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: "non commutative digital signatures"
  Abstract: The objective of this work is to survey several digital signatures proposed in the last decade using non-commutative groups and rings and propose a digital signature using non-commutative groups and analyze its security.

Connected through hyperedge HE-1 (induced by source paper "the hidden subgroup problem and post quantum group based cryptography"):
  with members:
    - "the status of polycyclic group based cryptography a survey and open problems"
    - "using semidirect product of semi groups in public key cryptography"
    - "cryptography with right angled artin groups"
    - "public key exchange using semidirect product of semi groups"
    - "quantum computation and lattice problems"

Connected through hyperedge HE-2 (induced by source paper "the status of polycyclic group based cryptography a survey and open problems"):
  with members:
    - "polynomial time solutions of computational problems in noncommutative algebraic cryptography"
    - "a secret sharing scheme based on group presentations and the word problem"
    - "zero knowledge authentication schemes from actions on graphs groups or rings"
    - "length based attacks for certain group based encryption rewriting systems"

Connected through hyperedge HE-3 (induced by source paper "heisenberg groups as platform for the aag key exchange protocol"):
  with members:
    - "length based cryptanalysis the case of thompson s group"
    - "length based attacks for certain group based encryption rewriting systems"

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)