Abstract: The invention relates to a method and devices allowing exchange of data between authorized bearers of crediting means (1) to be identified, approved and possibly coded and to remote centralized processing machines (3) via specific terminal units (2). The data produced by a bearer of a crediting means (1) after connection of said means (1) to a terminal unit (2) and sending of the identity of said means (1) are approved by a logic generation unit (15) of the means (1) from an individualization code and from transaction data. The invention applies to the exchange of data in an insecure environment and more particularly to bank credit card systems.