基于区块链的高透明度PKI认证协议

公钥基础设施（PKI）作为互联网空间安全基础设施的重要组成部分，为互联网的信息传输提供必要的真实性、完整性、机密性和不可否认性。现有的公钥基础设施存在证书颁发机构权力过大、吊销查询困难等问题。随着区块链技术的发展，可以利用区块链技术去中心化、透明度高、结构扁平等优点来解决上述公钥基础设施存在的问题，提高整个互联网建立信任关系的能力和效率。因此，提出基于区块链的高透明度PKI认证协议。该协议通过加入门限签名技术提出了改进的实用拜占庭容错共识算法（TS-PBFT）。TS-PBFT算法降低了原有实用拜占庭容错（PBFT，practical Byzantine fault tolerance）共识算法的通信复杂度，减少了通信开销；TS-PBFT 算法在视图切换协议的主节点选举引入了外界监督机制，增加了可监管性；TS-PBFT 算法在快速一致性协议中引入了批处理机制，提升了共识过程的性能。该协议一方面在提出的PBFT 算法的基础上引入了区块链技术，提升了证书吊销查询的安全性，并引入了计数布隆过滤器，提升了证书查询的效率；另一方面，该协议在证书的生命周期管理中增加了证书审计流程，对证书颁发机构的行为做出监管，促使其提高安全标准，达到限制其权力的目的。安全性分析和效率实验分析表明，所提协议系统具有抵抗伪装申请证书攻击等安全属性，与已有PKI协议相比在TLS/SSL握手耗时上具有优势。

Blockchain-based high transparent PKI authentication protocol

The public key infrastructure (PKI), as an significant component of the current Internet security infrastructure, guarantees the information transmission with the necessary authenticity, integrity, confidentiality and non-repudiation.However, the existing PKI also has shortcomings of excessive power of certification authority and difficulties in revoking and querying.Blockchain can be used to solve those problems by leveraging its advantages, such as decentralization, high transparency and flat structure.Furthermore, the ability and efficiency of the entire Internet to establish trust relationships may be improved.The transparent public key infrastructure (PKI) certification protocol based on the blockchain was proposed.The TS-PBFT algorithm was designed in the proposed protocol by adopting the threshold signature technology to the Practical Byzantine fault tolerance (PBFT) algorithm.The TS-PBFT algorithm reduced the communication overhead via reducing the communication complexity, strengthened the supervision via introducing external monitoring mechanism in the master node election of the view change protocol, and also improved the performance of the consensus mechanism via adding a batch processing mechanism.Moreover, a transparent blockchain-based PKI certification protocol was designed.The proposed protocol increased the security of certificate revocation and query, it also improved the efficiency of the certificate query by the introduction of counting bloom filters.Besides, the proposed protocol added audit function into the certificate lifecycle management.Accordingly, it can supervise the behavior of the certificate authority (CA), prompt it to improve security standards, and then achieve the purpose of limiting its authority.According to the security analysis and efficiency experiments, the proposed protocol was equipped with security properties, such as the resistance to spoofing certificate application attacks, and it achieved the best performance on TLS/SSL handshake time compared with existing PKI protocols.