Biblio

Problems related to privacy and cyber-attacks have increased in recent years as a result of the rapid development of cloud computing. This work concerns secure cloud computing services on a blockchain platform, called cloud@blockchain, which benefit from the anonymity and immutability of blockchain. Two functions- anonymous file sharing and inspections to find illegally uploaded files- on cloud@blockchain are designed. On cloud@blockchain, cloud users can access data through smart contracts, and recognize all users within the application layer. The performance of three architectures- a pure blockchain, a hybrid blockchain with cache and a traditional database in accessing data is analyzed. The results reveal the superiority of the hybrid blockchain with the cache over the pure blockchain and the traditional database, which it outperforms by 500% and 53.19%, respectively.

Public key infrastructure (PKI) is the foundation and core of network security construction. Blockchain (BC) has many technical characteristics, such as decentralization, impossibility of being tampered with and forged, which makes it have incomparable advantages in ensuring information credibility, security, traceability and other aspects of traditional technology. In this paper, a method of constructing PKI certificate system based on permissioned BC is proposed. The problems of multi-CA mutual trust, poor certificate configuration efficiency and single point failure in digital certificate system are solved by using the characteristics of BC distribution and non-tampering. At the same time, in order to solve the problem of identity privacy on BC, this paper proposes a privacy-aware PKI system based on permissioned BCs. This system is an anonymous digital certificate publishing scheme., which achieves the separation of user registration and authorization, and has the characteristics of anonymity and conditional traceability, so as to realize to protect user's identity privacy. The system meets the requirements of certificate security and anonymity, reduces the cost of CA construction, operation and maintenance in traditional PKI technology, and improves the efficiency of certificate application and configuration.