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: "diffix birch extending diffix aspen"
  Abstract: A longstanding open problem is that of how to get high quality statistics through direct queries to databases containing information about individuals without revealing information specific to those individuals. Diffix is a framework for anonymous database query that adds noise based on the filter conditions in the query. A previous paper described the first version, called diffix-aspen. This version, diffix-birch, extends that description to include a wide variety of common features found in SQL. It describes attacks associated with various features, and the anonymization steps used to defend against those attacks. This paper describes diffix-birch, which was used for the bounty program sponsored by Aircloak starting December 2017.

Connected through hyperedge HE-1 (induced by source paper "averaging attacks on bounded noise based disclosure control algorithms"):
  with members:
    - "linear program reconstruction in practice"
    - "when the signal is in the noise exploiting diffix s sticky noise"
    - "privacy assessment of de identified opal data a report for transport for nsw"
    - "differentially private release of public transport data the opal use case"
    - "concentrated differential privacy"
    - "between pure and approximate differential privacy"
    - "calibrating data to sensitivity in private data analysis"
    - "the power of linear reconstruction attacks"

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)