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: "hvacker bridging the air gap by attacking the air conditioning system"
  Abstract: Modern corporations physically separate their sensitive computational infrastructure from public or other accessible networks in order to prevent cyber-attacks. However, attackers still manage to infect these networks, either by means of an insider or by infiltrating the supply chain. Therefore, an attacker's main challenge is to determine a way to command and control the compromised hosts that are isolated from an accessible network (e.g., the Internet). #R##N#In this paper, we propose a new adversarial model that shows how an air gapped network can receive communications over a covert thermal channel. Concretely, we show how attackers may use a compromised air-conditioning system (connected to the internet) to send commands to infected hosts within an air-gapped network. Since thermal communication protocols are a rather unexplored domain, we propose a novel line-encoding and protocol suitable for this type of channel. Moreover, we provide experimental results to demonstrate the covert channel's feasibility, and to calculate the channel's bandwidth. Lastly, we offer a forensic analysis and propose various ways this channel can be detected and prevented. #R##N#We believe that this study details a previously unseen vector of attack that security experts should be aware of.

Connected through hyperedge HE-1 (induced by source paper "leveraging operational technology and the internet of things to attack smart buildings"):
  with members:
    - "the security of smart buildings a systematic literature review"

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)