Wireless networks allow the download of large contents on the move, but the service range is limited and there can be frequent disconnects as the mobile user moves around, making it difficult to maintain a consistent communication quality. DTN is garnering attention as the solution to these problems, including for the military operational environment where large amounts of data are handled. But going beyond the simple exchange of data, studies on aspects of security are needed, such as data

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... identiality and flexible access control. To perform these security functions flexibly, secure sharing of data is needed as the prerequisite. The target of data sharing shares with the nodes managed by a cluster header. According to the attributes of the nodes involved, encrypted data are shared. In existing studies on methods based on DTN, the operation starts when a disconnect in the communication is detected by the bundle layer. In this paper, this is performed using an entity called a fog-computing-based proxy, as a specific hierarchical structure of the bundle layer. Especially, the design takes into account data sharing by a proxy, taking into account real-time network bandwidth, etc., so that data can be processed in the cluster. By using the CP-ABPRE method used in this paper, data confidentiality can be ensured, which has been a problem for DTN, and the reliability of the network using a proxy can be improved. In addition, a smart DTN model is suggested for the tactical network environment. This chapter explains the makeup and procedures of the proposed system model. Overview This section presents the model for a method of sharing the information sensed in the battlefield. This model is shown in Figure 1 . In DTN, the bundle layer plays the role of a fog in fog computing. In this paper, the proxy is taken into account along with the fog. Therefore the bundle layer performs a proxy-based security role. When CP-ABPRE is applied to this, secure sharing is made possible. As for the data transmission method, the node that has sensed battlefield data transmits them to the C4I server via a cluster header, which is the gateway of the local network (see Figure 1 ). Simultaneously to the node uploading the data to the C4I