Common use of Authentication Phase Clause in Contracts

Authentication Phase. The authentication phase aims to mutually authenticate both of the sensor nodes and the remote user. To communicate the health-related data to the remote user, each sensor must execute the authentication process. The proposed scheme supports two cases of sensors authentication. The first case when the sensor nodes are not in the same location as the remote user, and in the second case, they are in the same location. The proposed authentication and key agreement scheme is as follows (see Figure 3): The sensor node initiates the authentication phase, it generates a random nonce N on 8 bytes and sends a message composed of the generated nonce N, its masked identity MSIdi, and a h(MSIdi, N, Idi) to the remote user. Upon receiving the message by the remote user, the message is verified by checking whether received hash is equal to the computed hash. If the matching is successful, the remote user generates a random nonce M on 8 bytes, else it is an authentication failure. The remote user checks the location of the sensor node. If the remote user cannot reach the sensor node in his Wi-Fi covered area, then: Case ‘not in the area’: The remote user transmits to the gateway node a message composed by the masked identity of the sensor node MSIdi, the received nonce N, the nonce M, and a h(MSIdi, N, M). Upon receiving the message by the gateway node, it verifies the message by checking whether the received hash is equal to the computed hash. If the check is successful, the gateway node generates a random nonce S on 8 bytes, and applies an XOR with the received nonce N: (T = N S). Then, it sends to the remote user a message composed of the received nonces N and M, the computed value T and a h(M, ▇▇▇, S), otherwise the authentication fails. When the remote user receives the message, the nonce value S is computed as follows: (S = N T) and the message is verified by checking whether the received hash is equal to the computed hash. If the check is successful, the remote user also generates a random nonce W on 8 bytes, applies an XOR with value S as: