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: "be selfish and avoid dilemmas fork after withholding faw attacks on bitcoin"
  Abstract: In the Bitcoin system, participants are rewarded for solving cryptographic puzzles. In order to receive more consistent rewards over time, some participants organize mining pools and split the rewards from the pool in proportion to each participant's contribution. However, several attacks threaten the ability to participate in pools. The block withholding (BWH) attack makes the pool reward system unfair by letting malicious participants receive unearned wages while only pretending to contribute work. When two pools launch BWH attacks against each other, they encounter the miner's dilemma: in a Nash equilibrium, the revenue of both pools is diminished. In another attack called selfish mining, an attacker can unfairly earn extra rewards by deliberately generating forks.   In this paper, we propose a novel attack called a fork after withholding (FAW) attack. FAW is not just another attack. The reward for an FAW attacker is always equal to or greater than that for a BWH attacker, and it is usable up to four times more often per pool than in BWH attack. When considering multiple pools --- the current state of the Bitcoin network -- the extra reward for an FAW attack is about 56% more than that for a BWH attack. Furthermore, when two pools execute FAW attacks on each other, the miner's dilemma may not hold: under certain circumstances, the larger pool can consistently win. More importantly, an FAW attack, while using intentional forks, does not suffer from practicality issues, unlike selfish mining. We also discuss partial countermeasures against the FAW attack, but finding a cheap and efficient countermeasure remains an open problem. As a result, we expect to see FAW attacks among mining pools.

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 "bdos blockchain denial of service"):
  with members:
    - "competing semi selfish miners in bitcoin"
    - "bitcoin vs bitcoin cash coexistence or downfall of bitcoin cash"
    - "sok transparent dishonesty front running attacks on blockchain"
    - "selfish mining in ethereum"
    - "just enough security reducing proof of work ecological footprint"
    - "mind the mining"
    - "cryptocurrency egalitarianism a quantitative approach"
    - "flash boys 2 0 frontrunning transaction reordering and consensus instability in decentralized exchanges"

Connected through hyperedge HE-3 (induced by source paper "heb hybrid expenditure blockchain"):
  with members:
    - "mind the mining"
    - "squirrl automating attack discovery on blockchain incentive mechanisms with deep reinforcement learning"
    - "an axiomatic approach to block rewards"
    - "sbft a scalable and decentralized trust infrastructure"
    - "sbft a scalable decentralized trust infrastructure for blockchains"
    - "a survey on security and privacy issues of bitcoin"
    - "the gap game"
    - "bitcoin a natural oligopoly"

Connected through hyperedge HE-4 (induced by source paper "zero knowledge proof of identity sybil resistant anonymous authentication on permissionless blockchains and incentive compatible strictly dominant cryptocurrencies"):
  with members:
    - "diversification across mining pools optimal mining strategies under pow"
    - "sok tools for game theoretic models of security for cryptocurrencies"
    - "impossibility of full decentralization in permissionless blockchains"
    - "dfinity technology overview series consensus system"
    - "a game theoretic analysis of shard based permissionless blockchains"
    - "coconut threshold issuance selective disclosure credentials with applications to distributed ledgers"
    - "enhancing bitcoin security and performance with strong consistency via collective signing"
    - "keeping authorities honest or bust with decentralized witness cosigning"

Connected through hyperedge HE-5 (induced by source paper "competing semi selfish miners in bitcoin"):
  with members:
    - "blockchain mining games with pay forward"
    - "a deep dive into blockchain selfish mining"
    - "blockchain mining games"
    - "optimal selfish mining strategies in bitcoin"
    - "bitcoin ng a scalable blockchain protocol"
    - "on subversive miner strategies and block withholding attack in bitcoin digital currency"
    - "the miner s dilemma"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-6 (induced by source paper "impossibility of full decentralization in permissionless blockchains"):
  with members:
    - "bitcoin vs bitcoin cash coexistence or downfall of bitcoin cash"
    - "is stellar as secure as you think"
    - "decentralization in bitcoin and ethereum networks"
    - "reward sharing schemes for stake pools"
    - "the gap game"
    - "hijacking bitcoin routing attacks on cryptocurrencies"
    - "the miner s dilemma"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-7 (induced by source paper "an eye for an eye economics of retaliation in mining pools"):
  with members:
    - "bitcoin vs bitcoin cash coexistence or downfall of bitcoin cash"
    - "the gap game"
    - "optimal selfish mining strategies in bitcoin"
    - "on subversive miner strategies and block withholding attack in bitcoin digital currency"
    - "the miner s dilemma"
    - "majority is not enough bitcoin mining is vulnerable"
    - "analysis of bitcoin pooled mining reward systems"

Connected through hyperedge HE-8 (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"
    - "privacy preserving and efficient aggregation based on blockchain for power grid communications in smart communities"
    - "mof bc a memory optimized and flexible blockchain for large scale networks"
    - "blockchain a distributed solution to automotive security and privacy"
    - "majority is not enough bitcoin mining is vulnerable"

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)