Computer
system comprising a terminal (186), a service computer
system (150), a user computer
system (100), an ID provider computer system (136), and an ID token (106) assigned to a user (102), wherein the ID token has an
electronic memory (118) with a protected memory area (124) in which one or more attributes are stored, wherein access to the protected memory area is possible only via a processor (128) of the ID token, and wherein the ID token has a
communication interface (108) for communication with a reader of a user computer system (100), wherein the terminal, the service computer system, the user computer system, the ID provider computer system, and the ID token are configured to perform the following steps: - Display of an optically readable pattern on a screen (188) of a terminal (186), wherein the optically readable pattern contains encoded information which includes at least a
logical address of a service computer system (150) and
transaction data, - Detection of the pattern using an optical sensor (190) of the user computer system and decoding of the pattern by the user computer system, - Transmission of a transaction request (158) from the user computer system to the
logical address of the service computer system over the network, wherein the transaction request includes the
transaction data, - Transmission of a request (166) from the service computer system via the user computer system (100) to an ID provider computer system (136), wherein the transmission takes place over the network, wherein the request includes an attribute specification of the attributes to be read from the ID token for the execution of the transaction, -
User authentication against the ID token, -
Authentication of the ID provider computer system to the ID token over the network, - provided that the user and the ID provider computer system are successfully authenticated to the ID token, the ID provider computer system reads the attribute(s) from the ID token according to the attribute specification over the network with end-to-end
encryption, - Transmission of a response (174) from the ID provider computer system via the user computer system to the service computer system, wherein the transmission of the response takes place over the network, wherein the response includes the read attribute(s), and wherein the response is signed by the ID provider computer system, - Execution of the transaction using the
transaction data and the attribute(s) by the service computer system, wherein the terminal is a
machine, wherein the transaction data includes a
payment amount, and wherein the transaction is initiated by the service computer system to carry out a
financial transaction in the amount of the
payment.