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: "ekiden a platform for confidentiality preserving trustworthy and performant smart contracts"
  Abstract: Smart contracts are applications that execute on blockchains. Today they manage billions of dollars in value and motivate visionary plans for pervasive blockchain deployment. While smart contracts inherit the availability and other security assurances of blockchains, however, they are impeded by blockchains' lack of confidentiality and poor performance. We present Ekiden, a system that addresses these critical gaps by combining blockchains with Trusted Execution Environments (TEEs). Ekiden leverages a novel architecture that separates consensus from execution, enabling efficient TEE-backed confidentiality-preserving smart-contracts and high scalability. Our prototype (with Tendermint as the consensus layer) achieves example performance of 600x more throughput and 400x less latency at 1000x less cost than the Ethereum mainnet. Another contribution of this paper is that we systematically identify and treat the pitfalls arising from harmonizing TEEs and blockchains. Treated separately, both TEEs and blockchains provide powerful guarantees, but hybridized, though, they engender new attacks. For example, in naive designs, privacy in TEE-backed contracts can be jeopardized by forgery of blocks, a seemingly unrelated attack vector. We believe the insights learned from Ekiden will prove to be of broad importance in hybridized TEE-blockchain systems.

Connected through hyperedge HE-1 (induced by source paper "on the convergence of artificial intelligence and distributed ledger technology a scoping review and future research agenda"):
  with members:
    - "energy recycling blockchain with proof of deep learning"
    - "decentralized and collaborative ai on blockchain"
    - "sok transparent dishonesty front running attacks on blockchain"
    - "reliable federated learning for mobile networks"
    - "keystone an open framework for architecting tees"
    - "tensorscone a secure tensorflow framework using intel sgx"
    - "coin ai a proof of useful work scheme for blockchain based distributed deep learning"
    - "mobile edge computing blockchain and reputation based crowdsourcing iot federated learning a secure decentralized and privacy preserving system"

Connected through hyperedge HE-2 (induced by source paper "formalising and verifying smart contracts with solidifier a bounded model checker for solidity"):
  with members:
    - "smt friendly formalization of the solidity memory model"
    - "solc verify a modular verifier for solidity smart contracts"
    - "a semantic framework for the security analysis of ethereum smart contracts"
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "formal specification and verification of smart contracts for azure blockchain"
    - "securify practical security analysis of smart contracts"

Connected through hyperedge HE-3 (induced by source paper "the security reference architecture for blockchains towards a standardized model for studying vulnerabilities threats and defenses"):
  with members:
    - "a survey on ethereum systems security vulnerabilities attacks and defenses"
    - "security and privacy on blockchain"
    - "deconstructing blockchains a comprehensive survey on consensus membership and structure"
    - "truffle tests for free replaying ethereum smart contracts for transparency"
    - "blockchain technologies for the internet of things research issues and challenges"
    - "exploring the attack surface of blockchain a systematic overview"
    - "strongchain transparent and collaborative proof of work consensus"
    - "a survey on consensus mechanisms and mining strategy management in blockchain networks"

Connected through hyperedge HE-4 (induced by source paper "blockchain for 5g and beyond networks a state of the art survey"):
  with members:
    - "a key 6g challenge and opportunity connecting the remaining 4 billions a survey on rural connectivity"
    - "on safeguarding privacy and security in the framework of federated learning"
    - "a survey on consensus mechanisms and mining strategy management in blockchain networks"
    - "trustsas a trustworthy spectrum access system for the 3 5 ghz cbrs band"
    - "blockchain enabled authentication handover with efficient privacy protection in sdn based 5g networks"
    - "6g wireless communication systems applications requirements technologies challenges and research directions"
    - "a vision of 6g wireless systems applications trends technologies and open research problems"
    - "federated learning challenges methods and future directions"

Connected through hyperedge HE-5 (induced by source paper "a security reference architecture for blockchains"):
  with members:
    - "strongchain transparent and collaborative proof of work consensus"
    - "insight into insiders and it a survey of insider threat taxonomies analysis modeling and countermeasures"
    - "dfinity technology overview series consensus system"
    - "short paper towards more reliable bitcoin timestamps"
    - "the latest gossip on bft consensus"
    - "finding the greedy prodigal and suicidal contracts at scale"
    - "sabre protecting bitcoin against routing attacks"
    - "scilla a smart contract intermediate level language"

Connected through hyperedge HE-6 (induced by source paper "integration of blockchain and cloud of things architecture applications and challenges"):
  with members:
    - "blockchain technologies for the internet of things research issues and challenges"
    - "a survey on consensus mechanisms and mining strategy management in blockchain networks"
    - "designing a blockchain based iot with ethereum swarm and lora the software solution to create high availability with minimal security risks"
    - "energy crowdsourcing and peer to peer energy trading in blockchain enabled smart grids"
    - "bpds a blockchain based privacy preserving data sharing for electronic medical records"
    - "a survey on the security of blockchain systems"
    - "wip a novel blockchain based trust model for cloud identity management"
    - "blockchain based smart contracts applications and challenges"

Connected through hyperedge HE-7 (induced by source paper "hyperservice interoperability and programmability across heterogeneous blockchains"):
  with members:
    - "concurrency and privacy with payment channel networks"
    - "keystone an open framework for architecting tees"
    - "atomic cross chain swaps"
    - "saql a stream based query system for real time abnormal system behavior detection"
    - "aiql enabling efficient attack investigation from system monitoring data"
    - "chainspace a sharded smart contracts platform"
    - "a concurrent perspective on smart contracts"
    - "enhancing bitcoin security and performance with strong consistency via collective signing"

Connected through hyperedge HE-8 (induced by source paper "keystone an open framework for architecting tees"):
  with members:
    - "zombieload cross privilege boundary data sampling"
    - "practical verifiable in network filtering for ddos defense"
    - "sanctorum a lightweight security monitor for secure enclaves"
    - "spectre attacks exploiting speculative execution"
    - "besfs mechanized proof of an iago safe filesystem for enclaves"
    - "privado practical and secure dnn inference"
    - "mi6 secure enclaves in a speculative out of order processor"
    - "teechan payment channels using trusted execution environments"

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)