A method and apparatus are provided for processing data. The method includes a step of receiving, during a first communication session established with said server, a request formulated by a first user defining at least one processing operation to be executed on first data, and a step of executing said processing operation on said first data, during a second communication session established with said server after said first session for a second user. The step of executing is applied on condition that the second user has been authenticated via a strong authentication method during the second session and that a relationship between the first and second users has been verified.