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: "service oriented sharding with aspen"
  Abstract: The rise of blockchain-based cryptocurrencies has led to an explosion of services using distributed ledgers as their underlying infrastructure. However, due to inherently single-service oriented blockchain protocols, such services can bloat the existing ledgers, fail to provide sufficient security, or completely forego the property of trustless auditability. Security concerns, trust restrictions, and scalability limits regarding the resource requirements of users hamper the sustainable development of loosely-coupled services on blockchains. #R##N#This paper introduces Aspen, a sharded blockchain protocol designed to securely scale with increasing number of services. Aspen shares the same trust model as Bitcoin in a peer-to-peer network that is prone to extreme churn containing Byzantine participants. It enables introduction of new services without compromising the security, leveraging the trust assumptions, or flooding users with irrelevant messages.

Connected through hyperedge HE-1 (induced by source paper "hushrelay a privacy preserving efficient and scalable routing algorithm for off chain payments"):
  with members:
    - "concurrency and privacy with payment channel networks"
    - "topological analysis of bitcoin s lightning network"
    - "ant routing algorithm for the lightning network"
    - "routing cryptocurrency with the spider network"
    - "consensus in the age of blockchains"
    - "towards a concurrent and distributed route selection for payment channel networks"
    - "casper the friendly finality gadget"
    - "settling payments fast and private efficient decentralized routing for path based transactions"

Connected through hyperedge HE-2 (induced by source paper "ostraka secure blockchain scaling by node sharding"):
  with members:
    - "decentralization in bitcoin and ethereum networks"
    - "hotstuff bft consensus in the lens of blockchain"
    - "split scale scaling bitcoin by partitioning the utxo space"
    - "dietcoin shortcutting the bitcoin verification process for your smartphone"
    - "chainspace a sharded smart contracts platform"
    - "adding concurrency to smart contracts"
    - "casper the friendly finality gadget"
    - "enhancing bitcoin security and performance with strong consistency via collective signing"

Connected through hyperedge HE-3 (induced by source paper "polyshard coded sharding achieves linearly scaling efficiency and security simultaneously"):
  with members:
    - "speeding up distributed machine learning using codes"
    - "a game theoretic analysis of shard based permissionless blockchains"
    - "a scale out blockchain for value transfer with spontaneous sharding"
    - "blockclique scaling blockchains through transaction sharding in a multithreaded block graph"
    - "lagrange coded computing optimal design for resiliency security and privacy"
    - "polynomial codes an optimal design for high dimensional coded matrix multiplication"
    - "chainspace a sharded smart contracts platform"
    - "short dot computing large linear transforms distributedly using coded short dot products"

Connected through hyperedge HE-4 (induced by source paper "consensus in the age of blockchains"):
  with members:
    - "implicit consensus blockchain with unbounded throughput"
    - "blockchains consensus protocols in the wild"
    - "chainspace a sharded smart contracts platform"
    - "practical synchronous byzantine consensus"
    - "blockbench a framework for analyzing private blockchains"
    - "interactive proof of stake"
    - "enhancing bitcoin security and performance with strong consistency via collective signing"
    - "non determinism in byzantine fault tolerant replication"

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)