Paper 2026/970

Security Analysis on a Blockchain-based Public-Key Authenticated Searchable Encryption Scheme

Abstract

Du et al. (Security and Communication Networks, 2022) proposed a public-key authenticated searchable encryption scheme that employs Bloom filters and blockchain. In their scheme, Bloom filters are used to search encrypted keywords, while blockchain is used to guarantee the correctness of search results. In this paper, we demonstrate that Du et al.'s scheme leaks keyword information from ciphertexts. Our analysis focuses on the fact that the Bloom filter embedded in a ciphertext is uniquely determined by the Diffie-Hallman key and the keyword to be encrypted and is directly included in the ciphertext. We show that the success probability of the proposed attack is lower bounded by the probability that no false positives occur in the Bloom filter, and we evaluate this probability to confirm that the attack achieves a sufficiently high success rate. Furthermore, we examine Du et al.'s security model and their assumed usage scenarios, and discuss the validity of our attack under those conditions. We also consider a simple modification intended to prevent our attack and demonstrate that a slightly adapted version of the attack remains effective against the modified scheme. In addition, we show that previously generated ciphertexts can still pass verification even when the search results differ, indicating that the blockchain-based integrity verification mechanism is insufficient.