## 7 Scientific Issues and Deployment Implementation Routes
### The Key Technologies
Aimed at the processing mode of distributed collection and acquisition of ATM business data by ATM system equipment, the structure framework of security situation awareness system of ATM system based on multi-sensor is studied (divided into three levels from bottom to top: information collection level, element extraction level, and situation decision-making level), and the network physical structure of ATM system and the hierarchical model of equipment layer, transmission layer, and application layer are designed. On the basis of the structural framework of the security situation awareness system of the ATM system, the eXML format solution for multi-source heterogeneous security information of the ATM system is proposed. It includes three steps: detection data fusion, establishment of threat propagation network (TPN), and evaluation of CPS game model. The CPS game model is used to comprehensively evaluate the security situation of each resource subsystem of the ATM system from the perspectives of attack and defense, and the development trend of the security situation of the entire networked ATM system is obtained through the quantitative evaluation method of network security situation, thus providing a reference for timely adjustment of the system security strategy. * Situation prediction. The deep learning model is used to predict the security situation of networked ATM system. First, we sort out the network attack events suffered by the networked ATM, study the method of event embedding, express the security events as dense vectors using neural tensor network (NTN), and conduct security event training. Then, the deep convolutional neural network is used to model the impact of security incidents, and a dynamic prediction model of networked ATM system security situation is established on the basis of the deep convolutional neural network. Genetic algorithm is used to optimize the model and realize the nonlinear time series prediction of the security situation of networked ATM system. * Building trust mechanism technology of networked ATM based on blockchain. On the basis of the open-source licensing blockchain framework and in combination with the business characteristics and processes of the ATM, the point-to-point network design, the application of cryptographic technology, the implementation of distributed algorithms, and the development of data storage technology for the networked ATM are completed. The goal is to establish a blockchain-based trust model for the networked ATM, study the information security assurance architecture of the networked ATM based on the trusted model, and realize the data security and privacy protection of the ATM. Meanwhile, secure communication among the ATM departments, airlines, airports, and other operation support units or other authorized entities in the space-air-ground integrated ATM network can be guaranteed. The functions realized include:
* Adopt the characteristics of blockchain decentralization, asymmetric encryption, distributed storage, etc., and realize point-to-point communication in the ATM system through the distributed accounting method of the underlying public chain so as to ensure that all devices in the ATM system can securely exchange data in a trusted environment;
* Adopt smart contract technology to convert and write the registered network access information of all component resource subsystem equipment in the ATM into the blockchain. The characteristics of blockchain technology ensure that the entire process of storage, reading, and execution of business data of ATM is transparent, traceable, and tamper-proof. It can solve the trust problems among the equipment of the ATM, airlines, airports, and ATM departments and between the ATM operators and the ATM;
* Establish a tamper-proof intelligent trust mechanism in the networked ATM system by using the blockchain network; this can resist the tampering of core data by internal personnel of the ATM, identify false data injection, and resist the deceptive attack facing satellite navigation information.