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: "solida a blockchain protocol based on reconfigurable byzantine consensus"
  Abstract: The decentralized cryptocurrency Bitcoin has experienced great success but also encountered many challenges. One of the challenges has been the long confirmation time. Another challenge is the lack of incentives at certain steps of the protocol, raising concerns for transaction withholding, selfish mining, etc. To address these challenges, we propose Solida, a decentralized blockchain protocol based on reconfigurable Byzantine consensus augmented by proof-of-work. Solida improves on Bitcoin in confirmation time, and provides safety and liveness assuming the adversary control less than (roughly) one-third of the total mining power.

Connected through hyperedge HE-1 (induced by source paper "on the feasibility of sybil attacks in shard based permissionless blockchains"):
  with members:
    - "polyshard coded sharding achieves linearly scaling efficiency and security simultaneously"
    - "chain of trust can trusted hardware help scaling blockchains"
    - "towards scaling blockchain systems via sharding"
    - "a survey on security and privacy issues of bitcoin"
    - "lagrange coded computing optimal design for resiliency security and privacy"
    - "blockchain mining games"
    - "enhancing bitcoin security and performance with strong consistency via collective signing"
    - "centrally banked cryptocurrencies"

Connected through hyperedge HE-2 (induced by source paper "incentive analysis of bitcoin ng revisited"):
  with members:
    - "analysis of nakamoto consensus revisited"
    - "scaling nakamoto consensus to thousands of transactions per second"
    - "ohie blockchain scaling made simple"
    - "the gap game"
    - "enhancing bitcoin security and performance with strong consistency via collective signing"
    - "optimal selfish mining strategies in bitcoin"
    - "bitcoin ng a scalable blockchain protocol"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-3 (induced by source paper "a survey on consensus mechanisms and mining strategy management in blockchain networks"):
  with members:
    - "decentralization in bitcoin and ethereum networks"
    - "information and communications technologies for sustainable development goals state of the art needs and perspectives"
    - "a scale out blockchain for value transfer with spontaneous sharding"
    - "a survey on security and privacy issues of bitcoin"
    - "on cyber risk management of blockchain networks a game theoretic approach"
    - "scaling nakamoto consensus to thousands of transactions per second"
    - "competitive data trading in wireless powered internet of things iot crowdsensing systems with blockchain"
    - "blockchained on device federated learning"

Connected through hyperedge HE-4 (induced by source paper "deconstructing blockchains a comprehensive survey on consensus membership and structure"):
  with members:
    - "dfinity technology overview series consensus system"
    - "analysis of the xrp ledger consensus protocol"
    - "hotstuff bft consensus in the lens of blockchain"
    - "evaluating the red belly blockchain"
    - "an empirical analysis of anonymity in zcash"
    - "a survey on security and privacy issues of bitcoin"
    - "blockchains consensus protocols in the wild"
    - "cachezoom how sgx amplifies the power of cache attacks"

Connected through hyperedge HE-5 (induced by source paper "sok blockchain technology and its potential use cases"):
  with members:
    - "decentralization in bitcoin and ethereum networks"
    - "hunting the ethereum smart contract color inspired inspection of potential attacks"
    - "a survey on security and privacy issues of bitcoin"
    - "a new look at the refund mechanism in the bitcoin payment protocol"
    - "consensus in the age of blockchains"
    - "when the cookie meets the blockchain privacy risks of web payments via cryptocurrencies"
    - "bitcoin ng a scalable blockchain protocol"
    - "a first look at the usability of bitcoin key management"

Connected through hyperedge HE-6 (induced by source paper "the consensus number of a cryptocurrency"):
  with members:
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "blockchains consensus protocols in the wild"
    - "a byzantine fault tolerant ordering service for the hyperledger fabric blockchain platform"
    - "revisiting fast practical byzantine fault tolerance"
    - "enhancing bitcoin security and performance with strong consistency via collective signing"
    - "bitcoin meets strong consistency"
    - "cryptocurrencies without proof of work"

Connected through hyperedge HE-7 (induced by source paper "sef a secure fountain architecture for slashing storage costs in blockchains"):
  with members:
    - "polyshard coded sharding achieves linearly scaling efficiency and security simultaneously"
    - "erasure code based low storage blockchain node"
    - "consensus in the age of blockchains"
    - "dynamic distributed storage for scaling blockchains"
    - "a survey on network codes for distributed storage"
    - "efficient erasure decoding of reed solomon codes"

Connected through hyperedge HE-8 (induced by source paper "blockguard adaptive blockchain security"):
  with members:
    - "atomic cross chain swaps"
    - "adding concurrency to smart contracts"
    - "enhancing bitcoin security and performance with strong consistency via collective signing"
    - "bitcoin ng a scalable blockchain protocol"
    - "centrally banked cryptocurrencies"
    - "bitcoin meets strong consistency"

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)