The Analysis Of Mifare Contactless IC Card Security

The Mifare Classic is a reliable and safe contactless smart card that is widely used in accesscontrol for office buildings, payment systems for public transport, and other applications. Sinceintroduced by NXP company in 1994, this system has been considered to be a very excellentcontactless smart card technology. Its core algorithms about security, including the authenticationprotocol, the symmetric cipher, and the generation of pseudo-random are kept secret by itsmanufacturer. These algorithms are able to protect the communication between the card and thereader and can guarantee the security of the system.However, unfortunately the complex protocols and algorithms of the Mifare Classic systemstill have weaknesses which attacker can exploit to retrieve the secret key of the card. By analyzingthe communication protocol and the encryption algorithms of the Mifare Classic system,we studyabout its issues of the security deeply. this paper has mainly accomplished the research as follows:（1）Describe some design weaknesses of the Mifare Classic. These weaknesses allow us torecover the secret key of the card in two different ways: eavesdropping and communicating with acard as reader. In the first way, attacker need to eavesdrop the communication between the card andreader and gather their authentication data which can be used to recover the secret key. In thesecond way, attacker communicates with card directly as a reader and recover the secret key bysearching the parity bits, varying {nR},varying nTand nested authentication.（2）Design a system which can implement eavesdropping with the M1 card and describe itshardware circuit and software design. In the system, the eavesdropped signals received through anantenna is filtered and demodulated and then converted to digital signals by the high speed ADC.These digital signals need to be decoded by STM32-FPGA co-processing module and finally beuploaded to the PC to show or recover the secret key. The STM32 and FPGA are designed tocommunication through the SPI bus, the PC and STM32 are designed to communication throughthe USB. The software of the whole system is divided into three sections:the Verilog programs ofFPGA, the C programs of STM32 and the C++ programs of PC.（3）From the perspective of technology and management, some security suggestions areproposed. The attacker can implement state restoration and cloning using the recovered secret key.Therefore, some measures which can prevent these two applications are given and the measuresshould be low cost and don’t affect the normal use.From the study and analysis to the Mifare Classic system, we believe that the communicationprotocol and the encryption algorithms can guarantee the security of system to a certain extent. However, the Mifare Classic system will have potential safety hazard as the emergence of moredesign weaknesses.