In a method in a portable end device (10), data (70E) received from an external data processing device (100), edited according to a communication protocol stack and thereby cryptographically secured according to a security protocol (32), is processed. According to the invention, the received data (70E) is processed according to the communication protocols (22; 24; 26) of the communication protocol stack underneath the security protocol (32) in an unsecured data processing environment (14) of the terminal (10) and processed at least according to the security protocol (32) in a secured data processing environment (16) of the terminal (10).
