Enabling Secure and Traceable Query Services for Internet of Things Using Blockchain

The potential value of data for comprehensive analysis and decision-making drives data trading. Because data can be considered private assets, data query processing must be done securely and privately. However, none of the previous work provides a supervision mechanism for secure execution, such as traceability. In practice, traceable query processing is imperative, since we can re-execute queries from some steps, instead of restarting from the beginning. In this paper, we propose a blockchain-based framework to enable secure and traceable skyline queries. For traceable query processing, we use blockchain to make a consensus on each query step and record the intermediate results of each step into ledgers. For secure query processing, we propose a secure dominance computation scheme so that data distribution will not be exposed although skyline queries involve arithmetical computation. The scheme utilizes scalar-product-preserving encryption for inequality identification in dominance tests. The inequality identification operator is conducted by two non-colluding blockchain networks collaboratively so that intermediate results do not leak knowledge about both data and query. Based on the dominance computation scheme, we present two secure skyline query protocols. Security analysis and extensive experiments show that our proposed protocols achieve promising results.