Most IoT devices cannot afford to be a blockchain node due to the high computation and storage loads. Thus, the blockchain is usually deployed on one delegate node, e.g., the edge device or cloud, which may encounters three drawbacks: (1) The delegate node becomes the single failure point when the number of delegate notes are limited. (2) The delegate node replicating the blockchain data can lead to privacy information leak. (3) The delegate node is vulnerable to the Distributed Denial of Service (DDoS) attack. To tackle these drawbacks, we consider to minimize the redundant of blockchain to make the IoT devices as the specialized blockchain nodes. In this paper, we integrate a permissioned blockchain (HLF), an attribute-based access control (ABAC) and an identity-based signature (IBS) to build a security, lightweight, and cross-domain blockchain-based IoT access control system. Specifically, we divided the IoT system into different function domains, named IoT domains. Then, we establish a local blockchain ledger for each IoT domain to enable more IoT devices as blockchain nodes. The local blockchain ledger records the IoT domain entities' attributes, policy files' digests, and access decisions. Meanwhile, we use the channel technology of HLF to realize cross-domain access and use the IBS to filter the legal access requests for each IoT domain to prevent DDoS attacks. We also design a policy decision point (PDP) selection algorithm that select multiple IoT devices (blockchain nodes) to achieve the real-time distributed policy decisions (off-chain). Finally, we implement and evaluate the proposed system to demonstrate its practicality.

In a distributed system, cross-domain access control is an important mechanism to realize secure data sharing among multiple domains. Most of the existing cross-domain access control mechanisms are generally based on a single-server architecture, which has limitations in terms of security and reliability (the access decision may be incorrect) and completeness and confidentiality (the access records can be modified). Blockchain technology with decentralization, verifiability, and immutability properties can solve these problems. Motivated by these facts, in this article, we construct a trusted and efficient cross-domain access control system based on blockchain. Consequently, we integrate blockchain and role mapping technology to provide reliable and verifiable cross-domain access process. We use blockchain to record user roles, role mapping rules, access policies, and audit records, realizing user self-validation, and access nonreputation. Considering the low throughput of the blockchain, we design an efficient smart contract to make the access decision based on the access history of users. Finally, a performance evaluation of the system is presented to demonstrate the feasibility of the proposed system.

The internet of things (IoT) devices are expected to collect vast amounts of data that support different kinds of applications such as health monitor, smart home, and traffic management. However, its characteristics such as resource-constrained nature, dynamicity, and large-scale growth bring challenges to secure IoT data sharing. Nowadays, blockchain-based ciphertext-policy attribute-based encryption (CP-ABE) was proposed to realize secure IoT data sharing. In blockchain-based CP-ABE data sharing schemes, the data are encrypted and stored in the cloud. Once users want to process the data, they should download and then decrypt the ciphertext in the client-end, and after processing the data, users encrypt and upload the ciphertext onto the cloud. This outweighs the advantage of using cloud computing resources. Fully homomorphic encryption (FHE) and homomorphic signature technology may be adopted to realize ciphertext computation and for correctness checking of ciphertext computation results. In this paper, we propose a secure and computable IoT data sharing system to ensure users enjoying the computation convenience of the cloud-end. Specifically, the proposed system integrates CP-ABE and FHE to realize secure IoT data sharing and ciphertext computation. In addition, we generated homomorphic signatures of ciphertexts to enable users to check the correctness of the ciphertext computation results. Moreover, to supervise the cloud, providing the honest IoT data access control, storage, and computing services for users, we recorded the access policy of the data, the hash of the data, the signature of the ciphertext, and the homomorphic signature of the ciphertext on the blockchain. The performance evaluation and security analysis show the proposed scheme is practical and secure.