Abstract
Crowdsensed Data Trading (CDT) is a novel data trading paradigm, in which each data consumer can publicize its data demand as some crowdsensing tasks, and some mobile users (i.e., data sellers) can compete for these tasks, collect the corresponding data, and sell the results to the consumers. Existing CDT systems generally depend on a data trading broker, which will inevitably cause data consumers' concerns on the trustworthiness of the systems and truthfulness of the data. To address this problem, we propose a Blockchain-based Crowdsensed Data Trading (BCDT) system, mainly containing a smart contract, called BCDToken. First, we replace the data trading broker with blockchain to guarantee the trustworthiness of the data trading. Meanwhile, BCDToken adopts Blockchain-based Reverse Auction (BRA) to assign sensing tasks to data sellers. The BRA mechansim holds truthfulness and individual rationality, which can ensure the data sellers to report data collection costs honestly and prevent sellers to manipulate the auction. Moreover, we implement a Secure Truth Discovery and reliability Rating (STDR) mechanism in BCDToken based on homomorphic cryptography, which can incentivize sellers to upload the truthful data and consumers to rate truthfully the reliabilities of sellers based on the collected data without revealing any privacy of data. Additionally, we also deploy BCDToken on an Ethereum test network to demonstrate its practicability and significant performances.