Blockchain technology, known for its decentralized and tamper-resistant nature, offers strong auditing guarantees across a wide range of applications. However, its inherent immutability presents challenges when correcting erroneous transactions or removing sensitive information is necessary. To address this, the concept of redactable blockchain has emerged, aiming to improve adaptability to real-world regulatory and operational needs. Yet, existing designs often suffer from limitations in decentralization, security, or efficiency. This paper introduces an Enhanced Threshold Chameleon Hash (ETCH) scheme as a foundational building block for redactable blockchains. ETCH enables redactions only when a predefined threshold of nodes collaborates to generate trapdoor shares, preserving decentralization. It also enhances collision resistance, overcoming key security flaws in prior schemes, and incorporates a periodic trapdoor refresh mechanism to improve long-term robustness. Experimental results show that ETCH reduces computational overhead by 50% in Hash and Verify phases and by 22.26% in the Adapt phase. The prototype implementation of the ETCH-based redactable blockchain further confirms ETCH's effectiveness in supporting low-latency redactions and mitigating blockchain state growth. Overall, ETCH improves both the security and efficiency of redactable blockchains, broadening their applicability in privacy-sensitive and regulated scenarios.

Summary Compared with traditional voting methods, electronic voting can effectively avoid the phenomenon of fraud for personal gains in various links, it is faster and more accurate in the tallying stage. However, many electronic voting systems have many problems such as inability to verify ballots, easy to be forged, and low computing efficiency. We propose an electronic voting protocol based on homomorphic signcryption and blockchain. The protocol makes the voting process public through blockchain and replaces the traditional trusted third party with the smart contract. It uses the homomorphic encryption algorithm and the homomorphic signcryption algorithm to encrypt and sign the ballot and uses their aggregation properties to perform homomorphic tally on the encrypted votes. This not only reduces the excessive burden on the voters but also improves the voting efficiency. At the same time, it can satisfy the security of electronic voting, and the amount of calculation is small, so it is more convenient and flexible to use in large‐scale voting.

With the maturity of Internet-of-Things technology, location-based service (LBS) is developing rapidly in intelligent terminal devices, and it brings new vitality to the fields of logistics, transportation, product traceability and so on. The popularity of LBS produces a lot of spatial data, which inevitably brings burden to the storage and management of LBS provider (LBSP). With the help of cloud computing and cloud storage, outsourcing spatial data to cloud server has become a new trend. However, due to the cloud server is not trusted, data outsourcing will face the problems of data disclosure and query disclosure. Range query is a common query in LBS, considering the situation of data outsourcing, this article proposes an accurate range query (ARQ) scheme, which can realize efficient range query while preserving LBSP's data privacy and user's query privacy from being disclosed to the cloud server. The ARQ scheme is suitable for spatial data in any form without being limited to the case that the data points are only integers, which has a certain practical significance. In addition, by dividing the region into atomic regions, ARQ can realize sublinear search time and ensure dynamic update of spatial data. We proved the security of the proposed scheme through security analysis, and demonstrated the effectiveness of the scheme through experiments.

More and more users are uploading their data to the cloud without storing any copies locally. Under the premise that cloud users cannot fully trust cloud service providers, how to ensure the integrity of users’ shared data in the cloud storage environment is one of the current research hotspots. In this paper, we propose a secure and effective data sharing scheme for dynamic user groups. (1) In order to realize the user identity tracking and the addition and deletion of dynamic group users, we add a new role called Rights Distribution Center (RDC) in our scheme. (2) To protect the privacy of user identity, when performing third party audit to verify data integrity, it is not possible to determine which user is a specific user. Therefore, the fairness of the audit can be promoted. (3) Define a new integrity audit model for shared cloud data. In this scheme, the user sends the encrypted data to the cloud and the data tag to the Rights Distribution Center (RDC) by using data blindness technology. Finally, we prove the security of the scheme through provable security theory. In addition, the experimental data shows that our proposed scheme is more efficient and scalable than the state-of-the-art solution.