Résumé : The erosion of trust put in traditional database servers and in Database Service Providers, the growing interest for different forms of data dissemination and the concern for protecting children from suspicious Internet content are different factors that lead to move the access control from servers to clients. Several encryption schemes can be used to serve this purpose but all suffer from a static way of sharing data. With the emergence of hardware and software security elements on client devices, more dynamic client-based access control schemes can be devised. This paper proposes an efficient client-based evaluator of access control rules for regulating access to XML documents. This evaluator takes benefit from a dedicated index to quickly converge towards the authorized parts of a - potentially streaming - document. Additional security mechanisms guarantee that prohibited data can never be disclosed during the processing and that the input document is protected from any form of tampering. Experiments on synthetic and real datasets demonstrate the effectiveness of the approach.