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: "vespa vehicular security and privacy preserving architecture"
  Abstract: Vehicular Communications (VC) are reaching a near deployment phase and will play an important role in improving road safety, driving efficiency and comfort. The industry and the academia have reached a consensus for the need of a Public Key Infrastructure (PKI), in order to achieve security, identity management, vehicle authentication, as well as preserve vehicle privacy. Moreover, a gamut of proprietary and safety applications, such as location-based services and pay-as-you-drive systems, are going to be offered to the vehicles. The emerging applications are posing new challenges for the existing Vehicular Public Key Infrastructure (VPKI) architectures to support Authentication, Authorization and Accountability (AAA), without exposing vehicle privacy. In this work we present an implementation of a VPKI that is compatible with the VC standards. We propose the use of tickets as cryptographic tokens to provide AAA and also preserve vehicle privacy against adversaries and the VPKI. Finally, we present the efficiency results of our implementation to prove its applicability.

Connected through hyperedge HE-1 (induced by source paper "resilient privacy protection for location based services through decentralization"):
  with members:
    - "resilient collaborative privacy for location based services"
    - "efficient scalable and resilient vehicle centric certificate revocation list distribution in vanets"
    - "secmace scalable and robust identity and credential management infrastructure in vehicular communication systems"
    - "towards deploying a scalable robust vehicular identity and credential management infrastructure"
    - "geo indistinguishability differential privacy for location based systems"
    - "secure vehicular communication systems design and architecture"

Connected through hyperedge HE-2 (induced by source paper "private authentication optimal information theoretic schemes"):
  with members:
    - "controllable identifier measurements for private authentication with secret keys"
    - "the capacity of private information retrieval"
    - "utility privacy tradeoffs in databases an information theoretic approach"
    - "using the physical layer for wireless authentication in time variant channels"

Connected through hyperedge HE-3 (induced by source paper "secmace scalable and robust identity and credential management infrastructure in vehicular communication systems"):
  with members:
    - "resilient privacy protection for location based services through decentralization"
    - "security and privacy in vehicular social networks"
    - "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 implementation performance and research challenges"
    - "impact of vehicular communications security on transportation safety"

Connected through hyperedge HE-4 (induced by source paper "security and privacy in vehicular social networks"):
  with members:
    - "resilient collaborative privacy for location based services"
    - "the key to intelligent transportation identity and credential management in vehicular communication systems"
    - "towards deploying a scalable robust vehicular identity and credential management infrastructure"
    - "secure vehicular communication systems design and architecture"

Connected through hyperedge HE-5 (induced by source paper "evaluating on demand pseudonym acquisition policies in vehicular communication systems"):
  with members:
    - "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-6 (induced by source paper "the key to intelligent transportation identity and credential management in vehicular communication systems"):
  with members:
    - "towards deploying a scalable robust vehicular identity and credential management infrastructure"
    - "on the road reflections on the security of vehicular communication systems"
    - "impact of vehicular communications security on transportation safety"
    - "secure vehicular communication systems design and architecture"

Connected through hyperedge HE-7 (induced by source paper "towards deploying a scalable robust vehicular identity and credential management infrastructure"):
  with members:
    - "on the road reflections on the security of vehicular communication systems"
    - "impact of vehicular communications security on transportation safety"
    - "secure vehicular communication systems design and architecture"

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)