Dual-Server Public-Key Authenticated Searchable Encryption With Constant Trapdoor Against Inside Keyword Guessing Attacks

Public key authenticated encryption with keyword search (PAEKS) is an advanced asymmetric searchable encryption technique that provides strong resistance against inside keyword guessing attacks (KGAs). However, most PAEKS schemes are limited to one-to-one search, resulting in a linear increase in the number of trapdoors as the number of senders grows. Some solutions have been introduced, but they are still deficient in security or privacy. In this paper, we propose a novel dual-server public key authenticated searchable encryption scheme with constant trapdoor. The proposed scheme achieves robust security against inside KGAs even if a malicious server is allowed to collude with certain data senders. Meanwhile, in contrast to existing schemes, it prevents the leakage of keyword equivalence among unretrieved ciphertexts. Moreover, the data receiver in our system only needs to create one trapdoor per keyword to search for their ciphertexts produced by different data senders, which is not achievable in most prior works. The experimental results demonstrate that our proposed construction maintains comparable performance to existing solutions, especially in multi-sender scenarios.