A Secure and Efficient Access Control Scheme for Shared IoT Devices over Blockchain

Figure 1

(a) System architecture of the proposed scheme. Note: This figure contains all the components in the scheme and their interactions. The green line with arrows indicates wireless communication. The green solid line indicates offline communication. The CA deploys and initializes the whole system. The user communicates with the shared devices through the gateways before being granted access and can communicate with the device directly after being authenticated. Because of limited communication capacity, the shared devices upload information to the blockchain through the gateway. (b) The access process of a user to a shared IoT device. Note: (1) When a user wants to access a shared IoT device, he/she searches for a special service item on the blockchain and makes the prepayment. (2) The user and nearest gateway node A authenticate each other using the proposed authentication protocol. (3) The gateway node checks whether the user has prepaid for the service item on the blockchain. (4) The gateway and the shared IoT device authenticate each other using the proposed authentication protocol. (5) The user transmits parameters to the smart contract, and the device transmits parameters through the gateway to complete the final step of the authentication. (6) The user sends a specific instruction in the form of ciphertext to the shared device, and the device decrypts it with the negotiation key. Then, the service starts. For example, in the scene of a shared car, it goes from place A to place B. When the user and shared device such as the shared car arrive at the destination near a new gateway node B, the user wants to end the use of the shared car. In order to prevent impersonation attacks and clearing the charge, they begin to authenticate each other. (7) The user and the new gateway do the mutual authentication. (8) The device authenticates the new gateway. (9) The user, the new gateway, and the device pass relevant parameters to the smart contract for settlement, and the service is ended.

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