Abstract: A memory card or smart card for emitting sound signals. The card incorporates at least one controlling electronic micromodule which includes in particular processor circuits and a memory in which binary data is stored. An excitation device is connected to the micromodule to convert the binary data into sound signals. A vibrating membrane is connected to the excitation device to emit the sound signals. The vibrating mechanism is constituted by the card itself. Such a design is applicable in particular to transmitting binary data over a telephone line by acoustic coupling with a telephone.

Abstract: When access is requested, the method consists in causing the portable device to transmit at least an identity sequence containing at least the value of a cryptogram (Ci) which is the result of an iterative algorithm (A2) being executed that is based on a non-invertible secret-key function (F2), and in causing the server to compute successive cryptograms (Q1, Q2, . . . ) on the basis of a cryptogram (Q0) and by using the same algorithm (A2) until a cryptogram (Qn) is found whose value is equal to the value of the cryptogram (Ci) so as to validate access. The method is suitable in particular for use in a home banking application.