An Accountable Decryption System Based on Privacy-Preserving Smart Contracts

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


Colleges, School and Institutes

External organisations

  • Southern University of Science and Technology
  • Swinburne University of Technology, Melbourne, Australia
  • Fetch.AI, St John's Innovation Center, Cambridge


Accountability is a fundamental after-the-fact approach to detect and punish illegal actions during the execution of a warrant for accessing users' sensitive data. To achieve accountability in a security protocol, a trusted authority is required, denoted as judge, to faithfully cooperate with the rest of the entities in the system. However, malicious judges or uncooperative protocol participants may void the accountability mechanism in practice, for example by fabricating fake evidence or by refusing to provide any evidence at all. To provide remediation to these issues, in this paper we propose Fialka, a novel accountable decryption system based on privacy-preserving smart contracts (PPSC). The neutrality that is inherent to a secure blockchain platform is inherited by PPSC which are then used in our approach as an accountable key manager as well as a transparent judge. To the best of our knowledge, we present the first PPSC-based accountable decryption system to increase the transparency of warrant execution with formal definitions and proofs. Furthermore, we provide and evaluate a prototype implementation using the PPSC-enabled platform Oasis Devnet, which additionally demonstrates the feasibility of Fialka.


Original languageEnglish
Title of host publication23rd Information Security Conference, (ISC 2020)
Publication statusAccepted/In press - 31 Aug 2020
Event23rd Information Security Conference (ISC 2020) - Surabaya, Indonesia
Duration: 16 Dec 202020 Dec 2020

Publication series

NameLecture Notes in Computer Science
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference23rd Information Security Conference (ISC 2020)


  • Accountability, Privacy-Preserving Smart Contract, Blockchain