Time-lock puzzles are a mechanism for sending messages “to the future”, by allowing a sender to quickly generate a puzzle with an underlying message that remains hidden until a receiver spends a moderately large amount of time solving it. We introduce and construct a variant of a time-lock puzzle which is non-malleable, which roughly guarantees that it is impossible to “maul” a puzzle into one for a related message without solving it. Using non-malleable time-lock puzzles, we achieve the following applications: The first fair non-interactive multi-party protocols for coin flipping and auctions in the plain model without setup.Practically efficient fair multi-party protocols for coin flipping and auctions proven secure in the (auxiliary-input) random oracle model. As a key step towards proving the security of our protocols, we introduce the notion of functional non-malleability, which protects against tampering attacks that affect a specific function of the related messages. To support an unbounded number of participants in our protocols, our time-lock puzzles satisfy functional non-malleability in the fully concurrent setting. We additionally show that standard (non-functional) non-malleability is impossible to achieve in the concurrent setting (even in the random oracle model).
|Original language||American English|
|Title of host publication||Theory of Cryptography - 19th International Conference, TCC 2021, Proceedings|
|Editors||Kobbi Nissim, Brent Waters, Brent Waters|
|Publisher||Springer Science and Business Media Deutschland GmbH|
|Number of pages||33|
|State||Published - 2021|
|Event||19th International Conference on Theory of Cryptography, TCC 2021 - Raleigh, United States|
Duration: 8 Nov 2021 → 11 Nov 2021
|Name||Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)|
|Conference||19th International Conference on Theory of Cryptography, TCC 2021|
|Period||8/11/21 → 11/11/21|
Bibliographical noteFunding Information:
Acknowledgements. This work was supported in part by NSF Award SATC-1704788, NSF Award RI-1703846, NSF Award DGE-1650441, AFOSR Award FA9550-18-1-0267, DARPA Award HR00110C0086, and a JP Morgan Faculty Award. Ilan Komargodski is supported in part by an Alon Young Faculty Fellowship and by an ISF grant (No. 1774/20). This research is based upon work supported in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), via 2019-19-020700006. The views and conclusions contained herein are those of the authors and should not be interpreted as necessarily representing the official policies, either expressed or implied, of ODNI, IARPA, or the U.S. Government. The U.S. Government is authorized to reproduce and distribute reprints for governmental purposes notwithstanding any copyright annotation therein.
© 2021, International Association for Cryptologic Research.