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: "zeroblock preventing selfish mining in bitcoin"
  Abstract: Bitcoin was recently introduced as a peer-to-peer electronic currency in order to facilitate transactions outside the traditional financial system. The core of Bitcoin, the Blockchain, is the history of the transactions in the system maintained by all nodes as a distributed shared register. New blocks in the Blockchain contain the last transactions in the system and are added by nodes (miners) after a block mining process that consists in solving a resource consuming proof-of-work (cryptographic puzzle). The reward is a motivation for mining process but also could be an incentive for attacks such as selfish mining. In this paper we propose a solution for one of the major problems in Bitcoin : selfish mining or block withholding attack. This attack is conducted by adversarial or selfish nodes in order to either earn undue rewards or waste the computational power of honest nodes. Contrary to recent solutions, our solution, ZeroBlock, prevents block withholding using a technique free of forgeable timestamps. Moreover, we show that our solution is also compliant with nodes churn.

Connected through hyperedge HE-1 (induced by source paper "exploring the attack surface of blockchain a systematic overview"):
  with members:
    - "scalable byzantine consensus via hardware assisted secret sharing"
    - "security services using blockchains a state of the art survey"
    - "a survey on the security of blockchain systems"
    - "an empirical analysis of anonymity in zcash"
    - "towards blockchain driven secure and transparent audit logs"
    - "end to end analysis of in browser cryptojacking"
    - "linbft linear communication byzantine fault tolerance for public blockchains"
    - "a survey on security and privacy issues of bitcoin"

Connected through hyperedge HE-2 (induced by source paper "mind the gap trade offs between distributed ledger technology characteristics"):
  with members:
    - "on the origins and variations of blockchain technologies"
    - "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"
    - "hijacking bitcoin routing attacks on cryptocurrencies"
    - "the blockchain anomaly"

Connected through hyperedge HE-3 (induced by source paper "selfish mining in ethereum"):
  with members:
    - "deconstructing the blockchain to approach physical limits"
    - "optimal selfish mining strategies in bitcoin"
    - "majority is not enough bitcoin mining is vulnerable"
    - "theoretical bitcoin attacks with less than half of the computational power draft"

Connected through hyperedge HE-4 (induced by source paper "countering selfish mining in blockchains"):
  with members:
    - "merging supply chain and blockchain technologies"
    - "be selfish and avoid dilemmas fork after withholding faw attacks on bitcoin"
    - "centrally banked cryptocurrencies"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-5 (induced by source paper "block arrivals in the bitcoin blockchain"):
  with members:
    - "analysis of hashrate based double spending"
    - "majority is not enough bitcoin mining is vulnerable"
    - "analysis of bitcoin pooled mining reward systems"

Connected through hyperedge HE-6 (induced by source paper "rdv an alternative to proof of work and a real decentralized consensus for blockchain"):
  with members:
    - "a survey on the security of blockchain systems"
    - "security of electronic payment systems a comprehensive survey"
    - "the miner s dilemma"
    - "majority is not enough bitcoin mining is vulnerable"
    - "theoretical bitcoin attacks with less than half of the computational power draft"
    - "on bitcoin and red balloons"
    - "randomized protocols for asynchronous consensus"

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)