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: "a directional coupler attack against the kish key distribution system"
  Abstract: The Kish key distribution system has been proposed as a class ical alternative to quantum key distribution. The idealized Kish scheme elegantly promise s secure key distribution by exploiting thermal noise in a transmission line. However, we demonstrate that it is vulnerable to nonidealities in its components, such as the finite resistance of the transmission line connecting its endpoints. We introduce a novel attack against this nonideality using directional wave measurements, and experimentally demonstrate its efficacy. Our attack is based on causality: in a spatially distributed system, propagation is needed for thermodynamic equilibration, and that leaks information.

Connected through hyperedge HE-1 (induced by source paper "resource requirements and speed versus geometry of unconditionally secure physical key exchanges"):
  with members:
    - "analysis of an attenuator artifact in an experimental attack by gunn allison abbott against the kirchhoff law johnson noise kljn secure key exchange system"
    - "on kljn based secure key distribution in vehicular communication networks"
    - "what kind of noise guarantees security for the kirchhoff law johnson noise key exchange"
    - "on the security of the kirchhoff law johnson noise kljn communicator"
    - "securing vehicle communication systems by the kljn key exchange protocol"
    - "noise properties in the ideal kirchhoff law johnson noise secure communication system"
    - "on the cracking scheme in the paper a directional coupler attack against the kish key distribution system by gunn allison and abbott"
    - "elimination of a second law attack and all cable resistance based attacks in the kirchhoff law johnson noise kljn secure key exchange system"

Connected through hyperedge HE-2 (induced by source paper "on the cracking scheme in the paper a directional coupler attack against the kish key distribution system by gunn allison and abbott"):
  with members:
    - "what kind of noise guarantees security for the kirchhoff law johnson noise key exchange"
    - "noise properties in the ideal kirchhoff law johnson noise secure communication system"
    - "do electromagnetic waves exist in a short cable at low frequencies what does physics say"
    - "enhanced secure key exchange systems based on the johnson noise scheme"
    - "critical analysis of the bennett riedel attack on secure cryptographic key distributions via the kirchhoff law johnson noise scheme"
    - "effective privacy amplification for secure classical communications"

Connected through hyperedge HE-3 (induced by source paper "do electromagnetic waves exist in a short cable at low frequencies what does physics say"):
  with members:
    - "on the security of the kirchhoff law johnson noise kljn communicator"
    - "critical analysis of the bennett riedel attack on secure cryptographic key distributions via the kirchhoff law johnson noise scheme"

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)