An Efficient Multi-Show Unlinkable Attribute Based Credential Scheme for a Collaborative E-Health Environment

Modern electronic healthcare (e-health) systems constitute collaborative environments in which patients' private health data are shared across multiple domains. In such environments, patients' privacy can be violated through the linkability of different user access sessions over patient health data. Therefore, enforcing anonymous as well as multi-session unlinkable access for the users in e-health systems is of paramount importance. As a way of achieving this requirement, more emphasis has been given to anonymous attribute credentials, which allows a user to anonymously prove the ownership of a set of attributes to a verifier and thereby gain access to protected resources. Among the existing well known credential schemes, the U-Prove does not provide unlinkability across multiple user sessions whereas Idemix provides it with a significant computational overhead. As a solution, we propose a novel, anonymous attribute based credential scheme with multi-session unlinkability. The simulation results and complexity analysis show that the proposed scheme achieves the aforementioned property with substantially lower computational overhead compared to the existing credential schemes with multi-session unlinkability. Finally, we present how the proposed credential scheme can be applied to a collaborative e-health environment to provide its users with the anonymous and unlinkable access.