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: "towards practical key exchange from ordinary isogeny graphs"
  Abstract: We revisit the ordinary isogeny-graph based cryptosystems of Couveignes and Rostovtsev-Stolbunov, long dismissed as impractical. We give algorithmic improvements that accelerate key exchange in this framework, and explore the problem of generating suitable system parameters for contemporary pre-and post-quantum security that take advantage of these new algorithms. We also prove the session-key security of this key exchange in the Canetti-Krawczyk model, and the IND-CPA security of the related public-key encryption scheme, under reasonable assumptions on the hardness of computing isogeny walks. Our systems admit efficient key-validation techniques that yield CCA-secure encryp-tion, thus providing an important step towards efficient post-quantum non-interactive key exchange (NIKE).

Connected through hyperedge HE-1 (induced by source paper "stronger and faster side channel protections for csidh"):
  with members:
    - "montgomery curves and their arithmetic"

Connected through hyperedge HE-2 (induced by source paper "pre and post quantum diffie hellman from groups actions and isogenies"):
  with members:
    - "a note on the security of csidh"
    - "mathematics of isogeny based cryptography"
    - "a kilobit hidden snfs discrete logarithm computation"
    - "montgomery curves and their arithmetic"
    - "mu kummer efficient hyperelliptic signatures and key exchange on microcontrollers"
    - "general impossibility of group homomorphic encryption in the quantum world"
    - "an l 1 3 discrete logarithm algorithm for low degree curves"
    - "public key cryptography based on semigroup actions"

Connected through hyperedge HE-3 (induced by source paper "a note on the security of csidh"):
  with members:
    - "improved analysis of kannan s shortest lattice vector algorithm"

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)