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: "on the origins and variations of blockchain technologies"
  Abstract: We explore the origins of blockchain technologies to better understand the enduring needs they address. We identify the five key elements of a blockchain, show embodiments of these elements, and examine how these elements come together to yield important properties in selected systems. To facilitate comparing the many variations of blockchains, we also describe the four crucial roles of blockchain participants common to all blockchains. Our historical exploration highlights the 1979 work of David Chaum whose vault system embodies many of the elements of blockchains.

Connected through hyperedge HE-1 (induced by source paper "mind the gap trade offs between distributed ledger technology characteristics"):
  with members:
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "a survey on the security of blockchain systems"
    - "a blockchain based approach for data accountability and provenance tracking"
    - "blockbench a framework for analyzing private blockchains"
    - "untangling blockchain a data processing view of blockchain systems"
    - "zeroblock preventing selfish mining in bitcoin"
    - "hijacking bitcoin routing attacks on cryptocurrencies"
    - "the blockchain anomaly"

Connected through hyperedge HE-2 (induced by source paper "exploring the added value of blockchain technology for the healthcare domain"):
  with members:
    - "conceptualizing blockchains characteristics applications"
    - "applications of blockchain technology beyond cryptocurrency"
    - "secure and trustable electronic medical records sharing using blockchain"

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)