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 "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 lack either essential security features, or usability, or do not allow users to express their spending rules. #R##N#In this paper, we propose a smart-contract cryptocurrency wallet framework that gives a flexible, usable, and secure way of managing crypto-tokens in a self-sovereign fashion. The proposed framework consists of three components (i.e., an authenticator, a client, and a smart contract) and provides 2-factor authentication performed in two stages of interaction with the blockchain. Our framework utilizes one-time passwords (OTPs) aggregated by a Merkle tree that is distributed across the components in such a way that for every authentication only a single OTP is transferred from the authenticator to the client. Such a novel setting enables us to make a fully air-gapped authenticator with 16B-long OTPs, while offering resilience against quantum cryptanalysis. We implemented our approach basing on the Ethereum cryptocurrency and the Solidity language. We have performed a cost analysis of the implementation and showed that the average cost of a transfer operation is less than $0.15.

Includes members:
  Member "ekiden a platform for confidentiality preserving trustworthy and performant smart contracts":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "on the convergence of artificial intelligence and distributed ledger technology a scoping review and future research agenda")
  Member "rethinking blockchain security position paper":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "a survey on ethereum systems security vulnerabilities attacks and defenses")
  Member "a first look at the usability of bitcoin key management":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "a security reference architecture for blockchains")

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)