Authors: Aatheni U, Dr. M. M. Janeela Theresa
Abstract: – Collaborative searchable encryption for group data sharing enables authorized users to jointly generate trapdoors and retrieve encrypted data without compromising privacy. However, existing solutions remain vulnerable to keyword guessing attacks (KGAs) by malicious insiders and subversion threats such as backdoors from untrusted hardware or software vendors. To overcome these security challenges, we propose a Privacy- Preserving Collaborative Searchable Encryption (PCSE) scheme using the BLAKE3 hash function. PCSE introduces a dedicated keyword server to enable server-derived keywords that resist insider KGAs, and employs cryptographic reverse firewalls to mitigate subversion risks. A distributed, multi-server keyword architecture is adopted to prevent single-point failures. The system also supports multi-keyword search, result verification, and includes a rate-limiting mechanism to restrict brute-force attempts. Formal analysis confirms resistance against KGAs and subversion attacks. Empirical evaluations demonstrate that PCSE achieves strong privacy, scalability, and efficient keyword-based search, making it suitable for secure cloud-based group data sharing
DOI: https://doi.org/10.5281/zenodo.15847524
