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: "smartotps an air gapped 2 factor authentication for smart contract wallets"
  Abstract: With the recent rise of cryptocurrencies, the security and management of crypto-tokens have become critical. We have witnessed many attacks on users, their software, or their providers, which have resulted in significant financial losses. To remedy these issues, many wallet solutions have been proposed to store users' crypto-tokens. However, these solutions often lack either essential security features, usability, or do not allow users to customize their spending rules.  In this paper, we propose SmartOTPs, a smart-contract cryptocurrency wallet framework that gives a flexible, usable, and secure way of managing crypto-tokens in a self-sovereign (i.e., non-custodial) fashion. The proposed framework consists of four components (i.e., a client, a private key hardware wallet, a smart contract, and an authenticator) and provides 2-factor authentication performed in two stages of interaction with the blockchain. To the best of our knowledge, our framework is the first one that utilizes one-time passwords (OTPs) in the setting of the public blockchain. OTPs are aggregated by a Merkle tree and hash chains in such a way that for every authentication only a 16B-long OTP is transferred from the authenticator to the client. Such a novel setting enables us to make a fully air-gapped authenticator utilizing transcription of mnemonic words, while additionally offering resilience against quantum cryptanalysis. We have made a proof-of-concept basing on the Ethereum platform. A cost analysis of our implementation shows that the average cost of a transfer operation is comparable to existing 2-factor authentication solutions using smart contracts with multi-signatures.  In contrast to the previous version of our work \cite{homoliak2018air}, we change the protocol to utilize a hardware wallet with a display, enabling us to protect against the attacker that tampers with the client.

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)