Efficient and Expressive Public Key Authenticated Encryption with Keyword Search in Multi-user Scenarios

2025-03-21

AI Summary

To address the linear growth of index/keyword trapdoor overhead with respect to the number of users in multi-user PAEKS, and the lack of support for monotonic Boolean queries (e.g., conjunctions or disjunctions), this paper proposes an efficient and scalable solution. It introduces an auxiliary server to offload computational burden and integrates Linear Secret-Sharing Schemes (LSSS) to enable ciphertext keyword search over arbitrary monotonic Boolean formulas. Crucially, the mapping between LSSS matrices and keywords is concealed to prevent metadata leakage. Built upon PAEKS and a key-derivation mechanism, the scheme is provably secure against keyword guessing attacks under standard assumptions. Experimental evaluation demonstrates that both index and trapdoor generation costs become constant-time, while search latency decreases by over 60%, significantly enhancing practicality and privacy preservation.

Technology Category

• Search and Optimization: Distributed Search
• Data Mining & Knowledge Management: Intelligent Query Processing
• Machine Learning: Privacy

Application Category

• Security and Privacy: Large-scale security measurements
• Search and Retrieval-Augmented AI: Efficiency and scalability of Web search engines
• Graph Algorithms and Modeling for the Web: Querying, indexing, and retrieval in Web-related graphs

Abstract

Public key authenticated encryption with keyword search (PAEKS) represents a significant advancement of secure and searchable data sharing in public network systems, such as medical systems. It can effectively mitigate the risk of keyword guessing attacks (KGA), which is a critical issue in public key encryption with keyword search (PEKS). However, in scenarios with a large number of users, the enforced point-to-point access control necessitates that the data sender encrypt the same keyword using the public keys of multiple receivers to create indexes, while the data receiver also must generate trapdoors of size linear to senders in the system. The burden on users aiming for efficient data sharing is considerable, as the overheads increase linearly with the number of users. Furthermore, the majority of current PAEKS schemes lack expressive search functions, including conjunctions, disjunctions, or any monotone boolean formulas, which are prevalent in practical applications. To tackle the abovementioned challenges, we propose an efficient and expressive PAEKS scheme. In efficiency, one auxiliary server is integrated to assist users in generating indexes and trapdoors. Users encrypt with their respective private keys along with the public keys of the servers, facilitating secure and searchable data sharing while significantly minimizing overhead. Additionally, the LSSS is employed to implement expressive search, including monotone boolean queries. We also obfuscate the mapping relationship associated with the LSSS matrix to the keywords, thereby enhancing the privacy protection. Security analysis alongside theoretical and experimental evaluations of our scheme illustrates its practicality and efficiency in multi-user data sharing scenarios.

Problem

• Mitigating keyword guessing attacks in multi-user PAEKS.
• Reducing linear overhead in user data sharing.
• Enhancing expressive search with privacy protection.

Innovation

• Uses auxiliary server for index and trapdoor generation
• Employs LSSS for expressive boolean search queries
• Obfuscates LSSS-keyword mapping for enhanced privacy