Abstract: Low-power wide area network has the advantages of low power consumption and long distance, which has become a research hotspot. However, the system is not completely reliable in terms of efficiency and privacy due to the limited security capability of sensor nodes, easy aging and malicious nodes in low-power wide area network. Aiming at the above problems, this paper analyzes Lora’s media access control layer and proposes a set of ciphertext data audit algorithm. The efficiency of ciphertext data processing is accelerated by Bloom filter. In addition, the homomorphic encryption technology is used to realize effective ciphertext data range query function on the premise of data protection. Finally, the Blockchain technology is used to realize the traceability of communication data, so as to facilitate the follow-up of problem nodes. The analysis results show that the new scheme has high security performance and the communication efficiency can reach O(logn).

Key words: Internet of Things, Blockchain, privacy protection, traceability, dense calculation