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: "requirements for ethereum private sidechains"
  Abstract: The Enterprise Ethereum Client Specification by the Enterprise Ethereum Alliance defines the requirements which Ethereum Clients offering private smart contract capabilities should comply with. This specification though ground breaking, misses some important blockchain requirements and does not fully consider the requirements of Ethereum Clients offering Private Sidechain capabilities. This paper presents the case for Private Sidechains and defines requirements to be complied with to deliver this technology. #R##N#The capabilities of three blockchain clients have been analysed based on the requirements: Quorum, Parity, and Hyperledger Fabric. Quorum and Hyperledger Fabric operate as private consortium blockchains where as Parity delivers private transaction capabilities on top of Ethereum MainNet. These differing approaches has led to different strengths and weaknesses which has resulted in each client not complying with one or more key requirement. In particular, none of the reviewed blockchain clients support the ability to determine bootstrap information to establish on-demand blockchains and none of the clients support secure management and pinning from Ethereum MainNet. #R##N#This paper presents Ethereum Private Sidechains and a range of technologies which allow it to deliver on complex sidechain requirements. Ethereum Registration Authorities are presented, which allow entities which have not previously interacted to securely obtain information to bootstrap a sidechain, and a Management and Pinning strategy is described which allows the state of a sidechain to be securely pinned to Ethereum MainNet without compromising privacy.

Connected through hyperedge HE-1 (induced by source paper "atomic crosschain transactions white paper"):
  with members:
    - "atomic crosschain transactions for ethereum private sidechains"

Connected through hyperedge HE-2 (induced by source paper "the merits of using ethereum mainnet as a coordination blockchain for ethereum private sidechains"):
  with members:
    - "atomic crosschain transactions for ethereum private sidechains"
    - "selfish mining in ethereum"
    - "anonymous state pinning for private blockchains"
    - "decentralization in bitcoin and ethereum networks"
    - "assessing security and performances of consensus algorithms for permissioned blockchains"
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "on the longest chain rule and programmed self destruction of crypto currencies"

Connected through hyperedge HE-3 (induced by source paper "atomic crosschain transactions for ethereum private sidechains"):
  with members:
    - "sidechains and interoperability"
    - "anonymous state pinning for private blockchains"
    - "correctness analysis of ibft"
    - "hyperledger fabric a distributed operating system for permissioned blockchains"

Connected through hyperedge HE-4 (induced by source paper "sidechains and interoperability"):
  with members:
    - "anonymous state pinning for private blockchains"
    - "casper the friendly finality gadget"

Connected through hyperedge HE-5 (induced by source paper "anonymous state pinning for private blockchains"):
  with members:
    - "hyperledger fabric a distributed operating system for permissioned blockchains"

Connected through hyperedge HE-6 (induced by source paper "application level authentication for ethereum private blockchain atomic crosschain transactions"):
  with members:
    - "atomic crosschain transactions for ethereum private sidechains"

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)