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: "naturally rehearsing passwords"
  Abstract: We introduce quantitative usability and security models to guide the design of password management schemes --- systematic strategies to help users create and remember multiple passwords. In the same way that security proofs in cryptography are based on complexity-theoretic assumptions (e.g., hardness of factoring and discrete logarithm), we quantify usability by introducing usability assumptions. In particular, password management relies on assumptions about human memory, e.g., that a user who follows a particular rehearsal schedule will successfully maintain the corresponding memory. These assumptions are informed by research in cognitive science and validated through empirical studies. Given rehearsal requirements and a user's visitation schedule for each account, we use the total number of extra rehearsals that the user would have to do to remember all of his passwords as a measure of the usability of the password scheme. Our usability model leads us to a key observation: password reuse benefits users not only by reducing the number of passwords that the user has to memorize, but more importantly by increasing the natural rehearsal rate for each password. We also present a security model which accounts for the complexity of password management with multiple accounts and associated threats, including online, offline, and plaintext password leak attacks. Observing that current password management schemes are either insecure or unusable, we present Shared Cues--- a new scheme in which the underlying secret is strategically shared across accounts to ensure that most rehearsal requirements are satisfied naturally while simultaneously providing strong security. The construction uses the Chinese Remainder Theorem to achieve these competing goals.

Connected through hyperedge HE-1 (induced by source paper "bicycle attacks considered harmful quantifying the damage of widespread password length leakage"):
  with members:
    - "spaced repetition and mnemonics enable recall of multiple strong passwords"
    - "cash a cost asymmetric secure hash algorithm for optimal password protection"
    - "can t you hear me knocking identification of user actions on android apps via traffic analysis"
    - "calibrating data to sensitivity in private data analysis"
    - "de anonymizing social networks"

Connected through hyperedge HE-2 (induced by source paper "usability of humanly computable passwords"):
  with members:
    - "spaced repetition and mnemonics enable recall of multiple strong passwords"
    - "towards human computable passwords"

Connected through hyperedge HE-3 (induced by source paper "changing users security behaviour towards security questions a game based learning approach"):
  with members:
    - "security strength indicator in fallback authentication nudging users for better answers in secret questions"
    - "data driven authentication on the effectiveness of user behaviour modelling with mobile device sensors"

Connected through hyperedge HE-4 (induced by source paper "a gamified approach to improve users memorability of fall back authentication"):
  with members:
    - "security strength indicator in fallback authentication nudging users for better answers in secret questions"
    - "data driven authentication on the effectiveness of user behaviour modelling with mobile device sensors"

Connected through hyperedge HE-5 (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"
    - "optimizing password composition policies"
    - "calibrating data to sensitivity in private data analysis"

Connected through hyperedge HE-6 (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"
    - "gotcha password hackers"
    - "optimizing password composition policies"

Connected through hyperedge HE-7 (induced by source paper "spaced repetition and mnemonics enable recall of multiple strong passwords"):
  with members:
    - "optimizing password composition policies"
    - "the online laboratory conducting experiments in a real labor market"

Connected through hyperedge HE-8 (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"
    - "gotcha password hackers"
    - "optimizing password composition policies"
    - "on the complexity of random satisfiability problems with planted solutions"

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)