human: Given a node-centered hypergraph: <hypergraph>, where nodes represent papers and hyperedges represent sets of papers co-cited by a source paper.

Details of the hypergraph:
Center node: "data exfiltration via multipurpose rfid cards and countermeasures"
  Abstract: Radio-frequency identification(RFID) technology is widely applied in daily human life. The RFID cards are seen everywhere, from entrance guard to consumption. The information security of RFID cards, such as data confidentiality, tag anonymity, mutual authentication etc, has been fully studied. In the paper, using the RFID cards in MIFARE Classic and DESFire families, a bidirectional covert channel via multipurpose RFID cards between service providers is built to leak sensitive data between two simulation systems. Furthermore, by calculations and experiments, the daily channel capacity to leak data of the channel is obtained. Although the storage capacity of a single RFID card is very small, a large user base can still bring about a considerable amount to leak data. Then, the reasons for the existence of such channels are discussed. To eliminate this type of covert channels, a new authentication protocol between RFID cards and card readers are proposed. Our experimental results show a significant security improvement in prevention of such covert communications while keeping user convenience.

Connected through hyperedge HE-1 (induced by source paper "brightness leaking sensitive data from air gapped workstations via screen brightness"):
  with members:
    - "ctrl alt led leaking data from air gapped computers via keyboard leds"
    - "optical tempest"
    - "powerhammer exfiltrating data from air gapped computers through power lines"
    - "magneto covert channel between air gapped systems and nearby smartphones via cpu generated magnetic fields"
    - "usbee air gap covert channel via electromagnetic emission from usb"
    - "fansmitter acoustic data exfiltration from speakerless air gapped computers"
    - "visisploit an optical covert channel to leak data through an air gap"
    - "bitwhisper covert signaling channel between air gapped computers using thermal manipulations"

Connected through hyperedge HE-2 (induced by source paper "powerhammer exfiltrating data from air gapped computers through power lines"):
  with members:
    - "optical exfiltration of data via keyboard led status indicators to ip cameras"
    - "optical tempest"
    - "odini escaping sensitive data from faraday caged air gapped computers via magnetic fields"
    - "magneto covert channel between air gapped systems and nearby smartphones via cpu generated magnetic fields"
    - "mosquito covert ultrasonic transmissions between two air gapped computers using speaker to speaker communication"
    - "air jumper covert air gap exfiltration infiltration via security cameras infrared ir"
    - "xled covert data exfiltration from air gapped networks via router leds"
    - "usbee air gap covert channel via electromagnetic emission from usb"

Question: Please tell me which class the center node belongs to. The 40 classes are: cs.NA(Numerical Analysis), cs.MM(Multimedia), cs.LO(Logic in Computer Science), cs.CY(Computers and Society), cs.CR(Cryptography and Security), cs.DC(Distributed, Parallel, and Cluster Computing), cs.HC(Human-Computer Interaction), cs.CE(Computational Engineering, Finance, and Science), cs.NI(Networking and Internet Architecture), cs.CC(Computational Complexity), cs.AI(Artificial Intelligence), cs.MA(Multiagent Systems), cs.GL(General Literature), cs.NE(Neural and Evolutionary Computing), cs.SC(Symbolic Computation), cs.AR(Hardware Architecture), cs.CV(Computer Vision and Pattern Recognition), cs.GR(Graphics), cs.ET(Emerging Technologies), cs.SY(Systems and Control), cs.CG(Computational Geometry), cs.OH(Other Computer Science), cs.PL(Programming Languages), cs.SE(Software Engineering), cs.LG(Machine Learning), cs.SD(Sound), cs.SI(Social and Information Networks), cs.RO(Robotics), cs.IT(Information Theory), cs.PF(Performance), cs.CL(Computation and Language), cs.IR(Information Retrieval), cs.MS(Mathematical Software), cs.FL(Formal Languages and Automata Theory), cs.DS(Data Structures and Algorithms), cs.OS(Operating Systems), cs.GT(Computer Science and Game Theory), cs.DB(Databases), cs.DL(Digital Libraries), cs.DM(Discrete Mathematics). Directly output the class name.

gpt: cs.CR(Cryptography and Security)