This article presents a signature-free distributed algorithm which builds an atomic read/write shared memory on top of an n-process asynchronous message-passing system in which up to t < n/3 processes may commit Byzantine failures. From a conceptual point of view, this algorithm is designed to be as close as possible to the algorithm proposed by Attiya, Bar-Noy and Dolev (JACM 1995), which builds an atomic register in an n-process asynchronous message-passing system where up to t < n/2 processes may crash. The proposed algorithm is particularly simple. It does not use cryptography to cope with Byzantine processes, and is optimal from a t-resilience point of view (t < n/3). A read operation requires O(n) messages, and a write operation requires O(n 2) messages. Mémoire partagée fiable dans les systèmes asynchones avec processus Byzantins Résumé : Cet article présente une construction de mémoire partagée au dessus d'un système asynchone à passage de messages dans lequel jusqu'à t < n/3 processus peuvent avoir des comportements arbitraires (fautes Byzantines), n étant le nombre total de processsus.