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 "permissionless blockchains and secure logging"):
  Abstract: The blockchain technology enables mutually untrusting participants to reach consensus on the state of a distributed and decentralized ledger (called a blockchain) in a permissionless setting. The consensus protocol of the blockchain imposes a unified view of the system state over the global network, and once a block is stable in the blockchain, its data is visible to all users and cannot be retrospectively modified or removed. Due to these properties, the blockchain technology is regarded as a general consensus infrastructure and based on which a variety of systems have been built. This article presents a study and survey of permissionless blockchain systems in the context of secure logging. We postulate the most essential properties required by a secure logging system and by considering a wide range of applications, we give insights into how the blockchain technology matches these requirements. Based on the survey, we motivate related research perspectives and challenges for blockchain-based secure logging systems, and we highlight potential solutions to some specific problems.

Includes members:
  Member "short paper towards more reliable bitcoin timestamps":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "the security reference architecture for blockchains towards a standardized model for studying vulnerabilities threats and defenses")
  Member "blockchain based tls notary service":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "the security reference architecture for blockchains towards a standardized model for studying vulnerabilities threats and defenses")
  Member "pdfs practical data feed service for smart contracts":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "the security reference architecture for blockchains towards a standardized model for studying vulnerabilities threats and defenses")
  Member "scaling nakamoto consensus to thousands of transactions per second":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "surface a practical blockchain consensus algorithm for real world networks")
  Member "contour a practical system for binary transparency":
    also connected through other hyperedges:
      - Hyperedge HE-5 (induced by source paper "the security reference architecture for blockchains towards a standardized model for studying vulnerabilities threats and defenses")
  Member "efficient gossip protocols for verifying the consistency of certificate logs":
    also connected through other hyperedges:
      - Hyperedge HE-6 (induced by source paper "the era of tls 1 3 measuring deployment and use with active and passive methods")

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)