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: "the piggy bank cryptographic trope"
  Abstract: This paper presents applications of the trope of the locked and sealed piggy-bank into which the secret can be easily inserted but from which it cannot be withdrawn without opening the box. We present a basic two-pass cryptographic scheme that can serve as template for a variety of implementations. Together with the sealed piggy-bank is sent a coded letter that lists and certifies the contents of the box. We show how this idea can help increase the security of cryptographic protocols for classical systems as well as those based on "single-state" systems. More specifically, we propose the use of a hashing digest (instead of the coded letter) to detect loss of key bits to the eavesdropper and use in communication systems where error correction is an important issue.

Connected through hyperedge HE-1 (induced by source paper "secret sharing with trusted third parties using piggy bank protocol"):
  with members:
    - "a piggybank protocol for quantum cryptography"
    - "authentication using piggy bank approach to secure double lock cryptography"

Connected through hyperedge HE-2 (induced by source paper "multiparty probability computation and verification"):
  with members:
    - "a review of man in the middle attacks"
    - "oblivious transfer protocol with verification"
    - "generating primes using partitions"
    - "a survey of p2p network security"
    - "survey of sybil attacks in social networks"

Connected through hyperedge HE-3 (induced by source paper "a review of man in the middle attacks"):
  with members:
    - "a survey of p2p network security"
    - "authentication using piggy bank approach to secure double lock cryptography"
    - "public key infrastructure based on authentication of media attestments"

Connected through hyperedge HE-4 (induced by source paper "coding side information for implementing cubic transformation"):
  with members:
    - "a review of man in the middle attacks"
    - "a survey of p2p network security"
    - "survey of sybil attacks in social networks"

Connected through hyperedge HE-5 (induced by source paper "generating primes using partitions"):
  with members:
    - "a survey of p2p network security"

Connected through hyperedge HE-6 (induced by source paper "a survey of p2p network security"):
  with members:
    - "understanding the properties of the bittorrent overlay"

Connected through hyperedge HE-7 (induced by source paper "analysis of digital knapsack based sealed bid auction"):
  with members:
    - "generalized public key transformations with side information"
    - "ascending auctions and walrasian equilibrium"
    - "a novel approach to fully private and secure auction a sealed bid knapsack auction"
    - "selling privacy at auction"

Connected through hyperedge HE-8 (induced by source paper "survey of key distribution schemes for wireless sensor networks"):
  with members:
    - "random residue sequences and the number theoretic hilbert transform"
    - "a key set cipher for wireless sensor networks"
    - "randomness of d sequences via diehard testing"
    - "watermarking using decimal sequences"

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)