中村 繁成

In the Fog Comput$ing (FC) model of the Internet of Things (IoT), application processes to handle sensor data are distributed to fog nodes and servers. In the Tree-based FC (TBFC) model proposed by the authors, fog nodes are hierarchically structured. In this article, the authors propose a TBFC for a General Process (TBFCG) model to recover from the faults of fog nodes. If a node gets faulty, the child nodes are disconnected. The authors propose Minimum Energy in the TBFCG tree (MET) and selecting Multiple Parents for recovery in the TBFCG tree (MPT) algorithms to select a new parent node for the disconnected nodes. A new parent node has to process data from not only the disconnected nodes, but also its own child nodes. In the evaluation, the energy consumption and execution time of a new parent node can be reduced by the proposed algorithms.

In the Internet of Things (IoT), not only computers like servers but also devices with sensor and actuator devices are interconnected. It is critical to make the IoT secure, especially devices. In the capability-based access control (CapBAC) model proposed to make IoT devices secure, an owner of each device issues a capability token, i.e. a set of access rights, to a subject. Only a subject holding the capability token is allowed to manipulate the device. However, a subject may get data in a device d1 via another device d2 although the subject holds no capability token to get data from the device d1. Here, the data in the device d1 illegally flow to the subject. In this article, the authors propose the operation interruption (OI) protocol where illegal get operations are interrupted. In the evaluation, the ratio of the number of get operations interrupted to the total number of get operations is kept constant even if the numbers of subjects and access rights granted to each subject increase in the OI protocol.