Paper 2024/394 Original: eprint.iacr.org/2024/394 ↗

A Deniably Authenticated Searchable Public Key Encryption Scheme in Mobile Electronic Mail System

Abstract

Confidentiality and authentication are two main security goals in secure electronic mail (e-mail). Furthermore, deniability is also a significant security property for some e-mail applications to protect the privacy of the sender. Although searchable encryption solves the keyword searching problem in a secure e-mail system, it also breaks the deniability of the system. Because the adversary can obtain the information of the data sender and data user from the trapdoor as well as ciphertext used for keyword searching. At the same time, efficiency is another problem in mobile computing. To overcome the issues, we put forward deniably authenticated searchable public key encryption (DA-SPKE) which can apply to the deniable e-mail system. We first define the DA-SPKE model and propose the DA-SPKE scheme. Then we prove its security in the random oracle model and evaluate its efficiency. Finally, we use it in a deniably secure e-mail system to protect both data senders’ and data users' privacy.