Multi-recipient Public-Key Authenticated Encryption with Keyword Search

In cloud computing, private data is usually encrypted and uploaded to a cloud server, which is possibly available to multiple recipients. The traditional schemes fail to account for scenarios with multiple recipients, resulting in low encryption efficiency. In order to better accommodate the multi-recipient scenario, multi-recipient public key authenticated encryption with keyword search (MR-PAEKS) was developed. However, the security of existing MR-PAEKS schemes is not sufficiently secure as they are susceptible to multi-choice ciphertext attacks and multi-choice trapdoor attacks. In order to improve the security of MR-PAEKS in the literature, this paper proposes the first multi-recipient public key authenticated encryption with keyword search scheme satisfying the securities of fully multi-ciphertext indistinguishability (Fully MCI) and fully multi-trapdoor indistinguishability (Fully MTI), and proves its security within the standard model. Compared with related work, our scheme achieves significant improvements in security at the cost of a slight reduction in efficiency.