In an approach for authenticating a user computer, connectable to a mobile network, a computer retrieves an attribute credential, the attribute credential certifying a set of user attributes and a device identifier for identifying the user computer to the mobile network. The computer requests a location credential, the location credential certifying a device identifier and location data indicating a current location of the user computer determined by the mobile network. Additionally, the computer produces an authentication token comprising the attribute credential, the location credential, the location data, and a proof for proving that the device identifier in the attribute credential equals the device identifier in the location credential. Furthermore, the computer sends the authentication token for authentication.