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: "optimizing password composition policies"
  Abstract: A password composition policy restricts the space of allowable passwords to eliminate weak passwords that are vulnerable to statistical guessing attacks. Usability studies have demonstrated that existing password composition policies can sometimes result in weaker password distributions; hence a more principled approach is needed. We introduce the first theoretical model for optimizing password composition policies. We study the computational and sample complexity of this problem under different assumptions on the structure of policies and on users' preferences over passwords. Our main positive result is an algorithm that -- with high probability --- constructs almost optimal policies (which are specified as a union of subsets of allowed passwords), and requires only a small number of samples of users' preferred passwords. We complement our theoretical results with simulations using a real-world dataset of 32 million passwords.

Connected through hyperedge HE-1 (induced by source paper "passlab a password security tool for the blue team"):
  with members:
    - "investigating the distribution of password choices"

Connected through hyperedge HE-2 (induced by source paper "client cash protecting master passwords against offline attacks"):
  with members:
    - "spaced repetition and mnemonics enable recall of multiple strong passwords"
    - "cash a cost asymmetric secure hash algorithm for optimal password protection"
    - "naturally rehearsing passwords"
    - "calibrating data to sensitivity in private data analysis"

Connected through hyperedge HE-3 (induced by source paper "cash a cost asymmetric secure hash algorithm for optimal password protection"):
  with members:
    - "client cash protecting master passwords against offline attacks"
    - "spaced repetition and mnemonics enable recall of multiple strong passwords"
    - "naturally rehearsing passwords"
    - "gotcha password hackers"

Connected through hyperedge HE-4 (induced by source paper "spaced repetition and mnemonics enable recall of multiple strong passwords"):
  with members:
    - "naturally rehearsing passwords"
    - "the online laboratory conducting experiments in a real labor market"

Connected through hyperedge HE-5 (induced by source paper "towards human computable passwords"):
  with members:
    - "spaced repetition and mnemonics enable recall of multiple strong passwords"
    - "analysis of boolean functions"
    - "human computable passwords"
    - "naturally rehearsing passwords"
    - "gotcha password hackers"
    - "on the complexity of random satisfiability problems with planted solutions"

Connected through hyperedge HE-6 (induced by source paper "naturally rehearsing passwords"):
  with members:
    - "you had me at hello how phrasing affects memorability"

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)