Efficient cloud-assisted revocable identity-based broadcast encryption in IoT

While the Internet of Things (IoT) has greatly facilitated our daily lives, this trend has encountered numerous security challenges in data storing and sharing especially for sensitive personal data. Identity-Based Broadcast Encryption (IBBE) is an efficient cryptographic technique to securely share messages among multiple users. Nevertheless, to prevent access by users who were previously authorized but now lack permission, user revocation should be integrated into IBBE. Despite several previous Revocable Identity-Based Broadcast Encryption (RIBBE) schemes were proposed, they are not practical for resource-constrained IoT devices due to their high computational cost during encryption and decryption, as well as the significant storage needs for the revocation list. To tackle these issues, we propose an outsourced RIBBE scheme that is appropriate for resource-constrained IoT devices. It not only effectively implements user revocation but also leverages a cloud server to handle complex calculations. Additionally, our scheme is designed to resist collusion attacks, enhancing overall security. Performance evaluation describes the great practicality and efficiency of our scheme.