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: "smart contract based access control for the internet of things"
  Abstract: This paper investigates a critical access control issue in the Internet of Things (IoT). In particular, we propose a smart contract-based framework, which consists of multiple access control contracts (ACCs), one judge contract (JC) and one register contract (RC), to achieve distributed and trustworthy access control for IoT systems. Each ACC provides one access control method for a subject-object pair, and implements both static access right validation based on predefined policies and dynamic access right validation by checking the behavior of the subject. The JC implements a misbehavior-judging method to facilitate the dynamic validation of the ACCs by receiving misbehavior reports from the ACCs, judging the misbehavior and returning the corresponding penalty. The RC registers the information of the access control and misbehavior-judging methods as well as their smart contracts, and also provides functions (e.g., register, update and delete) to manage these methods. To demonstrate the application of the framework, we provide a case study in an IoT system with one desktop computer, one laptop and two Raspberry Pi single-board computers, where the ACCs, JC and RC are implemented based on the Ethereum smart contract platform to achieve the access control.

Connected through hyperedge HE-1 (induced by source paper "scaling blockchains to support electronic health records for hospital systems"):
  with members:
    - "bpds a blockchain based privacy preserving data sharing for electronic medical records"
    - "analysis of hashrate based double spending"

Connected through hyperedge HE-2 (induced by source paper "oauth 2 0 authorization using blockchain based tokens"):
  with members:
    - "interacting with the internet of things using smart contracts and blockchain technologies"
    - "oauth 2 0 meets blockchain for authorization in constrained iot environments"

Connected through hyperedge HE-3 (induced by source paper "blockchain for 5g and beyond networks a state of the art survey"):
  with members:
    - "ekiden a platform for confidentiality preserving trustworthy and performant smart contracts"
    - "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"

Connected through hyperedge HE-4 (induced by source paper "blockchain for the internet of things present and future"):
  with members:
    - "machine learning for wireless communications in the internet of things a comprehensive survey"
    - "block4forensic an integrated lightweight blockchain framework for forensics applications of connected vehicles"
    - "securing the internet of things in the age of machine learning and software defined networking"
    - "quality of information in mobile crowdsensing survey and research challenges"
    - "lsb a lightweight scalable blockchain for iot security and privacy"
    - "learning to detect and mitigate cross layer attacks in wireless networks framework and applications"
    - "blockchain a distributed solution to automotive security and privacy"
    - "providing privacy safety and security in iot based transactive energy systems using distributed ledgers"

Connected through hyperedge HE-5 (induced by source paper "consentio managing consent to data access using permissioned blockchains"):
  with members:
    - "parblockchain leveraging transaction parallelism in permissioned blockchain systems"
    - "fastfabric scaling hyperledger fabric to 20 000 transactions per second"
    - "a blockchain based scheme for access control in e health scenarios"
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "performance benchmarking and optimizing hyperledger fabric blockchain platform"
    - "decentralized user centric access control using pubsub over blockchain"
    - "secure and trustable electronic medical records sharing using blockchain"

Connected through hyperedge HE-6 (induced by source paper "secure iot access at scale using blockchains and smart contracts"):
  with members:
    - "smart contracts for the internet of things opportunities and challenges"
    - "smart contracts for machine to machine communication possibilities and limitations"

Connected through hyperedge HE-7 (induced by source paper "interledger smart contracts for decentralized authorization to constrained things"):
  with members:
    - "interacting with the internet of things using smart contracts and blockchain technologies"
    - "blendcac a blockchain enabled decentralized capability based access control for iots"

Connected through hyperedge HE-8 (induced by source paper "oauth 2 0 meets blockchain for authorization in constrained iot environments"):
  with members:
    - "interacting with the internet of things using smart contracts and blockchain technologies"
    - "blendcac a blockchain enabled decentralized capability based access control for iots"

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)