Abstract
The security notion of covert security introduced by Aumann and Lindell (TCC’07) allows the adversary to successfully cheat and break security with a fixed probability 1 - ϵ, while with probability ϵ, honest parties detect the cheating attempt. Asharov and Orlandi (ASIACRYPT’12) extend covert security to enable parties to create publicly verifiable evidence about misbehavior that can be transferred to any third party. This notion is called publicly verifiable covert security (PVC) and has been investigated by multiple works. While these two notions work well in settings with known identities in which parties care about their reputation, they fall short in Internet-like settings where there are only digital identities that can provide some form of anonymity. In this work, we propose the notion of financially backed covert security (FBC), which ensures that the adversary is financially punished if cheating is detected. Next, we present three transformations that turn PVC protocols into FBC protocols. Our protocols provide highly efficient judging, thereby enabling practical judge implementations via smart contracts deployed on a blockchain. In particular, the judge only needs to non-interactively validate a single protocol message while previous PVC protocols required the judge to emulate the whole protocol. Furthermore, by allowing an interactive punishment procedure, we can reduce the amount of validation to a single program instruction, e.g., a gate in a circuit. An interactive punishment, additionally, enables us to create financially backed covert secure protocols without any form of common public transcript, a property that has not been achieved by prior PVC protocols.
Original language | English |
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Title of host publication | Public-Key Cryptography - PKC 2022 - 25th IACR International Conference on Practice and Theory of Public-Key Cryptography, Proceedings |
Editors | Goichiro Hanaoka, Junji Shikata, Yohei Watanabe |
Publisher | Springer Science and Business Media Deutschland GmbH |
Pages | 99-129 |
Number of pages | 31 |
ISBN (Print) | 9783030971304 |
DOIs | |
State | Published - 2022 |
Event | 25th IACR International Conference on Practice and Theory of Public-Key Cryptography, PKC 2022 - Virtual, Online Duration: 8 Mar 2022 → 11 Mar 2022 |
Publication series
Name | Lecture Notes in Computer Science |
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Volume | 13178 LNCS |
ISSN (Print) | 0302-9743 |
ISSN (Electronic) | 1611-3349 |
Conference
Conference | 25th IACR International Conference on Practice and Theory of Public-Key Cryptography, PKC 2022 |
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City | Virtual, Online |
Period | 8/03/22 → 11/03/22 |
Bibliographical note
Publisher Copyright:© 2022, International Association for Cryptologic Research.
Funding
Acknowledgments. The first, third, and fourth authors were supported by the German Federal Ministry of Education and Research (BMBF) iBlockchain project (grant nr. 16KIS0902), by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) SFB 1119 - 236615297 (CROSSING Project S7), by the BMBF and the Hessian Ministry of Higher Education, Research, Science and the Arts within their joint support of the National Research Center for Applied Cybersecurity ATHENE, and by Robert Bosch GmbH, by the Economy of Things Project. The second author was supported by the BIU Center for Research in Applied Cryptography and Cyber Security in conjunction with the Israel National Cyber Bureau in the Prime Minister’s Office, and by ISF grant No. 1316/18.
Funders | Funder number |
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Hessian Ministry of Higher Education, Research, Science and the Arts | |
National Research Center for Applied Cybersecurity ATHENE | |
Robert Bosch | |
Deutsche Forschungsgemeinschaft | SFB 1119 - 236615297 |
Bundesministerium für Bildung und Forschung | 16KIS0902 |
Israel Science Foundation | 1316/18 |
Keywords
- Covert Security
- Financial Punishment
- Multi-Party Computation (MPC)
- Public Verifiability