Certificateless authenticated key agreement for blockchain-based WBANs

Authenticated key agreement (AKA) enables communicating parties to mutually establish a session key, in a way that each entity is assured of the authentication of its peer. Certificateless AKA (CLAKA) protocols are widely designed since they avoid the key escrow problem found in identity-based systems and overcome certificateless management overheads in Public Key Infrastructure (PKI). Furthermore, the existing CLAKA were designed to operate in centralized network. Such architecture is a single point of management and single point of failure. We need lightweight protocols that fit with body sensors capabilities. In order to mitigate the aforementioned vulnerabilities, we propose a pairing-based certificateless against the key escrow problem. Our protocol operates in a decentralized system against the single point of failure and management. The protocol establishes a session key in the first phase for communications. The ring signature is used in the second phase for node authentication. The ring signature has advantage of reducing computation costs where a node signs a signature on behalf of others. The signing node remains anonymous and other nodes can verify the signature. Another advantage of ring signature is that there is no specification about the size of the group.