Interface method and device for the on-line exchange of content data in a secure manner

The invention relates to a method for the on-line exchange of contents data, comprising the following method steps: reception of a code entered by a user on an interface device ( 4 a-c), transmission of a first read request from said interface device to a first server device ( 3 ), in which are stored the respective personal cryptographic data for a number of users encoded by using a respective authentic code for said user, reception of the encoded personal cryptographic data for said user in said interface device, decoding said personal cryptographic data by means of said entered code when the entered code corresponds to the authentic code for the user, use of said personal cryptographic data to secure an exchange of contents data between said interface device and at least one second server device ( 2 a-b) and erasure of said entered code and said personal cryptographic data from said interface device.