Broadcast CONGEST Algorithms Against Eavesdroppers

Yael Hitron, Merav Parter, Eylon Yogev

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


An eavesdropper is a passive adversary that aims at extracting private information on the input and output values of the network's participants, by listening to the traffic exchanged over a subset of edges in the graph. We consider secure congest algorithms for the basic broadcast task, in the presence of eavesdropper (edge) adversaries. For D-diameter n-vertex graphs with edge connectivity Θ(f), we present f-secure broadcast algorithms that run in Õ(D + √fn) rounds. These algorithms transmit some broadcast message m to all the vertices in the graph, in a way that is information-theoretically secure against an eavesdropper controlling any subset of at most f edges in the graph. While our algorithms are heavily based on network coding (secret sharing), we also show that this is essential. For the basic problem of secure unicast we demonstrate a network coding gap of Ω(n) rounds. In the presence of vertex adversaries, known as semi-honest, we introduce the Forbidden-Set Broadcast problem: In this problem, the vertices of the graph are partitioned into two sets, trusted and untrusted, denoted as R, F ⊆ V, respectively, such that G[R] is connected. It is then desired to exchange a secret message m between all the trusted vertices while leaking no information to the untrusted set F. Our algorithm works in Õ(D + √|R|) rounds and its security guarantees hold even when all the untrusted vertices F are controlled by a (centralized) adversary.

Original languageEnglish
Title of host publication36th International Symposium on Distributed Computing, DISC 2022
EditorsChristian Scheideler
PublisherSchloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing
ISBN (Electronic)9783959772556
StatePublished - 1 Oct 2022
Externally publishedYes
Event36th International Symposium on Distributed Computing, DISC 2022 - Augusta, United States
Duration: 25 Oct 202227 Oct 2022

Publication series

NameLeibniz International Proceedings in Informatics, LIPIcs
ISSN (Print)1868-8969


Conference36th International Symposium on Distributed Computing, DISC 2022
Country/TerritoryUnited States


  • congest
  • edge-connectivity
  • secret sharing


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