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: "shoulder surfing attack in graphical password authentication"
  Abstract: Information and computer security is supported largely by passwords which are the principle part of the authentication process. The most common computer authentication method is to use alphanumerical username and password which has significant drawbacks. To overcome the vulnerabilities of traditional methods, visual or graphical password schemes have been developed as possible alternative solutions to text-based scheme. A potential drawback of graphical password schemes is that they are more vulnerable to shoulder surfing than conventional alphanumeric text passwords. When users input their passwords in a public place, they may be at risk of attackers stealing their password. An attacker can capture a password by direct observation or by recording the individual's authentication session. This is referred to as shoulder- surfing and is a known risk, of special concern when authenticating in public places. In this paper we will present a survey on graphical password schemes from 2005 till 2009 which are proposed to be resistant against shoulder surfing attacks.

Connected through hyperedge HE-1 (induced by source paper "brightness leaking sensitive data from air gapped workstations via screen brightness"):
  with members:
    - "ctrl alt led leaking data from air gapped computers via keyboard leds"
    - "data exfiltration via multipurpose rfid cards and countermeasures"
    - "optical tempest"
    - "powerhammer exfiltrating data from air gapped computers through power lines"
    - "magneto covert channel between air gapped systems and nearby smartphones via cpu generated magnetic fields"
    - "usbee air gap covert channel via electromagnetic emission from usb"
    - "fansmitter acoustic data exfiltration from speakerless air gapped computers"
    - "visisploit an optical covert channel to leak data through an air gap"

Connected through hyperedge HE-2 (induced by source paper "shoulder surfing from an experimental study to a comparative framework"):
  with members:
    - "illusionpin shoulder surfing resistant authentication using hybrid images"
    - "towards baselines for shoulder surfing on mobile authentication"

Connected through hyperedge HE-3 (induced by source paper "visisploit an optical covert channel to leak data through an air gap"):
  with members:
    - "fansmitter acoustic data exfiltration from speakerless air gapped computers"
    - "bitwhisper covert signaling channel between air gapped computers using thermal manipulations"
    - "on covert acoustical mesh networks in air"
    - "airhopper bridging the air gap between isolated networks and mobile phones using radio frequencies"

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)