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: "security for grid services"
  Abstract: Grid computing is concerned with the sharing and coordinated use of diverse resources in distributed "virtual organizations." The dynamic and multi-institutional nature of these environments introduces challenging security issues that demand new technical approaches. In particular, one must deal with diverse local mechanisms, support dynamic creation of services, and enable dynamic creation of trust domains. We describe how these issues are addressed in two generations of the Globus Toolkit. First, we review the Globus Toolkit version 2 (GT2) approach; then, we describe new approaches developed to support the Globus Toolkit version 3 (GT3) implementation of the Open Grid Services Architecture, an initiative that is recasting Grid concepts within a service oriented framework based on Web services. GT3's security implementation uses Web services security mechanisms for credential exchange and other purposes, and introduces a tight least-privilege model that avoids the need for any privileged network service.

Connected through hyperedge HE-1 (induced by source paper "scitokens capability based secure access to remote scientific data"):
  with members:
    - "data access for ligo on the osg"
    - "flexible session management in a distributed environment"

Connected through hyperedge HE-2 (induced by source paper "dotdfs a grid based high throughput file transfer system"):
  with members:
    - "dotgrid a net based cross platform software for desktop grids"
    - "the anatomy of the grid enabling scalable virtual organizations"

Connected through hyperedge HE-3 (induced by source paper "grid security and integration with minimal performance degradation"):
  with members:
    - "a community authorization service for group collaboration"
    - "the anatomy of the grid enabling scalable virtual organizations"

Connected through hyperedge HE-4 (induced by source paper "a novel trigon based dual authentication protocol for enhancing security in grid environment"):
  with members:
    - "the anatomy of the grid enabling scalable virtual organizations"

Connected through hyperedge HE-5 (induced by source paper "mobile computing in physics analysis an indicator for escience"):
  with members:
    - "distributed analysis and load balancing system for grid enabled analysis on hand held devices using multi agents systems"
    - "the clarens web services architecture"
    - "clarens client and server applications"

Connected through hyperedge HE-6 (induced by source paper "the earth system grid supporting the next generation of climate modeling research"):
  with members:
    - "a community authorization service for group collaboration"

Connected through hyperedge HE-7 (induced by source paper "a grid enabled interface to condor for interactive analysis on handheld and resource limited devices"):
  with members:
    - "the clarens web services architecture"
    - "clarens client and server applications"

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)