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: "sound proof usable two factor authentication based on ambient sound"
  Abstract: Two-factor authentication protects online accounts even if passwords are leaked. Most users, however, prefer password-only authentication. One reason why two-factor authentication is so unpopular is the extra steps that the user must complete in order to log in. Currently deployed two-factor authentication mechanisms require the user to interact with his phone to, for example, copy a verification code to the browser. Two-factor authentication schemes that eliminate user-phone interaction exist, but require additional software to be deployed. #R##N#In this paper we propose Sound-Proof, a usable and deployable two-factor authentication mechanism. Sound-Proof does not require interaction between the user and his phone. In Sound-Proof the second authentication factor is the proximity of the user's phone to the device being used to log in. The proximity of the two devices is verified by comparing the ambient noise recorded by their microphones. Audio recording and comparison are transparent to the user, so that the user experience is similar to the one of password-only authentication. Sound-Proof can be easily deployed as it works with current phones and major browsers without plugins. We build a prototype for both Android and iOS. We provide empirical evidence that ambient noise is a robust discriminant to determine the proximity of two devices both indoors and outdoors, and even if the phone is in a pocket or purse. We conduct a user study designed to compare the perceived usability of Sound-Proof with Google 2-Step Verification. Participants ranked Sound-Proof as more usable and the majority would be willing to use Sound-Proof even for scenarios in which two-factor authentication is optional.

Connected through hyperedge HE-1 (induced by source paper "short range audio channels security survey of mechanisms applications and research challenges"):
  with members:
    - "perils of zero interaction security in the internet of things"
    - "a survey on context based co presence detection techniques"
    - "doubleecho mitigating context manipulation attacks in copresence verification"
    - "survey and systematization of secure device pairing"
    - "continuous authentication for voice assistants"
    - "dolphinattack inaudible voice commands"
    - "a survey on homomorphic encryption schemes theory and implementation"
    - "don t skype type acoustic eavesdropping in voice over ip"

Connected through hyperedge HE-2 (induced by source paper "perils of zero interaction security in the internet of things"):
  with members:
    - "on the secrecy of publicly observable biometric features security properties of gait for mobile device pairing"
    - "survey and systematization of secure device pairing"
    - "re run repeat reproduce reuse replicate transforming code into scientific contributions"
    - "demo of bandana body area network device to device authentication using natural gait"
    - "walk unlock zero interaction authentication protected with multi modal gait biometrics"
    - "the internet of things new interoperability management and security challenges"
    - "context aware computing for the internet of things a survey"

Connected through hyperedge HE-3 (induced by source paper "a survey on context based co presence detection techniques"):
  with members:
    - "6thsense a context aware sensor based attack detector for smart devices"
    - "location cheating a security challenge to location based social network services"

Connected through hyperedge HE-4 (induced by source paper "proximity verification based on acoustic room impulse response"):
  with members:
    - "contextual proximity detection in the face of context manipulating adversaries"
    - "soundloc acoustic method for indoor localization without infrastructure"

Connected through hyperedge HE-5 (induced by source paper "a secure mobile authentication alternative to biometrics"):
  with members:
    - "video liveness for citizen journalism attacks and defenses"
    - "camera based two factor authentication through mobile and wearable devices"
    - "yfcc100m the new data in multimedia research"
    - "tensorflow a system for large scale machine learning"
    - "armageddon cache attacks on mobile devices"
    - "unsupervised representation learning with deep convolutional generative adversarial networks"
    - "deep representations for iris face and fingerprint spoofing detection"
    - "rethinking the inception architecture for computer vision"

Connected through hyperedge HE-6 (induced by source paper "comparative analysis and framework evaluating mimicry resistant and invisible web authentication schemes"):
  with members:
    - "waca wearable assisted continuous authentication"
    - "identification of wearable devices with bluetooth"
    - "mobile device identification via sensor fingerprinting"
    - "touchalytics on the applicability of touchscreen input as a behavioral biometric for continuous authentication"

Connected through hyperedge HE-7 (induced by source paper "camera based two factor authentication through mobile and wearable devices"):
  with members:
    - "implicit sensor based authentication of smartphone users with smartwatch"
    - "rethinking the inception architecture for computer vision"

Connected through hyperedge HE-8 (induced by source paper "stash securing transparent authentication schemes using prover side proximity verification"):
  with members:
    - "contextual proximity detection in the face of context manipulating adversaries"
    - "mining users significant driving routes with low power sensors"

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)