Publications

Hopper: Bounded-Memory Collaborative Debiasing for Byzantine-Tolerant Peer Sampling

Published in NCA, 2026

Byzantine-tolerant peer sampling relies on continuously refreshed views, yet an adversary can bias the identifier streams used to construct them. Frequency-aware debiasing downweights overrepresented identifiers, but existing designs rely on cumulative per-identifier counts. We show that even exact, unbounded counters fail under a delayed balanced attack, in which a long benign prefix masks a subsequent adversarial frequency shift. We introduce Hopper, a bounded-memory debiasing protocol for Byzantine-tolerant peer sampling. We identify the stream-estimation properties required for debiasing and select BitMatcher as the estimator that best preserves adversarial frequency structure among the evaluated alternatives. Read more

Location: Syracuse, Italy

Recommended citation: Augusta Mukam, Joachim Bruneau-Queyreix, Laurent Reveillère. Hopper: Bounded-Memory Collaborative Debiasing for Byzantine-Tolerant Peer Sampling. IEEE International Symposium on Network Computing and Applications, Nov 2026, Syracuse, Italy. ⟨hal-05748202v2⟩. keywords: {Fault tolerance;Protocols;Sketches;Collaboration;Peer-to-peer computing;Blockchains;Object recognition;Resilience;Gossip;Peer Sampling;Distributed System;Byzantine tolerance;Eclipse Attacks},
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AUPE: Collaborative Byzantine fault-tolerant peer-sampling

Published in NCA, 2024

Peer sampling is a crucial primitive in distributed systems, used to manage overlays and disseminate information in large-scale scenarios such as permissionless blockchain systems. Its purpose is to maintain and regularly update a local and partial snapshot, or view, of the complete system’s membership. These protocols are often targeted by malicious actors who aim to disrupt higher-level protocols. Typically, an adversary who controls a set of Byzantine nodes attempts to manipulate how legitimate nodes perceive the presence of Byzantine ones by increasing their representation in the view of honest nodes. Read more

Received Best Paper award during the conference

Held in Bertinoro, Italy

Recommended citation: A. Mukam, J. Bruneau-Queyreix and L. Réveillère, "AUPE: Collaborative Byzantine fault-tolerant peer-sampling," 2024 22nd International Symposium on Network Computing and Applications (NCA), Bertinoro, Italy, 2024, pp. 17-24, doi: 10.1109/NCA61908.2024.00015. keywords: {Fault tolerance;Protocols;Limiting;Fault tolerant systems;Collaboration;Peer-to-peer computing;Blockchains;Object recognition;Resilience;Gossip;Peer Sampling;Distributed System;Byzantine tolerance;Eclipse Attacks},
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Utilisation de noeuds de confiance pour les protocoles d’échantillonage de pairs tolérants aux attaques byzantines

Published in Compas, 2023

Les blockchains sont des systèmes distribués avec des contraintes propres à satisfaire. Il faut par exemple s’assurer que les nœuds du système aient un état à jour dans des délais opportun, mais aussi que l’intégrité voir de la confidentialité des données soit préservée. Read more

Poster presentation, held in Annecy, France

Recommended citation: Augusta Mukam, Joachim Bruneau-Queyreix, Laurent Réveillère. Utilisation de noeuds de confiance pour les protocoles d’échantillonnage de pairs tolérants aux attaques byzantines, juillet 2023, Annecy, France.
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Byzantine-Resilient Peer Sampling for Large-Scale Distributed Systems

Published in University of Bordeaux, 2026

Peer sampling services are foundational primitives in large-scale distributed systems, providing each node with a continuously refreshed, near-uniform view of the system membership. Gossip-based implementations are particularly well-suited to this task owing to their scalability, self-healing properties, and robustness to churn. However, in open, adversarial environments such as public blockchain networks, Byzantine nodes can systematically bias view exchanges, corrupting the sampling distribution and enabling attacks such as eclipse attacks, denial-of-service attacks, and manipulation of consensus protocols. This thesis addresses the problem of Byzantine-resilient gossip-based peer sampling and focuses on proposing scalable, memory-efficient solutions. Read more

Recommended citation: Augusta Mukam. (2026). "Byzantine-Resilient Peer Sampling for Large-Scale Distributed Systems." PhD Thesis, University of Bordeaux.
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