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: "design and implementation of a network security management system"
  Abstract: In recent years, the emerged network worms and attacks have distributive characteristic, which can spread globally in a very short time. Security management crossing network to co-defense network-wide attacks and improve efficiency of security administration is urgently needed. This paper proposes a hierarchical distributed network security management system (HD-NSMS), which can centrally manage security across networks. First describes the system in macrostructure and microstructure; then discusses three key problems when building HD-NSMS: device model, alert mechanism and emergency response mechanism; at last, describes the implementation of HD-NSMS. The paper is valuable for implementing NSMS in that it derives from a practical network security management system (NSMS).

Connected through hyperedge HE-1 (induced by source paper "duplication of windows services"):
  with members:
    - "virtualizing system and ordinary services in windows based os level virtual machines"
    - "a study on altering postgresql from multi processes structure to multi threads structure"
    - "implementing rbac model in an operating system kernel"
    - "suspicious taint based access control for protecting os from network attacks"
    - "compatible and usable mandatory access control for good enough os security"

Connected through hyperedge HE-2 (induced by source paper "confining windows inter process communications for os level virtual machine"):
  with members:
    - "virtualizing system and ordinary services in windows based os level virtual machines"
    - "a study on altering postgresql from multi processes structure to multi threads structure"
    - "implementing rbac model in an operating system kernel"
    - "suspicious taint based access control for protecting os from network attacks"

Connected through hyperedge HE-3 (induced by source paper "suspicious taint based access control for protecting os from network attacks"):
  with members:
    - "virtualizing system and ordinary services in windows based os level virtual machines"
    - "a study on altering postgresql from multi processes structure to multi threads structure"
    - "implementing rbac model in an operating system kernel"
    - "compatible and usable mandatory access control for good enough os security"

Connected through hyperedge HE-4 (induced by source paper "virtualizing system and ordinary services in windows based os level virtual machines"):
  with members:
    - "a study on altering postgresql from multi processes structure to multi threads structure"
    - "implementing rbac model in an operating system kernel"
    - "suspicious taint based access control for protecting os from network attacks"

Connected through hyperedge HE-5 (induced by source paper "a study on altering postgresql from multi processes structure to multi threads structure"):
  with members:
    - "implementing rbac model in an operating system kernel"
    - "suspicious taint based access control for protecting os from network attacks"
    - "compatible and usable mandatory access control for good enough os security"

Connected through hyperedge HE-6 (induced by source paper "implementing rbac model in an operating system kernel"):
  with members:
    - "a study on altering postgresql from multi processes structure to multi threads structure"

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)