Revocable Attribute-Based Signature for Blockchain-Based Healthcare System

Blockchain-Based Healthcare System (HS-BC) is an electronic medical record (EMR) data-sharing system, which significantly facilitates the storage, access, and sharing of EMR data, and provides patients with timely and effective medical diagnosis and treatment. However, due to the high openness of the blockchain, security and privacy still are major concerns in HS-BC. In this paper, we propose an attribute-based signature scheme with attribute revocation to protect the privacy of the user's identity in HS-BC. Under the premise of using attributes to identify users and protect their identity, the user combines the attribute master-key and the attribute update-key to calculate the attribute signing key, where the attribute master-key is related to the user identity and attribute set, and the attribute update-key is related to the attribute revocation. Through making use of the KUNodes algorithm, attribute revocation can effectively achieve. The designed attribute-based signature scheme requires relatively few pairing operations and does not rely on a central authority. Besides, we formally conducted a security analysis and proved that the proposed scheme is unforgeable, collusion resistant and privacy-preserving. Finally, we evaluate the proposed attribute-based signature scheme in terms of storage and efficiency. Comparison and experimental results show that it is feasible.