Deniably authenticated searchable encryption scheme based on Blockchain for medical image data sharing

In the cloud applications of medical data based on blockchain, doctors and managers usually want to obtain image data shared by other healthcare institutions. To ensure the privacy and workability of the image data, it is necessary to encrypt plain image data, retrieve cypher data and verify the authenticity of the data. Public key authenticated searchable encryption (PAEKS) is an effective mechanism to realize the privacy and workability properties of data. However, the existing PAEKS schemes are unable to realize the identity privacy protection of the data owner, and the traditional blockchain system (such as the Bitcoin) cannot achieve these goals directly. To overcome the above drawback, we first present a deniably authenticated searchable encryption scheme for medical image data sharing (DASES) that is based on blockchain and deniably authenticated encryption technology. The DASES takes advantage of blockchain technology to ensure the non-tampered, unforgettable and traceability of the image data, and it also avoids the limitation of the blockchain's own storage and computing power. The DASES can not only withstand inside keyword guessing attack (IKGA) but also provide effective privacy protection and verify the authenticity of medical image data. Hence, it can better protect the privacy of data senders and provide stronger security. Next, we prove that the DASES satisfies the indistinguishability of the ciphertext and trapdoor. It is regrettable that the DASES is less efficient than related schemes in the literature, but its greatest strength is its ability to provide better identity privacy protection and stronger security.