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 survey of attacks security mechanisms and challenges in wireless sensor networks"
  Abstract: Wireless Sensor networks (WSN) is an emerging technology and have great potential to be employed in critical situations like battlefields and commercial applications such as building, traffic surveillance, habitat monitoring and smart homes and many more scenarios. One of the major challenges wireless sensor networks face today is security. While the deployment of sensor nodes in an unattended environment makes the networks vulnerable to a variety of potential attacks, the inherent power and memory limitations of sensor nodes makes conventional security solutions unfeasible. The sensing technology combined with processing power and wireless communication makes it profitable for being exploited in great quantity in future. The wireless communication technology also acquires various types of security threats. This paper discusses a wide variety of attacks in WSN and their classification mechanisms and different securities available to handle them including the challenges faced.

Connected through hyperedge HE-1 (induced by source paper "security of the internet of things vulnerabilities attacks and countermeasures"):
  with members:
    - "security implications of fog computing on the internet of things"
    - "a survey on sensor based threats to internet of things iot devices and applications"
    - "understanding iot security through the data crystal ball where we are now and where we are going to be"
    - "spying on the smart home privacy attacks and defenses on encrypted iot traffic"
    - "survey of security and privacy issues of internet of things"
    - "trail topology authentication in rpl"
    - "security in wireless sensor networks issues and challenges"

Connected through hyperedge HE-2 (induced by source paper "reliability analysis to overcome black hole attack in wireless sensor network"):
  with members:
    - "security in wireless sensor networks issues and challenges"

Connected through hyperedge HE-3 (induced by source paper "attacks and counterattacks on wireless sensor networks"):
  with members:
    - "a comparison of link layer attacks on wireless sensor networks"

Connected through hyperedge HE-4 (induced by source paper "study of a new link layer security scheme in a wireless sensor network"):
  with members:
    - "flexisec a configurable link layer security architecture for wireless sensor networks"

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)