Paper 2022/1498

Simple, Fast, Efficient, and Tightly-Secure Non-Malleable Non-Interactive Timed Commitments

Peter Chvojka
Tibor Jager, University of Wuppertal

Timed commitment schemes, introduced by Boneh and Naor (CRYPTO 2000), can be used to achieve fairness in secure computation protocols in a simple and elegant way. The only known non-malleable construction in the standard model is due to Katz, Loss, and Xu (TCC 2020). This construction requires general-purpose zero knowledge proofs with specific properties, and it suffers from an inefficient commitment protocol, which requires the committing party to solve a computationally expensive puzzle. We propose new constructions of non-malleable non-interactive timed commitments, which combine (an extension of) the Naor-Yung paradigm used to construct IND-CCA secure encryption with a non-interactive ZK proofs for a simple algebraic language. This yields much simpler and more efficient non-malleable timed commitments in the standard model. Furthermore, our constructions also compare favourably to known constructions of timed commitments in the random oracle model, as they achieve several further interesting properties that make the schemes very practical. This includes the possibility of using a homomorphism for the forced opening of multiple commitments in the sense of Malavolta and Thyagarajan (CRYPTO 2019), and they are the first constructions to achieve public verifiability, which seems particularly useful to apply the homomorphism in practical applications.

Available format(s)
Public-key cryptography
Publication info
timed release cryptography timed commitments time-lock puzzles tightness
Contact author(s)
chvojka p @ gmail com
jager @ uni-wuppertal de
2022-12-14: last of 2 revisions
2022-10-31: received
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      author = {Peter Chvojka and Tibor Jager},
      title = {Simple, Fast, Efficient, and Tightly-Secure Non-Malleable Non-Interactive Timed Commitments},
      howpublished = {Cryptology ePrint Archive, Paper 2022/1498},
      year = {2022},
      note = {\url{}},
      url = {}
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