Perfectly-secure key distribution for dynamic conferences

Carlo Blundo, Alfredo De Santis, Amir Herzberg, Shay Kutten, Ugo Vaccaro, Moti Yung

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

858 Scopus citations


A key distribution scheme for dynamic conferences is a method by which initially an (off-line) trusted server distributes private individual pieces of information to a set of users. Later any group of users of a given size (a dynamic conference) is able to compute a common secure key. In this paper we study the theory and applications of such perfectly secure systems. In this setting, any group of t users can compute a common key by each user computing using only his private piece of information and the identities of the other t — 1 group users. Keys are secure against coalitions of up to k users, that is, even if k users pool together their pieces they cannot compute anything about a key of any t-size conference comprised of other users. First we consider a non-interactive model where users compute the common key without any interaction. We prove a lower bound on the size of the user’s piece of information of (formula presented) times the size of the common key. We then establish the optimality of this bound, by describing and analyzing a scheme which exactly meets this limitation (the construction extends the one in [2]). Then, we consider the model where interaction is allowed in the common key computation phase, and show a gap between the models by exhibiting an interactive scheme in which the user’s information is only k +1 — 1 times the size of the common key. We further show various applications and useful modifications of our basic scheme. Finally, we present its adaptation to network topologies with neighborhood constraints.

Original languageEnglish
Title of host publicationAdvances in Cryptology — CRYPTO 1992 - 12th Annual International Cryptology Conference, Proceedings
EditorsErnest F. Brickell
PublisherSpringer Verlag
Number of pages16
ISBN (Print)9783540573401
StatePublished - 1993
Externally publishedYes
Event12th Annual International Cryptology Conference, CRYPTO 1992 - Santa Barbara, United States
Duration: 16 Aug 199220 Aug 1992

Publication series

NameLecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics)
Volume740 LNCS
ISSN (Print)0302-9743
ISSN (Electronic)1611-3349


Conference12th Annual International Cryptology Conference, CRYPTO 1992
Country/TerritoryUnited States
CitySanta Barbara

Bibliographical note

Publisher Copyright:
© Springer-Verlag Berlin Heidelberg 1993.


* Partially supported by Italian Ministry of University and Research (M.U.R.S.T.) and by National Council for Research (C.N.R.) under grant 91.02326.CT12. E.F. Bnckell (Ed.): Advances in Cryptology - CRYPT0 '92, LNCS 740, pp. 471-486, 1993. 0 Spnnger-Verlag Berlin Heidelberg 1993

FundersFunder number
Ministry of University and Research
National Council for Research


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