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: "protecting public osn posts from unintended access"
  Abstract: The design of secure and usable access schemes to personal#R##N#data represent a major challenge of online social networks#R##N#(OSNs). State of the art requires prior interaction to grant#R##N#access. Sharing with users who are not subscribed or previously#R##N#have not been accepted as contacts in any case is#R##N#only possible via public posts, which can easily be abused#R##N#by automatic harvesting for user profiling, targeted spearphishing,#R##N#or spamming. Moreover, users are restricted to the#R##N#access rules defined by the provider, which may be overly restrictive,#R##N#cumbersome to define, or insufficiently fine-grained.#R##N#We suggest a complementary approach that can be easily#R##N#deployed in addition to existing access control schemes,#R##N#does not require any interaction, and includes even public,#R##N#unsubscribed users. It exploits the fact that different social#R##N#circles of a user share different experiences and hence encrypts#R##N#arbitrary posts. Hence arbitrary posts are encrypted,#R##N#such that only users with sufficient knowledge about the owner#R##N#can decrypt.#R##N#Assembling only well-established cryptographic primitives,#R##N#we prove that the security of our scheme is determined by#R##N#the entropy of the required knowledge. We consequently#R##N#analyze the efficiency of an informed dictionary attack and#R##N#assess the entropy to be on par with common passwords.#R##N#A fully functional implementation is used for performance#R##N#evaluations, and available for download on the Web.

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.SI(Social and Information Networks)