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: "rollerchain a blockchain with safely pruneable full blocks"
  Abstract: Bitcoin is the first successful decentralized global digital cash system. Its mining process requires intense computational resources, therefore its usefulness remains a disputable topic. We aim to solve three problems with Bitcoin and other blockchain systems of today by repurposing their work. First, space to store a blockchain is growing linearly with number of transactions. Second, a honest node is forced to be irrational regarding storing full blocks by a way implementations are done. Third, a trustless bootstrapping process for a new node involves downloading and processing all the transactions ever written into a blockchain. #R##N#In this paper we present a new consensus protocol for Bitcoin-like peer-to-peer systems where a right to generate a block is given to a party providing non-interactive proofs of storing a subset of the past state snapshots. Unlike the blockchain systems in use today, a network using our protocol is safe if the nodes prune full blocks not needed for mining. #R##N#We extend the GKL model to describe our Proof-of-Work scheme and a transactional model modifications needed for it. We provide a detailed analysis of our protocol and proofs of its security.

Connected through hyperedge HE-1 (induced by source paper "lightchain a dht based blockchain for resource constrained environments"):
  with members:
    - "interlaced fully decentralized churn stabilization for skip graph based dhts"
    - "hyperledger fabric a distributed operating system for permissioned blockchains"
    - "casper the friendly finality gadget"
    - "bitcoin ng a scalable blockchain protocol"
    - "bitcoin meets strong consistency"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-2 (induced by source paper "redactable blockchain in the permissionless setting"):
  with members:
    - "decentralized trusted timestamping using the crypto currency bitcoin"
    - "modeling bitcoin contracts by timed automata"
    - "majority is not enough bitcoin mining is vulnerable"

Connected through hyperedge HE-3 (induced by source paper "erasing data from blockchain nodes"):
  with members:
    - "redactable blockchain in the permissionless setting"
    - "a survey on security and privacy issues of bitcoin"

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)