Protecting Medical Image Privacy by Using Chaos Encryption and Blockchain

Remote healthcare enables the delivery of diagnostic and treatment services to patients, particularly in areas with limited access to medical resources. However, such systems are vulnerable to attacks such as interception and tampering during medical image transmission and storage. In this paper, we propose a framework for protecting medical image privacy by using chaos encryption and blockchain technology. Secret keys are encrypted and stored in blockchain transactions, leveraging blockchain’s immutability and asymmetric encryption for user authorization. Additionally, the hash values of medical images and their metadata are recorded on the blockchain to enable integrity verification of decrypted images, preventing tampering with critical details. Furthermore, we propose a secure and fast image encryption scheme. We design a pseudorandom number generation algorithm based on two chaos maps to dynamically update the base key, providing a secure key stream correlated with the plaintext image. Based on a confusion-diffusion structure, our scheme employs parallel encryption to meet real-time medical data processing requirements in practical applications. The bidirectional ciphertext feedback mechanism is introduced to achieve the avalanche effect. Finally, we conduct comprehensive security analyses and performance evaluations on the proposed encryption scheme. The results demonstrate its superior performance in both security and efficiency.