Combining the supply chain with blockchain provides an immutable and publicly transparent ledger for the supply chain data history, addressing the issue of information asymmetry. Nevertheless, challenges still exist, including privacy leakage in data access and inefficiency in traceability, which hinders the application of blockchain in supply chains. To address these issues, we propose an adaptive access and tracking method for supply chain data based on sharding blockchain. Dividing the participating nodes into different shards enables independent and parallel verification and confirmation of transaction data, which enhances the efficiency and scalability of transaction processing in the supply chain ecosystem. In terms of the privacy level, the on-demand processing method for transaction data is leveraged, and the predicate encryption access control scheme with ciphertext commitment is constructed for the private data, which provides secure and adaptive access to sharding transaction data. Furthermore, a data tracking method is constructed with the trace source contract and Merkle tracking tree, which links upstream and downstream data in the supply chain, enabling the location of relevant tracking data and reducing the time required for data queries, achieving accurate supply chain traceability. The security analysis and experimental results demonstrate that the method is of flexibility and practicality.

The low throughput of traditional blockchain can hardly support the demand of high-frequency and high-concurrent application scenarios, which severely restricts the practical application of blockchain and becomes a bottleneck for blockchain development. Sharding is a potential solution to this issue. Existing sharding schemes mostly use complicated PBFT or its variants consensus protocols, with diminishing consensus performance as the number of nodes grows, and global consistency of transaction data is a challenge due to parallel block generation. Aiming at the above problems, we propose an efficient and scalable sharding blockchain system named FortunChain that comprises a verification chain and multiple sharding chains. In the FortunChain, a novel Tyche consensus protocol is designed to select the set of sharding verification nodes and accounting nodes probabilistically leveraging the newly constructed elliptic curve-based verifiable random function (EC-VRF), which ensures the efficiency, unpredictability and security of node selection. Multi-period, fast and dynamic sharding accounting is implemented in the sharding chain to improve the performance of transaction processing. After that, the verification chain is responsible for the secondary verification by applying the batch verification algorithm to the blocks submitted by the shards and then generating the verification block. Each shard stores the sharding state by synchronizing the verification chain to realize the state sharding and ensure the global consistency of the transaction data. Simulation results show that the throughput of FortunChain can reach approximately 6540tx/s and the estimated latency is 8.59s, which demonstrates its efficiency and feasibility.

Cloud computing has brought great convenience to data storage and resource sharing, however, there are still concerns about data security and service quality. Attribute-based encryption (ABE) and searchable encryption (SE) are always adopted to achieve data access authorization and data retrieval on encrypted data in data sharing, respectively. But more efficient and accurate methods have been always pursued. Moreover, the spoofing attack is another important aspect that raises concerns, especially when it comes to reliability of search results and online payments. Blockchain, an emerging technology that can be used to solve the problem of trust, has shown great application potential in finance and data sharing. Based on blockchain, we propose an attribute-based conjunctive keyword search (ABCKS) scheme with verifiability and fairness. In this paper, data privacy-preserving, fine-grained access control, and multi-keywords search can be supported simultaneously. Blockchain and smart contract are employed to facilitate the search result verification process and ensure fair payment in the trustless case. Furthermore, we reduce the user's decryption load to a constant level by performing partial decryption on the cloud side. Finally, the results of the performance evaluation indicate that our scheme has higher efficiency and security.