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: "compchall addressing password guessing attacks"
  Abstract: Even though passwords are the most convenient means of authentication, they bring along themselves the threat of dictionary attacks. Dictionary attacks may be of two kinds: online and offline. While offline dictionary attacks are possible only if the adversary is able to collect data for a successful protocol execution by eavesdropping on the communication channel and can be successfully countered using public key cryptography, online dictionary attacks can be performed by anyone and there is no satisfactory solution to counter them. This paper presents a new authentication protocol which is called CompChall (computational challenge). The proposed protocol uses only one way hash functions as the building blocks and attempts to eliminate online dictionary attacks by implementing a challenge-response system. This challenge-response system is designed in a fashion that it does not pose any difficulty to a genuine user but is time consuming and computationally intensive for an adversary trying to launch a large number of login requests per unit time as in the case of an online dictionary attack. The protocol is stateless and thus less vulnerable to DoS (Denial of Service) attacks.

Connected through hyperedge HE-1 (induced by source paper "increasing security in cloud environment"):
  with members:
    - "rism reputation based intrusion detection system for mobile ad hoc networks"
    - "detection and prevention of botnets and malware in an enterprise network"
    - "a paxos based state machine replication system for anomaly detection"
    - "a multi dimensional approach towards intrusion detection system"
    - "a hybrid approach towards intrusion detection based on artificial immune system and soft computing"
    - "a survey on security issues in cloud computing"
    - "a new trusted and collaborative agent based approach for ensuring cloud security"
    - "grid security and integration with minimal performance degradation"

Connected through hyperedge HE-2 (induced by source paper "cloud computing an approach with modern cryptography"):
  with members:
    - "rism reputation based intrusion detection system for mobile ad hoc networks"
    - "increasing security in cloud environment"
    - "a semi distributed reputation based intrusion detection system for mobile adhoc networks"

Connected through hyperedge HE-3 (induced by source paper "data hiding and retrieval using permutation index method"):
  with members:
    - "survey on security issues in cloud computing and associated mitigation techniques"

Connected through hyperedge HE-4 (induced by source paper "a heuristic reputation based system to detect spam activities in a social networking platform hrsssnp"):
  with members:
    - "rism reputation based intrusion detection system for mobile ad hoc networks"
    - "survey on security issues in cloud computing and associated mitigation techniques"
    - "a new trusted and collaborative agent based approach for ensuring cloud security"
    - "security scheme for distributed dos in mobile ad hoc networks"
    - "a semi distributed reputation based intrusion detection system for mobile adhoc networks"

Connected through hyperedge HE-5 (induced by source paper "survey on security issues in cloud computing and associated mitigation techniques"):
  with members:
    - "a multi factor security protocol for wireless payment secure web authentication using mobile devices"
    - "a novel multipath approach to security in mobile ad hoc networks manets"
    - "a new trusted and collaborative agent based approach for ensuring cloud security"

Connected through hyperedge HE-6 (induced by source paper "prover and verifier based password protection pvbpp"):
  with members:
    - "rism reputation based intrusion detection system for mobile ad hoc networks"

Connected through hyperedge HE-7 (induced by source paper "a survey on security issues in cloud computing"):
  with members:
    - "a multi factor security protocol for wireless payment secure web authentication using mobile devices"
    - "a new trusted and collaborative agent based approach for ensuring cloud security"
    - "an lsb data hiding technique using natural number decomposition"

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)