The invention relates to a system and a method for authenticating a user. A removable storage medium (12) has at least one storage area in which identification data for identifying the removable storage medium (12) are stored, in this storage area or in a further storage area of the removable storage medium (12) data of a digital certificate (14) being stored. Further, a data processing system (18) is provided to which the removable storage medium (12) is connected via a data transfer connection. The identification data and the data of the digital certificate (14) are transferred from the removable storage medium to the data processing system (18). The data processing system (18) processes the identification data and the data of the digital certificate (14) and authenticates the user.