Abstract: An authentication method using a first authentication factor and a second biometric authentication factor, the authentication device having a server(s) and an authentication terminal, including a device for acquiring user biometric information, the user terminal storing a reference biometric template of the user and an identifier of the user, the method involving the following asynchronous steps: transmitting the identifier of the user to the server(s) when a first communication condition dependent on a position of the user terminal is met, receiving by the user terminal a challenge originating from the sever(s), signing the challenge to produce a signed challenge, encrypting the reference biometric template, transmitting the signed challenge, the cipher of the reference biometric template and the identifier of the user to the at least one authentication terminal.

Abstract: The invention relates to an electronic transaction method. The method comprises carrying out an initiation communication between a terminal device and a mobile device, and carrying out an electronic transaction on the basis of the initiation communication between the terminal device and the mobile device. The initiation communication between the terminal device and the mobile device is a unidirectional communication in which initiation data is transmitted from the terminal device to the mobile device. The invention furthermore relates to a terminal device for use in an electronic transaction method, and to a transaction application for a mobile device for use in an electronic transaction method.