human: Given a hyperedge-centered hypergraph: <hypergraph>, where the center hyperedge groups authors who co-authored the same paper.

Details of the hypergraph:
Center hyperedge (induced by source paper "Dual System Encryption: Realizing Fully Secure IBE and HIBE under Simple Assumptions"):
  Abstract: We present a new methodology for proving security of encryption systems using what we call Dual System Encryption. Our techniques result in fully secure Identity-Based Encryption (IBE) and Hierarchical Identity-Based Encryption (HIBE) systems under the simple and established decisional Bilinear Diffie-Hellman and decisional Linear assumptions. Our IBE system has ciphertexts, private keys, and public parameters each consisting of a constant number of group elements. These results are the first HIBE system and the first IBE system with short parameters under simple assumptions.

In a Dual System Encryption system both ciphertexts and private keys can take on one of two indistinguishable forms. A private key or ciphertext will be normal if they are generated respectively from the system's key generation or encryption algorithm. These keys and ciphertexts will behave as one expects in an IBE system. In addition, we define semi-functional keys and ciphertexts. A semi-functional private key will be able to decrypt all normally generated ciphertexts; however, decryption will fail if one attempts to decrypt a semi-functional ciphertext with a semi-functional private key. Analogously, semi-functional ciphertexts will be decryptable only by normal private keys.

Dual System Encryption opens up a new way to prove security of IBE and related encryption systems. We define a sequence of games where we change first the challenge ciphertext and then the private keys one by one to be semi-functional. We finally end up in a game where the challenge ciphertext and all private keys are semi-functional at which point proving security is straightforward.

Includes members:
  Member "Collusion resistant broadcast encryption with short ciphertexts and private keys":
    also connected through other hyperedges:
      - Hyperedge HE-1 (induced by source paper "Pairing-Based cryptography at high security levels")
  Member "Achieving fine-grained access control for secure data sharing on cloud servers":
    also connected through other hyperedges:
      - Hyperedge HE-2 (induced by source paper "Building access control policy model for privacy preserving and testing policy conflicting problems")
  Member "Functional encryption for inner product predicates from learning with errors":
    also connected through other hyperedges:
      - Hyperedge HE-3 (induced by source paper "Fully secure functional encryption with general relations from the decisional linear assumption")
  Member "Fully secure functional encryption with general relations from the decisional linear assumption":
    also connected through other hyperedges:
      - Hyperedge HE-4 (induced by source paper "Functional Encryption with Bounded Collusions via Multi-party Computation")
  Member "New chosen-ciphertext secure identity-based encryption with tight security reduction to the bilinear Diffie-Hellman problem":
    also connected through other hyperedges:
      (none)

Question: Please tell me which research area the co-authored paper (i.e., the source paper of the center hyperedge) belongs to. The 4 classes are: Computer science, Mathematics, Engineering, Economics, Psychology, Business. Directly output the class name.

gpt: Computer science