Incoercible multi-party computation and universally composable receipt-free voting

Jöel Alwen*, Rafail Ostrovsky, Hong Sheng Zhou, Vassilis Zikas

*Corresponding author for this work

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

Abstract / Description of output

Composable notions of incoercibility aim to forbid a coercer from using anything beyond the coerced parties’ inputs and outputs to catch them when they try to deceive him. Existing definitions are restricted to weak coercion types, and/or are not universally composable. Furthermore, they often make too strong assumptions on the knowledge of coerced parties—e.g., they assume they known the identities and/or the strategies of other coerced parties, or those of corrupted parties— which makes them unsuitable for applications of incoercibility such as e-voting, where colluding adversarial parties may attempt to coerce honest voters, e.g., by offering them money for a promised vote, and use their own view to check that the voter keeps his end of the bargain. In this work we put forward the first universally composable notion of incoercible multi-party computation, which satisfies the above intuition and does not assume collusions among coerced parties or knowledge of the corrupted set. We define natural notions of UC incoercibility corresponding to standard coercion-types, i.e., receipt-freeness and resistance to full-active coercion. Importantly, our suggested notion has the unique property that it builds on top of the well studied UC framework by Canetti instead of modifying it. This guarantees backwards compatibility, and allows us to inherit results from the rich UC literature. We then present MPC protocols which realize our notions of UC incoercibility given access to an arguably minimal setup—namely honestly generate tamper-proof hardware performing a very simple cryptographic operation—e.g., a smart card. This is, to our knowledge, the first proposed construction of an MPC protocol (for more than two parties) that is incoercibly secure and universally composable, and therefore the first construction of a universally composable receipt-free e-voting protocol.

Original languageEnglish
Title of host publicationAdvances in Cryptology - CRYPTO 2015
Subtitle of host publication35th Annual Cryptology Conference, Proceedings
EditorsMatthew Robshaw, Rosario Gennaro
Place of PublicationBerlin, Heidelberg
Number of pages18
ISBN (Electronic)978-3-662-48000-7
ISBN (Print)978-3-662-47999-5
Publication statusPublished - 20 Aug 2015
Event35th Annual Cryptology Conference - Santa Barbara, United States
Duration: 16 Aug 201520 Aug 2015

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
PublisherSpringer, Berlin, Heidelberg
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference35th Annual Cryptology Conference
Abbreviated titleCRYPTO 2015
Country/TerritoryUnited States
CitySanta Barbara
Internet address

Keywords / Materials (for Non-textual outputs)

  • Multi-party computation
  • Receipt-freeness
  • Universal composition


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