human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge is induced by one source paper and its member nodes are the cited papers.

Details of the hypergraph:
Center hyperedge (induced by source paper "sok of used cryptography in blockchain"):
  Abstract: The underlying fundaments of blockchain are cryptography and cryptographic concepts that provide reliable and secure decentralized solutions. Although many recent papers study the use-cases of blockchain in different industrial areas, such as finance, health care, legal relations, IoT, information security, and consensus building systems, only few studies scrutinize the cryptographic concepts used in blockchain. To the best of our knowledge, there is no Systematization of Knowledge (SoK) that gives a complete picture of the existing cryptographic concepts which have been deployed or have the potential to be deployed in blockchain. In this paper, we thoroughly review and systematize all cryptographic concepts which are already used in blockchain. Additionally, we give a list of cryptographic concepts which have not yet been applied but have big potentials to improve the current blockchain solutions. We also include possible instantiations of these cryptographic concepts in the blockchain domain. Last but not least, we explicitly postulate 21 challenging problems that cryptographers interested in blockchain can work on.

Includes members:
  Member "sef a secure fountain architecture for slashing storage costs in blockchains":
    also connected through other hyperedges:
      (none)
  Member "dfinity technology overview series consensus system":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "surface a practical blockchain consensus algorithm for real world networks")
  Member "celer network bring internet scale to every blockchain":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "privacy utility tradeoffs in routing cryptocurrency over payment channel networks")
  Member "raziel private and verifiable smart contracts on blockchains":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "deductive proof of ethereum smart contracts using why3")
  Member "blendcac a blockchain enabled decentralized capability based access control for iots":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "microchain a light hierarchical consensus protocol for iot system")
  Member "hyperledger fabric a distributed operating system for permissioned blockchains":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "tenderbake classical bft style consensus for public blockchains")
  Member "a survey on security and privacy issues of bitcoin":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "on the feasibility of sybil attacks in shard based permissionless blockchains")
  Member "privacy preserving and efficient aggregation based on blockchain for power grid communications in smart communities":
    also connected through other hyperedges:
      - Hyperedge HE-7 (induced by source paper "blockchain for 5g and beyond networks a state of the art survey")

Question: Please tell me which class the source paper 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)