With the rapid development of physical networks, tens of billions of Internet of Things (IoT) devices have been deployed worldwide. Access control is essential in the IoT system, which manages user access to vital IoT data. However, access control for the IoT is mainly based on centralized trusted servers, which face problems such as a single point of failure and data leakage. To tackle these challenges, we propose an access control framework for the IoT by combining blockchain and Intel software guard extension (SGX) technology. A blockchain validates both IoT devices and edge servers added to the network. The access control contract is deployed on the blockchain, which can manage attribute-based access control policies in a fine-grained manner and make access control decisions flexibly. SGX technology is introduced into the edge computing server to realize the confidentiality of data processing. Finally, we implemented the prototype of the framework on Quorum and conducted extensive experiments and theoretical analyses on the performance of the blockchain. The results of the experimental tests and theoretical analyses show that our framework has more advantages in computing costs and on-chain storage costs.

Searchable encryption enables users to enjoy search services while protecting the security and privacy of their outsourced data. Blockchain-enabled searchable encryption delivers the computing processes that are executed on the server to the decentralized and transparent blockchain system, which eliminates the potential threat of malicious servers invading data. Recently, although some of the blockchain-enabled searchable encryption schemes realized that users can search freely and verify search results, unfortunately, these schemes were inefficient and costly. Motivated by this, we proposed an improved scheme that supports fine-grained access control and flexible searchable encryption. In our framework, the data owner uploads ciphertext documents and symmetric keys to cloud database and optional KMS, respectively, and manipulates the access control process and searchable encryption process through smart contracts. Finally, the experimental comparison conducted on a private Ethereum network proved the superiority of our scheme.

The introduction of knowledge graph technology in the field of network security can enable network security personnel to better grasp the network security situation, detect network attacks, analyze and determine the network attack chain, and then take targeted preventive measures to continuously improve the security of network space. This paper proposes a method of constructing knowledge graph based on network security domain ontology. Aiming at the multi-source heterogeneous network security data, extracting the association relation and designing the network security domain ontology model. Through knowledge extraction of massive structured, semi-structured and unstructured data, the network security domain knowledge graph is constructed according to the top-down construction method, and the knowledge is stored, displayed and queried through the Neo4j graph database. The constructed domain knowledge graph implements association analysis of multi-source heterogeneous data from six dimensions of network security-related, including asset dimension, attack dimension, vulnerability dimension, weakness dimension and alarm dimension, laying a foundation for network attack analysis and detection.