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: "a ultimate approach of mitigating attacks in rpl based low power lossy networks"
  Abstract: The Routing Protocol for Low-Power and Lossy Networks (RPL) is the existing routing protocol for Internet of Things (IoT). RPL is a proactive,lightweight, Distance Vector protocol which offers security against various forms of routing attacks. Still, there are various attacks(as rank, version attacks and many more ) which is possible in this network due to problem of unauthenticated or unencrypted control frames, centralized root controller, compromised or unauthenticated devices and many more ways. There are various solutions present in the literature but every solution has its pros and cons. There is no appropriate system framework till now which completely solves these all issues. So, we present a ultimate approach to mitigate these RPL attacks more efficiently and effectively. We use IDS based system for internal attacks and a mini-firewall for removing the external attacks. In IDS based approach, we use intrusion detection system at multiple locations for analyzing the behaviour of nodes. The final decision whether the node is attacker or not depends on mainly three things as: trust between the neighbouring nodes, local decision by multiple sink nodes and global decision by root node. We also use some blockchain features in this framework for better internal security. We use some threshold values and rules in mini-firewall for removing external attacks. In this paper, we provide the proposed approach and theoretical analysis of this approach which provide better protection from these attacks than any other method.

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)