LAUSR

In the Internet of Things (IoT), a cyber physical system (CPS) has achieved great success in a wide range of distributed integration environments. In the cyber physical system (CPS), interconnected sensing devices collect data in the surrounding environment and send data to all interested nodes through the network, thereby sharing all nodes data. This process can be implemented by using a publish/subscribe (pub/sub for short) system. Providing the basic security mechanisms such as authorization and confidentiality is a challenge due to the loose coupling of subscribers and publishers in such a pub/sub system. At the meanwhile, the existing IoT ecosystem mostly relies on a centralized server and thus faces the problem of single point failure. Thus, it is interesting to realize a brokerless or decentralized pub/sub model. Inspired by this motivation, this paper mainly proposes a privacy-preserving publish/subscribe model by using the blockchain technique, which evades the centralized trustroot setting and the problem of single point failure. Another key point of our proposal is that the primitive of public key encryption with equality test (PKEwET) is employed to enable all the required authorization, communication and topics matching can be finished in a confidential manner. Finally, a lightweight prototype of our proposal is implemented by using web3j, and the security and efficiency analysis are also presented.