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: "privacy preserving and efficient aggregation based on blockchain for power grid communications in smart communities"
  Abstract: Intelligence is one of the most important aspects in the development of our future communities. Ranging from smart home, smart building, to smart city, all these smart infrastructures must be supported by intelligent power supply. Smart grid is proposed to solve all challenges of future electricity supply. In smart grid, in order to realize optimal scheduling, a Smart Meter (SM) is installed at each home to collect the near real-time electricity consumption data, which can be used by the utilities to offer better smart home services. However, the near real-time data may disclose user's privacy. An adversary may track the application usage patterns by analyzing the user's electricity consumption profile. In this paper, we propose a privacy-preserving and efficient data aggregation scheme. We divide users into different groups and each group has a private blockchain to record its members' data. To preserve the inner privacy within a group, we use pseudonym to hide user's identity, and each user may create multiple pseudonyms and associate his/her data with different pseudonyms. In addition, the bloom filter is adopted for fast authentication. The analysis shows that the proposed scheme can meet the security requirements, and achieve a better performance than other popular methods.

Connected through hyperedge HE-1 (induced by source paper "blockchain for 5g and beyond networks a state of the art survey"):
  with members:
    - "ekiden a platform for confidentiality preserving trustworthy and performant smart contracts"
    - "a key 6g challenge and opportunity connecting the remaining 4 billions a survey on rural connectivity"
    - "on safeguarding privacy and security in the framework of federated learning"
    - "a survey on consensus mechanisms and mining strategy management in blockchain networks"
    - "trustsas a trustworthy spectrum access system for the 3 5 ghz cbrs band"
    - "blockchain enabled authentication handover with efficient privacy protection in sdn based 5g networks"
    - "6g wireless communication systems applications requirements technologies challenges and research directions"
    - "a vision of 6g wireless systems applications trends technologies and open research problems"

Connected through hyperedge HE-2 (induced by source paper "sok of used cryptography in blockchain"):
  with members:
    - "sef a secure fountain architecture for slashing storage costs in blockchains"
    - "dfinity technology overview series consensus system"
    - "celer network bring internet scale to every blockchain"
    - "raziel private and verifiable smart contracts on blockchains"
    - "blendcac a blockchain enabled decentralized capability based access control for iots"
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "a survey on security and privacy issues of bitcoin"
    - "sharvot secret share based voting on the blockchain"

Connected through hyperedge HE-3 (induced by source paper "when energy trading meets blockchain in electrical power system the state of the art"):
  with members:
    - "blockchain technologies for the internet of things research issues and challenges"
    - "decentralized p2p energy trading under network constraints in a low voltage network"
    - "on the applicability of distributed ledger architectures to peer to peer energy trading framework"
    - "peer to peer and community based markets a comprehensive review"
    - "peer to peer energytrade a distributed private energy trading platform"
    - "secure and privacy friendly local electricity trading and billing in smart grid"
    - "peer to peer energy trading with sustainable user participation a game theoretic approach"
    - "auction mechanisms in cloud fog computing resource allocation for public blockchain networks"

Connected through hyperedge HE-4 (induced by source paper "impact of consensus on appendable block blockchain for iot"):
  with members:
    - "the ico phenomenon and its relationships with ethereum smart contract environment"
    - "a survey on security and privacy issues of bitcoin"
    - "mof bc a memory optimized and flexible blockchain for large scale networks"
    - "blockchain a distributed solution to automotive security and privacy"
    - "be selfish and avoid dilemmas fork after withholding faw attacks on bitcoin"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-5 (induced by source paper "achieving data utility privacy tradeoff in internet of medical things a machine learning approach"):
  with members:
    - "achieving efficient and secure data acquisition for cloud supported internet of things in smart grid"
    - "differentially private k means clustering"
    - "composition attacks and auxiliary information in data privacy"

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)