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: "Civitas: Toward a Secure Voting System"
  Abstract: Civitas is the first electronic voting system that is coercion-resistant, universally and voter verifiable, and suitable for remote voting. This paper describes the design and implementation of Civitas. Assurance is established in the design through security proofs, and in the implementation through information-flow security analysis. Experimental results give a quantitative evaluation of the tradeoffs between time, cost, and security.

Connected through hyperedge HE-1 (induced by source paper "eVoting with the European Citizen Card."):
  with members:
    (none)

Connected through hyperedge HE-2 (induced by source paper "Practical Byzantine fault tolerance"):
  with members:
    - "Proactive recovery in a Byzantine-fault-tolerant system"
    - "A study of the internal and external effects of concurrency bugs"
    - "Performance study of Byzantine Agreement Protocol with artificial neural network"
    - "Preserving peer replicas by rate-limited sampled voting"

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