Perfect Secure Computation in Two Rounds

Conference paper
Part of the Lecture Notes in Computer Science book series (LNCS, volume 11239)


We show that any multi-party functionality can be evaluated using a two-round protocol with perfect correctness and perfect semi-honest security, provided that the majority of parties are honest. This settles the round complexity of information-theoretic semi-honest MPC, resolving a longstanding open question (cf. Ishai and Kushilevitz, FOCS 2000). The protocol is efficient for \({\mathrm {NC}}^1\) functionalities. Furthermore, given black-box access to a one-way function, the protocol can be made efficient for any polynomial functionality, at the cost of only guaranteeing computational security.

Technically, we extend and relax the notion of randomized encoding to specifically address multi-party functionalities. The property of a multi-party randomized encoding (MPRE) is that if the functionality g is an encoding of the functionality f, then for any (permitted) coalition of players, their respective outputs and inputs in g allow them to simulate their respective inputs and outputs in f, without learning anything else, including the other outputs of f.


Random Encryption (RE) Round Complexity Multiparty Functionality Honest Majority Adversarial Minorities 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



We are grateful to Yuval Ishai, Akshayaram Srinivasan, Muthuramakrishnan Venkitasubramaniam, and Hoteck Wee for valuable discussions and to the anonymous referees of TCC 2018 for carefully reading this paper and for providing us with helpful feedback.


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Copyright information

© International Association for Cryptologic Research 2018

Authors and Affiliations

  1. 1.Tel-Aviv UniversityTel AvivIsrael
  2. 2.Weizmann Institute of ScienceRehovotIsrael

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