subscribing to the same topic they can access the various data information provided by the endpoints of different devices. A notable feature of this mechanism is that when a node sends a message, all the subscribers will receive the same content information simultaneously. We have redesigned the critical exchange model based on a standard communication architecture to address security concerns. Each node is responsible for creating its own public and private keys, emphasizing active key management, and preventing data leakage through unauthorized connections. In addition, we assume that each IoT device has registered with the Certificate Authority (CA) server and obtained its key. Public critical information is broadcasted to all nodes using the MQTT protocol. This process ensures the security of the key. It also establishes a reliable and secure channel for node communication. The public key-based communication encryption mode helps protect the integrity and confidentiality of data, which further enhances the overall security of the system. In this study, we focus on the security issues at the communication level of the Internet of Things, and the design plan is as follows in Figure 3.  
In this study, we changed the system design. We no longer relied solely on MQTT to register hardware devices but instead subscribed the hardware devices to the communication intermediary environment. Therefore, we will distribute the keys required by all nodes with the broadcast environment instead of just registering through a single MQTT channel. In our research, we handle key delivery and message delivery separately. We only provide subscriptions for specific topics (such as key-type notes) when subscribing to messages. Before communication between endpoints, keys will be exchanged, and pre-deployment will be completed before contact. The design of this offload operation ensures the security of communication and the correct transmission of keys between endpoints. This is a more effective and secure communication mechanism. According to our design architecture in Figure 3, the packets of the key will first pass through the red-dotted radio operation. We assume that node A generates a pair of public and private keys and broadcasts the public key. However, the public key cannot be successfully retrieved in the case of node D, a non-gold participant.