Secure computation without authentication

Boaz Barak*, Ran Canetti, Yehuda Lindell, Rafael Pass, Tal Rabin

*Corresponding author for this work

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

57 Scopus citations


In the setting of secure multiparty computation, a set of parties wish to jointly compute some function of their inputs. Such a computation must preserve certain security properties, like privacy and correctness, even if some of the participating parties or an external adversary collude to attack the honest parties. Until this paper, all protocols for general secure computation assumed that the parties can communicate reliably via authenticated channels. In this paper, we consider the feasibility of secure computation without any setup assumption. We consider a completely unauthenticated setting, where all messages sent by the parties may be tampered with and modified by the adversary (without the honest parties being able to detect this fact). In this model, it is not possible to achieve the same level of security as in the authenticated-channel setting. Nevertheless, we show that meaningful security guarantees can be provided. In particular, we define a relaxed notion of what it means to "securely compute" a function in the unauthenticated setting. Then, we construct protocols for securely realizing any functionality in the stand-alone model, with no setup assumptions whatsoever. In addition, we construct universally composable protocols for securely realizing any functionality in the common reference string model (while still in an unauthenticated network). We also show that our protocols can be used to provide conceptually simple and unified solutions to a number of problems that were studied separately in the past, including password-based authenticated key exchange and non-malleable commitments.

Original languageEnglish
Title of host publicationAdvances in Cryptology - CRYPTO 2005 - 25th Annual International Cryptology Conference, Proceedings
Number of pages17
StatePublished - 2006
Externally publishedYes
Event25th Annual International Cryptology Conference, CRYPTO 2005 - Santa Barbara, CA, United States
Duration: 14 Aug 200518 Aug 2005

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume3621 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference25th Annual International Cryptology Conference, CRYPTO 2005
Country/TerritoryUnited States
CitySanta Barbara, CA


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