A Secure Signcryption Scheme for Electronic Health Records Sharing in Blockchain

In the existing Electronic Health Records (EHRs), the medical information of patients is completely controlled by various medical institutions. As such, patients have no dominant power over their own EHRs. These personal data are not only inconvenient to access and share, but are also prone to cause privacy disclosure. The blockchain technology provides a new development direction in the medical field. Blockchain-based EHRs are characterized by decentralization, openness and non-tampering of records, which enable patients to better manage their own EHRs. In order to better protect the privacy of patients, only designated receivers can access EHRs, and receivers can authenticate the sharer to ensure that the EHRs are real and effective. In this study, we propose an identity-based signcryption scheme with multiple authorities for multiple receivers, which can resist N-1 collusion attacks among N authorities. In addition, the identity information of receivers is anonymous, so the relationship between them and the sharer is not disclosed. Under the random oracle model, it was proved that our scheme was secure and met the unforgeability and confidentiality requirements of signcryption. Moreover, we evaluated the performance of the scheme and found that it had the moderate signcryption efficiency and excellent signcryption attributes.