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: "Ciphertext-Policy Attribute-Based Encryption with User Revocation Support"
  Abstract: In Ciphertext-Policy Attribute-Based Encryption(CP-ABE) schemes, the encryptor may set the policy in such a way that who can decrypt the encrypted message. The policy may be formed with the help of attributes. Recent CP-ABE schemes are constructed based on Linear Secret Sharing Scheme. In this paper, we use the Linear Integer Secret Sharing Scheme (LISS) for the construction. Lewko et al.[7] proposed a direction revocation method, based on that we then present a construction of CP-ABE scheme with the ability to do the direct revocation of user. The proposed construction is selectively secure under Decision Bilinear Diffe-Hellman assumption.

Connected through hyperedge HE-1 (induced by source paper "Conjunctive Broadcast and Attribute-Based Encryption"):
  with members:
    - "Collusion resistant broadcast encryption with short ciphertexts and private keys"
    - "Functional encryption for inner product predicates from learning with errors"

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