Blockchain-Empowered Search Over Encrypted Data With Forward and Backward Privacy

Blockchain-Empowered Search Over Encrypted Data With Forward and Backward Privacy

연구 분야: Infrastructure

학회: BSCI '23: Proceedings of the 5th ACM International Symposium on Blockchain and Secure Critical Infrastructure

With the development of cloud data, searchable encryption has been getting more attention. Searchable encryption with forward and backward privacy can better meet people’s security needs, for it leaks less information. However, only forward and backward is not enough to deal with the situation where the server returns less search results than it should. This paper will focus on this question. Since the consensus mechanism in the blockchain can well ensure honesty, this paper proposes a symmetric searchable encryption with forward and backward privacy based on blockchain smart contracts. We propose a one-to-one scheme SCSSEFB that can be easily extended to one-to-many and extended to the asymmetric case. According to our calculations and evaluations, this scheme has O(n · m) + O(s) + O(s · log2(s)) time update overhead and O(m) + O(m · log2(s′)) search time overhead, where n keywords are updated each time on average, each w corresponds to m identifiers, s documents are updated each time, and a total of s′ documents when searching. Specifically, our scheme takes 103 seconds in the update phase when the test data set is 16,000 bytes and the amount of keyword pairs is 50, and 142.5 seconds in the search phase when the number of keywords is 5 and the amount of leaves in the Merkle tree is 8388608.