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: "optimized certificate revocation list distribution for secure v2x communications"
  Abstract: The successful deployment of safe and trustworthy Connected and Autonomous Vehicles (CAVs) will highly depend on the ability to devise robust and effective security solutions to resist sophisticated cyber attacks and patch up critical vulnerabilities. Pseudonym Public Key Infrastructure (PPKI) is a promising approach to secure vehicular networks as well as ensure data and location privacy, concealing the vehicles' real identities. Nevertheless, pseudonym distribution and management affect PPKI scalability due to the significant number of digital certificates required by a single vehicle. In this paper, we focus on the certificate revocation process and propose a versatile and low-complexity framework to facilitate the distribution of the Certificate Revocation Lists (CRL) issued by the Certification Authority (CA). CRL compression is achieved through optimized Bloom filters, which guarantee a considerable overhead reduction with a configurable rate of false positives. Our results show that the distribution of compressed CRLs can significantly enhance the system scalability without increasing the complexity of the revocation process.

Connected through hyperedge HE-1 (induced by source paper "safe d self attestation for networks of heterogeneous embedded devices"):
  with members:
    - "scarr scalable runtime remote attestation for complex systems"
    - "scarr a novel scalable runtime remote attestation"
    - "hydra hybrid design for remote attestation using a formally verified microkernel"
    - "c flat control flow attestation for embedded systems software"

Connected through hyperedge HE-2 (induced by source paper "an optimal security management framework for backhaul aware 5g vehicle to everything v2x"):
  with members:
    - "qos aware routing in wireless networks using aerial vehicles"
    - "a security credential management system for v2x communications"
    - "security management for backhaul aware 5g v2x"

Connected through hyperedge HE-3 (induced by source paper "efficient scalable and resilient vehicle centric certificate revocation list distribution in vanets"):
  with members:
    - "a security credential management system for v2x communications"
    - "rhythm a randomized hybrid scheme to hide in the mobile crowd"
    - "secmace scalable and robust identity and credential management infrastructure in vehicular communication systems"
    - "evaluating on demand pseudonym acquisition policies in vehicular communication systems"
    - "the key to intelligent transportation identity and credential management in vehicular communication systems"
    - "towards deploying a scalable robust vehicular identity and credential management infrastructure"
    - "on the road reflections on the security of vehicular communication systems"
    - "secure vehicular communication systems design and architecture"

Connected through hyperedge HE-4 (induced by source paper "a city scale its g5 network for next generation intelligent transportation systems design insights and challenges"):
  with members:
    - "efficient v2v communication scheme for 5g mmwave hyper connected cavs"
    - "multi radio 5g architecture for connected and autonomous vehicles application and design insights"
    - "agile calibration process of full stack simulation frameworks for v2x communications"
    - "modeling and design of millimeter wave networks for highway vehicular communication"
    - "mmwave system for future its a mac layer approach for v2x beam steering"
    - "harbornet a real world testbed for vehicular networks"

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)