Many proofs of interactive cryptographic protocols (e.g., as in Universal Composability) operate by proving the protocol at hand to be observationally equivalent to an idealized specification. While pervasive, formal tool support for observational equivalence of cryptographic protocols is still a nascent area of research. Current mechanization efforts tend to either focus on diff-equivalence, which establishes observational equivalence between protocols with identical control structures, or require an explicit witness for the observational equivalence in the form of a bisimulation relation. Our goal is to simplify proofs for cryptographic protocols by introducing a core calculus, IPDL, for cryptographic observational equivalences. Via IPDL, we aim to address a number of theoretical issues for cryptographic proofs in a simple manner, including probabilistic behaviors, distributed message-passing, and resource-bounded adversaries and simulators. We demonstrate IPDL on a number of case studies, including a distributed coin toss protocol, Oblivious Transfer, and the GMW multi-party computation protocol. All proofs of case studies are mechanized via an embedding of IPDL into the Coq proof assistant.
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This content will become publicly available on October 1, 2025
Toward A Practical Multi-party Private Set Union
This paper studies a multi-party private set union (mPSU), a fundamental cryptographic problem that allows multiple parties to compute the union of their respective datasets without revealing any additional information. We propose an efficient mPSU protocol which is secure in the presence of any number of colluding semi-honest participants. Our protocol avoids computationally expensive homomorphic operations or generic multi-party computation, thus providing an efficient solution for mPSU. The crux of our protocol lies in the utilization of new cryptographic tool, namely, Membership Oblivious Transfer (mOT). We believe that the mOT may be of independent interest. We implement our mPSU protocol and evaluate its performance. Our protocol shows an improvement of up to $80.84 times$ in terms of running time and $405.73 times$ bandwidth cost compared to the existing state-of-the-art protocols.
more » « less- Award ID(s):
- 2115075
- NSF-PAR ID:
- 10523721
- Publisher / Repository:
- Proceedings on Privacy Enhancing Technologies
- Date Published:
- Journal Name:
- Proceedings on Privacy Enhancing Technologies
- Volume:
- 2024
- Issue:
- 4
- ISSN:
- 2299-0984
- Page Range / eLocation ID:
- 622 to 635
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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