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: "cryptographic enforcement of information flow policies without public information"
  Abstract: Cryptographic access control has been studied for over 30 years and is now a mature research topic. When symmetric cryptographic primitives are used, each protected resource is encrypted and only authorized users should have access to the encryption key. By treating the keys themselves as protected resources, it is possible to develop schemes in which authorized keys are derived from the keys explicitly assigned to the user's possession and publicly available information. It has been generally assumed that each user would be assigned a single key from which all other authorized keys would be derived. Recent work has challenged this assumption by developing schemes that do not require public information, the trade-off being that a user may require more than one key. However, these new schemes, which require a chain partition of the partially ordered set on which the access control policy is based, have some disadvantages. In this paper we define the notion of a tree-based cryptographic enforcement scheme, which, like chain-based schemes, requires no public information. We establish that the strong security properties of chain-based schemes are preserved by tree-based schemes, and provide an efficient construction for deriving a tree-based enforcement scheme from a given policy that minimizes the number of keys required.

Connected through hyperedge HE-1 (induced by source paper "jedi many to many end to end encryption and key delegation for iot"):
  with members:
    - "droplet decentralized authorization for iot data streams"
    - "nucypher kms decentralized key management system"
    - "distributed authorization in vanadium"
    - "privacy discovery and authentication for the internet of things"
    - "riposte an anonymous messaging system handling millions of users"

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)