A designated Server Identity-based Encryption Scheme with Bidirectional Keyword Search
Jinghui Lv, Ruihan Dong, Xin Yang, Chenyang Jia · 2024
In the traditional encrypted email system, only the email receiver is allowed to use the private key to search the encrypted keywords, but bidirectional keyword search is not supported. In addition, it is unable to resist offline keyword guessing attacks(KGA) from internal adversaries and hides users' search patterns. In order to solve these problems, this paper proposes a designated-server public-key encryption scheme with bidirectional keyword search(ds-PEBKS) for encrypt emails. The scheme allows the sender and the receiver to search for encrypted keywords, combined with the designated server and enable the data owner authenticates the email information during encryption, ensuring that any adversary including the email server can not initiate offline KGA. Based on the decisional bilinear Diffie-Hellman assumption and the decisional Diffie-Hellman assumption, it is proved that the scheme satisfies the multi-ciphertext indistinguishability and multi-trapdoor privacy under the random oracle model. Compared with other related schemes in the aspects of function characteristics, calculation cost and communication cost and the results show that the computational efficiency of the ciphertext and trapdoor generation phase is of this scheme is more efficient and secure.