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: "ledakem a post quantum key encapsulation mechanism based on qc ldpc codes"
  Abstract: This work presents a new code-based key encapsulation mechanism (KEM) called LEDAkem. It is built on the Niederreiter cryptosystem and relies on quasi-cyclic low-density parity-check codes as secret codes, providing high decoding speeds and compact keypairs. LEDAkem uses ephemeral keys to foil known statistical attacks, and takes advantage of a new decoding algorithm that provides faster decoding than the classical bit-flipping decoder commonly adopted in this kind of systems. The main attacks against LEDAkem are investigated, taking into account quantum speedups. Some instances of LEDAkem are designed to achieve different security levels against classical and quantum computers. Some performance figures obtained through an efficient C99 implementation of LEDAkem are provided.

Connected through hyperedge HE-1 (induced by source paper "analysis of the error correction capability of ldpc and mdpc codes under parallel bit flipping decoding and application to cryptography"):
  with members:
    - "analysis of reaction and timing attacks against cryptosystems based on sparse parity check codes"
    - "the decoding failure probability of mdpc codes"
    - "hindering reaction attacks by using monomial codes in the mceliece cryptosystem"
    - "security and complexity of the mceliece cryptosystem based on quasi cyclic low density parity check codes"
    - "on the guaranteed error correction capability of ldpc codes"

Connected through hyperedge HE-2 (induced by source paper "encryption scheme based on expanded reed solomon codes"):
  with members:
    - "generalization of the ball collision algorithm"
    - "variations of the mceliece cryptosystem"
    - "cryptanalysis of mceliece cryptosystem based on algebraic geometry codes and their subcodes"
    - "polynomial time attack on wild mceliece over quadratic extensions"
    - "distinguisher based attacks on public key cryptosystems using reed solomon codes"
    - "an efficient attack of a mceliece cryptosystem variant based on convolutional codes"
    - "a distinguisher based attack on a variant of mceliece s cryptosystem based on reed solomon codes"
    - "cryptanalysis of two mceliece cryptosystems based on quasi cyclic codes"

Connected through hyperedge HE-3 (induced by source paper "analysis of reaction and timing attacks against cryptosystems based on sparse parity check codes"):
  with members:
    - "the decoding failure probability of mdpc codes"
    - "assessing and countering reaction attacks against post quantum public key cryptosystems based on qc ldpc codes"
    - "hindering reaction attacks by using monomial codes in the mceliece cryptosystem"

Connected through hyperedge HE-4 (induced by source paper "assessing and countering reaction attacks against post quantum public key cryptosystems based on qc ldpc codes"):
  with members:
    - "security and complexity of the mceliece cryptosystem based on quasi cyclic low density parity check codes"

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)