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: "teechain a secure asynchronous blockchain payment network"
  Abstract: Blockchain protocols exchange payment transactions securely, but their performance is limited by the need to achieve global consensus. Payment networks, as a second layer on top of blockchains, allow more efficient payments between parties. Existing payment networks, however, are fundamentally insecure: they assume synchronous blockchain access, i.e., that participants can write transactions to the blockchain within bounded time. As shown recently, attackers can delay transactions with current blockchains, which only offer best-effort write latencies, and thus steal funds. #R##N#We describe Teechain, the first layer-two payment network that only requires asynchronous blockchain access. Teechain exploits trusted execution environments (TEEs) in modern CPUs: Teechain constructs a decentralised network of TEEs and uses TEEs to secure collateral funds in payment channels without further interaction with the blockchain. Since TEEs provide no availability guarantees and may be compromised themselves, Teechain mitigates against Byzantine TEE failures through a novel combination of chain replication and threshold secret sharing. Teechain achieves at least 33x higher transaction throughput than the Lightning Network with similar latencies, while placing 75% fewer transactions on the blockchain in the common case. A Teechain deployment with 30 machines can handle over 1 million Bitcoin transactions per second.

Connected through hyperedge HE-1 (induced by source paper "fail safe watchtowers and short lived assertions for payment channels"):
  with members:
    - "concurrency and privacy with payment channel networks"
    - "towards secure and efficient payment channels"
    - "bitcoin ng a scalable blockchain protocol"

Connected through hyperedge HE-2 (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-3 (induced by source paper "blockchain technologies for the internet of things research issues and challenges"):
  with members:
    - "a survey on the security of blockchain systems"
    - "a delay tolerant payment scheme based on the ethereum blockchain"
    - "towards trusted social networks with blockchain technology"
    - "a survey on security and privacy issues of bitcoin"
    - "an empirical analysis of linkability in the monero blockchain"
    - "blockchain a distributed solution to automotive security and privacy"
    - "from pretty good to great enhancing pgp using bitcoin and the blockchain"
    - "ipfs content addressed versioned p2p file system"

Connected through hyperedge HE-4 (induced by source paper "truxen a trusted computing enhanced blockchain"):
  with members:
    - "ekiden a platform for confidentiality preserving trustworthy and performant smart contracts"
    - "blockchain and trusted computing problems pitfalls and a solution for hyperledger fabric"
    - "blockchains consensus protocols in the wild"
    - "decentralized prediction market without arbiters"
    - "untangling blockchain a data processing view of blockchain systems"
    - "proof of luck an efficient blockchain consensus protocol"
    - "bitcoin ng a scalable blockchain protocol"
    - "a review of techniques to mitigate sybil attacks"

Connected through hyperedge HE-5 (induced by source paper "blockchain and trusted computing problems pitfalls and a solution for hyperledger fabric"):
  with members:
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "blockchains consensus protocols in the wild"
    - "software grand exposure sgx cache attacks are practical"
    - "rollback and forking detection for trusted execution environments using lightweight collective memory"
    - "malware guard extension using sgx to conceal cache attacks"
    - "hijacking bitcoin routing attacks on cryptocurrencies"

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)