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: "propyla privacy preserving long term secure storage"
  Abstract: The amount of electronically stored information increases rapidly. Sensitive information requires integrity and confidentiality protection, sometimes for decades or even centuries (e.g., health records or governmental documents). Commonly used cryptographic schemes, however, are not designed to provide protection over such long time periods. Their security usually relies on the hardness of a specific computational problem and security cannot be maintained against unforeseeable developments in computational technology (e.g., quantum computers breaking RSA-based systems). Recently, Braun et al.\ (\mboxAsiaCCS'17 ) proposed the first storage architecture that supports integrity protection renewal while guaranteeing information theoretic confidentiality. However, their solution only considers the storage of unstructured data and does not allow for reading or writing subparts of the data.    Our contribution is the first long-term secure storage architecture that supports storage of structured databases and provides long-term integrity, confidentiality, and access pattern hiding security. To achieve this, we combine several cryptographic components (i.e., secret sharing, renewable timestamps, and renewable commitments) with an information-theoretically secure \mboxORAM such that the described security properties are achieved. We also prove our construction secure and show that it only introduces a small overhead compared to standard secret sharing and ORAM based storage solutions.

Connected through hyperedge HE-1 (induced by source paper "elsa efficient long term secure storage of large datasets"):
  with members:
    - "mops a modular protection scheme for long term storage"

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)