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: "blockchain enabled data marketplace design and challenges"
  Abstract: Data is of unprecedented importance today. The most valuable companies of today treat data as a commodity, which they trade and earn revenues. To facilitate such trading, data marketplaces have emerged. Present data marketplaces are inadequate as they fail to satisfy all the desirable properties - fairness, efficiency, security, privacy and adherence to regulations. In this article, we propose a blockchain enabled data marketplace solution that fulfills all required properties. We outline the design, show how to design such a system and discuss the challenges in building a complete data marketplace.

Connected through hyperedge HE-1 (induced by source paper "energy aware demand selection and allocation for real time iot data trading"):
  with members:
    - "towards secure and decentralized sharing of iot data"
    - "a conceptual marketplace model for iot generated personal data"
    - "enforcing private data usage control with blockchain and attested off chain contract execution"
    - "a decentralized iot data marketplace"
    - "idmob iot data marketplace on blockchain"
    - "mind my value a decentralized infrastructure for fair and trusted iot data trading"
    - "distributed approximation algorithms for the multiple knapsack problem"
    - "allocation of heterogeneous resources of an iot device to flexible services"

Connected through hyperedge HE-2 (induced by source paper "adversarial contract design for private data commercialization"):
  with members:
    - "implementation of smart contracts using hybrid architectures with on and off blockchain components"
    - "contract design for energy demand response"
    - "market model and optimal pricing scheme of big data and internet of things iot"
    - "buying private data without verification"
    - "adaptive contract design for crowdsourcing markets bandit algorithms for repeated principal agent problems"
    - "differential privacy an economic method for choosing epsilon"
    - "a theory of pricing private data"
    - "privacy aware mechanism design"

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)