An Offline Delegatable Cryptocurrency System

Research output: Chapter in Book/Report/Conference proceedingConference contribution


  • Rujia Li
  • Qin Wang
  • Qi Wang
  • Xinrui Zhang
  • Yang Xiang

Colleges, School and Institutes

External organisations

  • Swinburne University of Technology, Melbourne, Australia
  • Nankai University
  • Southern University of Science and Technology


Abstract—Blockchain-based cryptocurrencies, facilitating the convenience of payment by providing a decentralized online solution, have not been widely adopted so far due to slow confirmation of transactions. Offline delegation offers an efficient way to exchange coins. However, in such an approach, the coins that have been delegated confront the risk of being spent twice since the delegator’s behaviour cannot be restricted easily on account of the absence of effective supervision. Even if a third party can be regarded as a judge between the delegator and delegatee for secure transactions, she still faces the threat of being compromised or providing misleading assure. Moreover, the approach equipped with a third party contradicts the real intention of decentralized cryptocurrency systems. In this paper, we propose DelegaCoin, an offline delegatable cryptocurrency system to mitigate such an issue. We exploit trusted execution environments (TEEs) as decentralized “virtual agents” to prevent malicious delegation. In our scheme, an owner can delegate his coins through offline-transactions without interacting with the blockchain network. We provide a formal model with provable security analysis for our proposed system. We further implement a prototype and provide a preliminary evaluation. The analysis and results demonstrate that our scheme is provably secure and practically feasible.


Original languageEnglish
Title of host publication2021 IEEE International Conference on Blockchain and Cryptocurrency
Subtitle of host publicationICBC 2021
Publication statusAccepted/In press - 17 Feb 2021