A method for securing the exchange of data between a client module and a server module includes steps where: the token module initializes a token and the client module sends the data, which includes a unique identifier and the initialized token to a first security module of the server module; the first security module and the second security module exchange security data bilaterally with one another; the server module transforms the received token; the client module receives the server data, verifies the token and transforms the latter; the client module sends the data, which includes the transformed token to the second security module of the server module, which receives the data, and verifies the identifier and the transformed token; and the second security module communicates with the destination module.