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: "new kids on the block an analysis of modern blockchains"
  Abstract: Half a decade after Bitcoin became the first widely used cryptocurrency, blockchains are receiving considerable interest from industry and the research community. Modern blockchains feature services such as name registration and smart contracts. Some employ new forms of consensus, such as proof-of-stake instead of proof-of-work. However, these blockchains are so far relatively poorly investigated, despite the fact that they move considerable assets. In this paper, we explore three representative, modern blockchains---Ethereum, Namecoin, and Peercoin. Our focus is on the features that set them apart from the pure currency use case of Bitcoin. We investigate the blockchains' activity in terms of transactions and usage patterns, identifying some curiosities in the process. For Ethereum, we are mostly interested in the smart contract functionality it offers. We also carry out a brief analysis of issues that are introduced by negligent design of smart contracts. In the case of Namecoin, our focus is how the name registration is used and has developed over time. For Peercoin, we are interested in the use of proof-of-stake, as this consensus algorithm is poorly understood yet used to move considerable value. Finally, we relate the above to the fundamental characteristics of the underlying peer-to-peer networks. We present a crawler for Ethereum and give statistics on the network size. For Peercoin and Namecoin, we identify the relatively small size of the networks and the weak bootstrapping process.

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 "empirically analyzing ethereum s gas mechanism"):
  with members:
    - "an empirical study of speculative concurrency in ethereum smart contracts"
    - "decentralization in bitcoin and ethereum networks"
    - "an efficient framework for optimistic concurrent execution of smart contracts"
    - "chainspace a sharded smart contracts platform"
    - "adding concurrency to smart contracts"
    - "an empirical analysis of smart contracts platforms applications and design patterns"
    - "optimal selfish mining strategies in bitcoin"
    - "bitcoin transaction graph analysis"

Connected through hyperedge HE-3 (induced by source paper "truffle tests for free replaying ethereum smart contracts for transparency"):
  with members:
    - "probabilistic smart contracts secure randomness on the blockchain"
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "detecting token systems on ethereum"
    - "contractfuzzer fuzzing smart contracts for vulnerability detection"
    - "rethinking blockchain security position paper"
    - "securify practical security analysis of smart contracts"

Connected through hyperedge HE-4 (induced by source paper "ubaas a unified blockchain as a service platform"):
  with members:
    - "a survey on the security of blockchain systems"

Connected through hyperedge HE-5 (induced by source paper "fission a provably fast scalable and secure permissionless blockchain"):
  with members:
    - "scaling nakamoto consensus to thousands of transactions per second"
    - "casper the friendly finality gadget"
    - "ipfs content addressed versioned p2p file system"
    - "majority is not enough bitcoin mining is vulnerable"
    - "distributed selfish load balancing"

Connected through hyperedge HE-6 (induced by source paper "compounding of wealth in proof of stake cryptocurrencies"):
  with members:
    - "reward sharing schemes for stake pools"
    - "casper the friendly finality gadget"
    - "optimal selfish mining strategies in bitcoin"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-7 (induced by source paper "social signals in the ethereum trading network"):
  with members:
    - "an empirical analysis of smart contracts platforms applications and design patterns"

Connected through hyperedge HE-8 (induced by source paper "an empirical analysis of smart contracts platforms applications and design patterns"):
  with members:
    - "dissecting ponzi schemes on ethereum identification analysis and impact"
    - "an analysis of bitcoin op_return metadata"
    - "smart contract templates foundations design landscape and research directions"
    - "note on fair coin toss via bitcoin"

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)