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: "exploring opportunistic execution for integrating security into legacy hard real time systems"
  Abstract: Due to physical isolation as well as use of proprietary hardware and protocols, traditional real-time systems (RTS) were considered to be invulnerable to security breaches and external attacks. However, this assumption is being challenged by recent attacks that highlight the vulnerabilities in such systems. In this paper, we focus on integrating security mechanisms into RTS (especially legacy RTS) and provide a metric to measure the effectiveness of such mechanisms. We combine opportunistic execution with hierarchical scheduling to maintain compatibility with legacy systems while still providing flexibility. The proposed approach is shown to increase the security posture of RTS systems without impacting their temporal constraints.

Connected through hyperedge HE-1 (induced by source paper "on scheduler side channels in dynamic priority real time systems"):
  with members:
    - "a novel side channel in real time schedulers"
    - "mitigating timing side channel in shared schedulers"
    - "quantifying the information leakage in timing side channels in deterministic work conserving schedulers"

Connected through hyperedge HE-2 (induced by source paper "period adaptation for continuous security monitoring in multicore real time systems"):
  with members:
    - "securing real time internet of things"
    - "contego an adaptive framework for integrating security tasks in real time systems"
    - "partitioned multiprocessor fixed priority scheduling of sporadic real time tasks"

Connected through hyperedge HE-3 (induced by source paper "protecting actuators in safety critical iot systems from control spoofing attacks"):
  with members:
    - "securing real time internet of things"
    - "contego an adaptive framework for integrating security tasks in real time systems"

Connected through hyperedge HE-4 (induced by source paper "securing real time internet of things"):
  with members:
    - "contego an adaptive framework for integrating security tasks in real time systems"
    - "mitigating timing side channel in shared schedulers"
    - "internet of things iot a vision architectural elements and future directions"

Connected through hyperedge HE-5 (induced by source paper "integrating security in resource constrained cyber physical systems"):
  with members:
    - "coding schemes for securing cyber physical systems against stealthy data injection attacks"

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)