Journal of Blockchain Research

Volume 1 (2022)

Number 1

Scalable and secure crowdsourcing atop blockchain via off-chain payment

Pages: 19 – 27



Anxin Zhou (Shenzhen Research Institute, City University of Hong Kong)

Cong Wang (Shenzhen Research Institute, City University of Hong Kong)

Xiaohua Jia (City University of Hong Kong)


Blockchain facilitates atomic exchange by serving as a decentralized coordinator. It recently has been applied to crowdsourcing for settling the payment between the mutually untrusted data collector and data providers. However, this is still not practical due to the blockchain’s poor performance. This paper presents a crowdsourcing system that uses the blockchain in a secure and scalable fashion. A crowdsourcing task can involve an unlimited number of data providers but with a constant transaction cost. For this purpose, we design an off-chain payment system based on trusted hardware. In this way, the data collector can use offchain payment for crowdsourcing, and the blockchain mainly performs lightweight verification to ensure honest payment. We implement and evaluate an application of text data collection. The evaluation shows the desirable performance.


blockchain, off-chain payment, crowdsourcing, trusted hardware

This work was supported by the RGC of Hong Kong under Grant CityU 11213920, 11217819, 11217620, 11218521, N_CityU139/21, RFS2122-1S04, and R6021-20F, by the 26 A. Zhou, C. Wang, and X. Jia NSFC under Grant 61572412, and by Shenzhen Municipality Science and Technology Innovation Commission (grant no. SGDX20201103093004019, CityU).

Received 13 October 2021

Accepted 18 May 2022

Published 13 October 2022