Abstract: A method for authenticating a trusted user interface of a first user terminal which incorporates a scan function, comprising the steps a) installing an app that provides the trusted user interface which contains a private and public key pair of a first asymmetric cryptosystem and opening the app on the first user terminal, b) opening a dedicated web page on a second user terminal and inputting a self-chosen certificate of authenticity in an open web session on the web page which likewise contains a private and public key pair of the first cryptosystem, c) generating and displaying a graphic code on a display screen of the second user terminal via the web session of the dedicated web page, d) scanning the graphic code displayed on the second user terminal into the app by means of the first user terminal, e) identifying the web session of the dedicated web page with the app based on the graphic code and logging into same via the first user terminal, f) mutually authenticating and establishing of an encrypted c

Abstract: A method for transmitting transaction data using a public data network, comprising the steps of: transmitting primary transaction data from a provider data base via the public data network to a display device connected to the data network and, locally, visually and/or acoustically displaying the primary transaction data thereon, in particular visually on a displayed provider website as bar code or QR code, b1) recording the display and generating a primary transaction file in a user terminal of an access network, or b2) recording the display and generating a primary transaction file in a recording device and then transmitting the primary transaction file to a user terminal of an access network, via a wireless near field data transmitter of the recording device and user terminal, processing the primary transaction file on the user terminal for extracting at least a part of the transaction data, and generating an extract file, inputting an authorization data set of a debit or credit card configured as a smar