Efficient and secure heterogeneous online/offline signcryption for wireless body area network

As a special Internet of Things (IoT) application, the wireless body area network (WBAN) has gained widespread attention by medical institutions. However, existing schemes for WBAN data transmission lack heterogeneity support across certificateless cryptosystem (CLC) and public key infrastructure (PKI), resulting in issues like key escrow or complicated certificate management. In addition, for performance reasons, conventional signcryption protocols are unsuitable for WBAN applications. To address these gaps and enable secure and efficient sensitive data transmission from WBAN sensors to hospital servers, we design a heterogeneous online/offline signcryption scheme. Our scheme enables patients' sensors implanted or worn to encrypt sensitive data in CLC and send it to the hospital server in PKI system. The CLC avoids key escrow issue while the PKI increases scalability. We minimize the online computational cost of WBAN sensors by dividing signcryption into offline and online phases, with time-consuming operations in the offline phase. Furthermore, we formally prove the security of our scheme and evaluate its performance. Results show our scheme has advantages in supporting heterogeneity across CLC and PKI with low computational costs, making it uniquely suitable for the protection of data privacy in WBAN applications compared to existing protocols.