Abstract: Process and device for secured authentication of the transmission of data between two terminals includes a secured authentication process for the communication between a user's station and a server station, through a communication network, the user's station bring the content of an authentication device depending on information coming from a server station, in which a link is established between the user's station and the server station, a server code is chosen at random at the level of the server station, representative data of the server code are transmitted in a first server-to-user direction, thanks to those data, a corresponding user's code is recognized in the content of the authentication device, the recognized user's code is transmitted in a second user-to-server direction, the user's code is compared with the server code, and the authentication is validated if the user's code is identical to the server code.