Abstract: A method of authenticating a user for access to a software-based system via an access medium is described for simpler and faster authentication of a user. The user transmits his/her public key to the software-based system; the software-based system verifies whether the user has already been registered based on this key. If this is the case, the software-based system transmits to the user a string encoded using the first public key, which the user decodes using his/her private key and encodes using a key of the service server and subsequently transmits back to the service server. If the string transmitted is identical to the string received, the software-based system recognizes the user as being authenticated.