human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "secure and energy efficient data aggregation in wireless sensor networks"):
  Abstract: Data aggregation in intermediate nodes (called aggregator nodes) is an effective approach for optimizing consumption of scarce resources like bandwidth and energy in Wireless Sensor Networks (WSNs). However, in-network processing poses a problem for the privacy of the sensor data since individual data of sensor nodes need to be known to the aggregator node before the aggregation process can be carried out. In applications of WSNs, privacy-preserving data aggregation has become an important requirement due to sensitive nature of the sensor data. Researchers have proposed a number of protocols and schemes for this purpose. He et al. (INFOCOM 2007) have proposed a protocol—called CPDA—for carrying out additive data aggregation in a privacy-preserving manner for application in WSNs. The scheme has been quite popular and well-known.

Includes members:
  Member "reputation and trust based systems for wireless self organizing networks":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "homomorphic encryption theory and application")
  Member "a distributed protocol for detection of packet dropping attack in mobile ad hoc networks":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "homomorphic encryption theory and application")
  Member "a robust and secure aggregation protocol for wireless sensor networks":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "homomorphic encryption theory and application")
  Member "a trust based detection algorithm of selfish packet dropping nodes in a peer to peer wireless mesh network":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "secure and privacy preserving data aggregation protocols for wireless sensor networks")
  Member "a survey on wireless sensor network security":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "securing cluster heads in wireless sensor networks by a hybrid intrusion detection system based on data mining")
  Member "a distributed trust and reputation framework for mobile ad hoc networks":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "homomorphic encryption theory and application")

Question: Please tell me which class the source paper 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)