human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "climex a wireless physical layer security protocol based on clocked impulse exchanges"):
  Abstract: A novel method and protocol establishing common secrecy based on physical parameters between two users is proposed. The four physical parameters of users are their clock frequencies, their relative clock phases and the distance between them. The protocol proposed between two users is backed by theoretical model for the measurements. Further, estimators are proposed to estimate secret physical parameters. Physically exchanged parameters are shown to be secure by virtue of their non-observability to adversaries. Under a simplified analysis based on a testbed settings, it is shown that 38 bits of common secrecy can be derived for one run of the proposed protocol among users. The method proposed is also robust against various kinds of active timing attacks and active impersonating adversaries.

Includes members:
  Member "scalable and passive wireless network clock synchronization in los environments":
    also connected through other hyperedges:
      (none)
  Member "device fingerprinting in wireless networks challenges and opportunities":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "prifi low latency anonymity for organizational networks")
  Member "pairwise secret key agreement based on location derived common randomness":
    also connected through other hyperedges:
      (none)
  Member "distributed inference in the presence of eavesdroppers a survey":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "remote state estimation over packet dropping links in the presence of an eavesdropper")
  Member "joint ranging and clock parameter estimation by wireless round trip time measurements":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "scalable and passive wireless network clock synchronization in los environments")
  Member "principles of physical layer security in multiuser wireless networks a survey":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "angle aware user cooperation for secure massive mimo in rician fading channel")
  Member "using the physical layer for wireless authentication in time variant channels":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "on the effective capacity of an underwater acoustic channel under impersonation attack")
  Member "secure vehicular communication systems design and architecture":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "scaling pseudonymous authentication for large mobile systems")

Question: Please tell me which class the source paper 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)