human: Given a node-centered hypergraph: <hypergraph>, where nodes represent authors and hyperedges represent groups of authors who co-authored the same paper.

Details of the hypergraph:
Center node: "Analyses of Crypto Module for Gbps VPN System"
  Abstract: A VPN is widely used in a communications environment which access is controlled to permit peer connections only within a defined community of interest. It is constructed through some form of partitioning of a common underlying communication medium, where this underlying communications medium provides services to the network on a non-exclusive basis. In this paper, we have analyzed a variety of architecture to implement Giga bps VPN system. The proposed architecture will satisfy the needs of clients who adopt Giga bps VPN system in the various environments.

Connected through hyperedge HE-1 (induced by source paper "Parts-Based Feature Extraction of Spectrum of Speech Signal Using Non-Negative Matrix Factorization"):
  with members:
    (none)

Question: Please tell me which research area the center author belongs to. The 4 classes are: Computer science, Mathematics, Engineering, Economics, Psychology, Business. Directly output the class name.

gpt: Computer science