###### Abstract  
The NFC and MIFARE systems (referred to as HF-band RFID) are a special case of Radio Frequency Identification (RFID) technology using a radio frequency of 13.56 MHz for communication. The declared range of such communication is usually several cm and is characterized by the need to bring the data carrier close to the system reader. Due to the possibility of transmitting sensitive data in this type of system, an important problem seems to be the electromagnetic security of the transmitted data between the cards (tags) and the reader and within the system. In most of the available research studies, the security of RFID systems comes down to the analysis of the effectiveness of encryption of transmitted data or testing the range of communication between the reader and the identifier. In this research, however, special attention is paid to the so-called electromagnetic information security without the analysis of cryptographic protection. In some cases (e.g., data retransmission), encryption may not be an effective method of securing data (because, e.g., encrypted data might be used to open and start a car with a keyless system). In addition, the research draws attention to the fact that the data from the identifier can be accessed not only from the identifier, but also from the control system (reader, wiring, controller, etc.) from which the data can be radiated (unintentionally) at a much greater distance than the communication range between the identifier and the reader. In order to determine the security of the transmitted data in the HF-band RFID systems, a number of tests were carried out with the use of specialized equipment. During the measurements, both the data carriers themselves (cards, key fobs, stickers, tags) and exemplary systems for reading data from the media (a writable card reader, a mobile phone with NFC function, and an extensive access control system) were tested. The experiments carried out made it possible to determine the safety of NFC and MIFARE systems during their use and only storage (e.g., the ability to read data from an identification card stored in a pocket).  
a 2024 14 5854 10.3390/app1435854 10.  
* Health care [5];
* Monitoring the strain condition of critical structures [6; 7];
* Tickets to events such as concerts;
* Loyalty programs;
* Campus cards;
* Tolls (vignettes);
* Parking management
* Internet of Things (IoT).  
The operation of these systems involves the transmission of data between the identifier and the individual elements of the control system. It is the data transmission process that can pose a great threat to the security of the transmitted data, which may include personal data, identification numbers, medical data, permits to enter controlled access areas, etc. Such data can then be used, for example, to forge the original identifier or directly transmit data to terminals without the cardholder's knowledge.  
Among the most important risks associated with the use of NFC or MIFARE (this applies to virtually every RFID standard) are the following [8; 9]:  
* Interception of transmissions and copying of data to another medium or use of such data for a specific purpose;
* Transmission of data from an identifier located at a large distance from the reader using an additional transmission channel (so-called theft by a suitcase);
* Blocking the system by generating a high-power signal in the frequency band used by the system.  
The results of the research presented in the following part of the article and the conclusions resulting from them do not take into account the software security measures used, such as encryption of transmitted information. They primarily concern the aspect of electromagnetic information penetration, i.e., the possibility of receiving an electromagnetic emission correlated with the transmitted information at any point of the system used (e.g., ID, reader, controller, wiring, etc.).