4S: A secure and privacy-preserving key management scheme for cloud-assisted wireless body area network in m-healthcare social networks

Cloud-assisted wireless body area networks (WBANs) significantly facilitate efficient patient treatment of high quality, unfortunately in the meanwhile greatly challenge the patient's data confidentiality and privacy. The existing work mainly focused on the traditional scenario where patients securely stay indoors. In this paper, we consider a more practical situation of cloud-assisted WBANs in m-healthcare social networks where patients traverse among blocks outdoors and WBANs are more vulnerable to sophisticated attacks including even node compromise attack. To solve the problem, a secure and privacy-preserving key management scheme resilient to both time-based and location-based mobile attacks is proposed by the cooperation of the mobile patients in the same social group for both hierarchical and distributed environment. It also protects patient's identity privacy, sensor deployment privacy and location privacy by exploiting the blinding technique and embedding human body's symmetric structure into Blom's symmetric key mechanism with modified proactive secret sharing. Especially, the computationally-intensive privacy-preserving key material updating is outsourced to the cloud server and the unchanged pairwise keys after key material updating dramatically saves the resources for energy-constrained WBANs. Finally, the security analysis and simulation results show our scheme far outperforms the previous ones in terms of resisting mobile attacks and storage, computation and communication overhead.