With the development of the Internet of Things (IoT) field, more and more data are generated by IoT devices and transferred over the network. However, a large amount of IoT data is sensitive, and the leakage of such data is a privacy breach. The security of sensitive IoT data is a big issue, as the data is shared over an insecure network channel. Current solutions include symmetric encryption and access controls to secure the data transfer, but they have some drawbacks such as a single point of failure. Blockchain is a promising distributed ledger technology that can prevent the malicious tampering of data, offering reliable data storage. This paper proposes a distributed access control system based on blockchain technology to secure IoT data. The proposed mechanism is based on fog computing and the concept of the alliance chain. This method uses mixed linear and nonlinear spatiotemporal chaotic systems (MLNCML) and the least significant bit (LSB) to encrypt the IoT data on an edge node and then upload the encrypted data to the cloud. The proposed mechanism can solve the problem of a single point of failure of access control by providing the dynamic and fine-grained access control for IoT data. The experimental results of this method demonstrated that it can protect the privacy of IoT data efficiently.

Searchable symmetric encryption (SSE) provides an effective way to search encrypted data stored on untrusted servers. When the server is not trusted, it is indispensable to verify the results returned by it. However, the existing SSE schemes either lack fairness in the verification of search results, or do not support the verification of multiple keywords. To address this, we designed a multi-keyword verifiable searchable symmetric encryption scheme based on blockchain, which provides an efficient multi-keyword search and fair verification of search results. We utilized bitmap to build a search index in order to improve search efficiency, and used blockchain to ensure fair verification of search results. The bitmap and hash function are combined to realize lightweight multi-keyword search result verification, compared with the existing verification schemes using public key cryptography primitives, our scheme reduces the verification time and improves the verification efficiency. In addition, our scheme supports the dynamic update of files and realizes the forward security in update. Finally, formal security analysis proves that our scheme is secure against Chosen-Keyword Attacks (CKA), experimental analysis demonstrations that our scheme is efficient and viable in practice.

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With the recent development in network technology over a few years, digital works can be easily published online. One of the main issues in the field of digital technology is the infringement of digital works, which can seriously damage the data owners’ rights and affects the enthusiasm of the owners to create original work. Thus, more attention is required for the protection of digital copyright as it has a great impact on the development of society. Many digital copyright protection techniques were developed in the past, but still, there are many loopholes in the protection systems to be covered. The protection means are still relatively weak, timeliness is poor, infringement is frequent, a right determination is cumbersome, and the results are not ideal. Aiming at the mentioned problems, this paper proposes a protection technique, which can realize the automatic management of the complete digital rights life cycle on the blockchain using fabric's smart contract technology. The proposed system is based on blockchain technology, which leverages the distributed, tamper-proof and traceable characteristics of blockchain. The system uses smart contracts to manage the full life cycle of digital copyright. The test results show that the proposed system provides effective protection of the digital copyright system and can efficiently confirm the rights of digital copyright.

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