Asymmetric Distributed Trust

Authors Christian Cachin , Björn Tackmann

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Author Details

Christian Cachin
  • University of Bern, Switzerland
Björn Tackmann
  • DFINITY Foundation, Zürich, Switzerland


The authors thank Orestis Alpos, Sabine Brunner, Marko Vukolić, and Luca Zanolini for interesting discussions. Work done while both authors were at IBM Research - Zurich.

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Christian Cachin and Björn Tackmann. Asymmetric Distributed Trust. In 23rd International Conference on Principles of Distributed Systems (OPODIS 2019). Leibniz International Proceedings in Informatics (LIPIcs), Volume 153, pp. 7:1-7:16, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


Quorum systems are a key abstraction in distributed fault-tolerant computing for capturing trust assumptions. They can be found at the core of many algorithms for implementing reliable broadcasts, shared memory, consensus and other problems. This paper introduces asymmetric Byzantine quorum systems that model subjective trust. Every process is free to choose which combinations of other processes it trusts and which ones it considers faulty. Asymmetric quorum systems strictly generalize standard Byzantine quorum systems, which have only one global trust assumption for all processes. This work also presents protocols that implement abstractions of shared memory and broadcast primitives with processes prone to Byzantine faults and asymmetric trust. The model and protocols pave the way for realizing more elaborate algorithms with asymmetric trust.

Subject Classification

ACM Subject Classification
  • Theory of computation → Cryptographic protocols
  • Software and its engineering → Distributed systems organizing principles
  • Quorums
  • consensus
  • distributed trust
  • blockchains
  • cryptocurrencies


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