Consensus algorithm for medical data storage and sharing based on master–slave multi-chain of alliance chain

The safe storage and sharing of medical data have promoted the development of the public medical field.At the same time,blockchain technology guarantees the safe storage and sharing of medical data.However,the consensus algorithm in the current medical blockchain cannot meet the requirements of low delay and high throughput in the large-scale network,and the identity of the primary node is exposed and vulnerable to attack.Therefore,this paper proposes an efficient consensus algorithm for medical data storage and sharing based on a master–slave multi-chain of alliance chain(ECA_MDSS).Firstly,institutional nodes in the healthcare alliance chain are clustered according to geographical location and medical system structure to form a multi-zones network.The system adopts master–slave multi-chain architecture to ensure security,and each zone processes transactions in parallel to improve consensus efficiency.Secondly,the aggregation signature is used to improve the practical Byzantine fault-tolerant(PBFT)consensus to reduce the communication interaction of consensus in each zone.Finally,an efficient ring signature is used to ensure the anonymity and privacy of the primary node in each zone and to prevent adaptive attacks.Meanwhile,a trust model is introduced to evaluate the trust degree of the node to reduce the evil done by malicious nodes.The experimental results show that ECA_MDSS can effectively reduce communication overhead and consensus delay,improve transaction throughput,and enhance system scalability.

Cross-domain identity authentication scheme based on blockchain and PKI system

In vehicular ad hoc networks(VANET),the cross-domain identity authentication of users is very important for the development of VANET due to the large cross-domain mobility of vehicle users.The Public Key Infrastructure(PKI)system is often used to solve the identity authentication and security trust problems faced by VANET.However,the PKI system has challenges such as too centralized Authority of Certification Authority(CA),frequent cross-domain access to certificate interactions and high authentication volume,leading to high certificate management costs,complex cross-domain authentication paths,easy privacy leakage,and overburdened networks.To address these problems,this paper proposes a lightweight blockchain-based PKI identity management and authentication architecture that uses smart contracts to reduce the heavy burden caused by CAs directly managing the life cycle of digital certificates.On this basis,a trust chain based on smart contracts is designed to replace the traditional CA trust chain to meet the general cross-domain requirements,to effectively avoid the communication pressure caused by a mass of certificate transmissions.For the cross-domain scenario with higher privacy and security requirements the identity attribute authentication service is provided directly while protecting privacy by using the Merkle tree to anchor identity attribute data on and off the blockchain chain.Finally,the proposed scheme was comprehensively analyzed in terms of cost,time consumption and security.