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: "enhanced usage of keys obtained by physical unconditionally secure distributions"
  Abstract: Unconditionally secure physical key distribution schemes are very slow, and it is practically impossible to use a one-time-pad based cipher to guarantee unconditional security for the encryption of data because using the key bits more than once gives out statistical information, for example via the known-plain-text-attack or by utilizing known components of the protocol and language statistics. Here, we outline a protocol that reduces this speed problem and allows almost-one-time-pad based communication with an unconditionally secure physical key of finite length. The physical, unconditionally secure key is not used for data encryption but is employed in order to generate and share a new software-based key without any known-plain-text component. The software-only-based key distribution is then changed from computationally secure to unconditionally secure, because the communicated key-exchange data (algorithm parameters, one-way functions of random numbers, etc.) are encrypted in an unconditionally secure way with a one-time-pad. For practical applications, this combined physical/software key distribution based communication looks favorable compared to the software-only and physical-only key distribution based communication whenever the speed of the physical key distribution is much lower than that of the software-based key distribution. A mathematical security proof of this new scheme remains an open problem.

Connected through hyperedge HE-1 (induced by source paper "current injection attack against the kljn secure key exchange"):
  with members:
    - "random resistor random temperature kirchhoff law johnson noise rrrt kljn key exchange"
    - "comments on a new transient attack on the kish key distribution system"
    - "resource requirements and speed versus geometry of unconditionally secure physical key exchanges"
    - "key exchange trust evaluation in peer to peer sensor networks with unconditionally secure key exchange"
    - "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"
    - "generalized kirchhoff law johnson noise kljn secure key exchange system using arbitrary resistors"
    - "cable capacitance attack against the kljn secure key exchange"

Connected through hyperedge HE-2 (induced by source paper "key exchange trust evaluation in peer to peer sensor networks with unconditionally secure key exchange"):
  with members:
    - "resource requirements and speed versus geometry of unconditionally secure physical key exchanges"
    - "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"

Connected through hyperedge HE-3 (induced by source paper "on kljn based secure key distribution in vehicular communication networks"):
  with members:
    - "current and voltage based bit errors and their combined mitigation for the kirchhoff law johnson noise secure key exchange"
    - "on the security of the kirchhoff law johnson noise kljn communicator"
    - "securing vehicle communication systems by the kljn key exchange protocol"
    - "information theoretically secure enhanced johnson noise based key distribution over the smart grid with switched filters"
    - "errors and their mitigation at the kirchhoff law johnson noise secure key exchange"
    - "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"
    - "secure vehicular communication systems design and architecture"

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)