Publications de Rachid Guerraoui

ARGO: Overcoming hardware dependence in distributed learning

Mobile devices offer a valuable resource for distributed learning alongside traditional computers, encouraging energy efficiency and privacy through local computations. However, the hardware limitations of these devices makes it impossible to use classical ...

2025

Partial Synchrony for Free: New Upper Bounds for Byzantine Agreement

Rachid Guerraoui, Jovan Komatovic, Pierre Philippe Civit, Manuel José Ribeiro Vidigueira

Byzantine agreement allows n processes to decide on a common value, in spite of arbitrary failures. The seminal Dolev-Reischuk bound states that any deterministic solution to Byzantine agreement exchanges Ω(n2) bits. In synchronous networks, with a known u ...

Society for Industrial and Applied Mathematics2025

The Utility and Complexity of In- and Out-of-Distribution Machine Unlearning

Rachid Guerraoui, Youssef Allouah

Machine unlearning, the process of selectively removing data from trained models, is increasingly crucial for addressing privacy concerns and knowledge gaps post-deployment. Despite this importance, existing approaches are often heuristic and lack formal g ...

ICLR2025

Repeated Agreement is Cheap! On Weak Accountability and Multishot Byzantine Agreement

Rachid Guerraoui, Jovan Komatovic, Pierre Philippe Civit, Manuel José Ribeiro Vidigueira

Byzantine Agreement (BA) allows 𝑛 processes to propose input values to reach consensus on a common, valid 𝐿 𝑜-bit value, even in the presence of up to 𝑡 < 𝑛 faulty processes that can deviate arbitrarily from the protocol. Although strategies like randomiza ...

ACM2025

Efficient Federated Search for Retrieval-Augmented Generation

Rachid Guerraoui, Anne-Marie Kermarrec, Rafael Pereira Pires, Diana Andreea Petrescu, Marinus Abraham de Vos

Large language models (LLMs) have demonstrated remarkable capabilities across various domains but remain susceptible to hallucinations and inconsistencies, limiting their reliability. Retrieval-augmented generation (RAG) mitigates these issues by grounding ...

ACM2025

Evaluating Blockchain Fault Tolerance with Stabl

Rachid Guerraoui, Gauthier Jérôme Timothée Voron

Despite their distributed nature, blockchains frequently experience failures that disrupt availability, delay transactions, and, in some cases, cause total network outages. Ensuring fault tolerance is critical for the reliability of blockchain-based applic ...

IEEE2025

Efficient Signature-Free Validated Agreement

Rachid Guerraoui, Jovan Komatovic, Pierre Philippe Civit, Manuel José Ribeiro Vidigueira

Byzantine agreement enables n processes to agree on a common L-bit value, despite up to t > 0 arbitrary failures. A long line of work has been dedicated to improving the bit complexity of Byzantine agreement in synchrony. This has culminated in COOL, an er ...

Schloss Dagstuhl- Leibniz-Zentrum fur Informatik GmbH, Dagstuhl Publishing2024

Robust Sparse Voting

Rachid Guerraoui, Youssef Allouah, Oscar Jean Olivier Villemaud, Le Nguyen Hoang

Many applications, such as content moderation and recommendation, require reviewing and scoring a large number of alternatives. Doing so robustly is however very challenging. Indeed, voters' inputs are inevitably sparse: most alternatives are only scored b ...

2024

Rapidly verifiable aggregate signatures

Rachid Guerraoui, Gauthier Jérôme Timothée Voron, Martina Camaioni, Matteo Monti, Manuel José Ribeiro Vidigueira, Pierre-Louis Blaise Roman

A method for aggregating digital signatures comprises the following steps carried out by a signature aggregator: receiving first data packages from signers, each first data package comprising a signer identifier, a payload, and a payload signature; verifyi ...

2024

Robust Machine Learning - Distributed Methods for Safe AI

Rachid Guerraoui, Nirupam Gupta, Rafaël Benjamin Pinot

Today, machine learning algorithms are often distributed across multiple machines to leverage more computing power and more data. However, the use of a distributed framework entails a variety of security threats. In particular, some of the machines may mis ...

Springer2024