Hierarchical Certificate-Based Encryption: Definition and an Efficient Construction

Certificate-based encryption is a new paradigm which was introduced by Gentry to address the complex public key revocation problem in traditional public key cryptosystems. It represents an interesting and potentially useful balance between traditional public-key encryption and identity-based encryption. In this paper, we introduce the notion of hierarchical certificate-based encryption that preserves the advantages of certificate-based encryption such as implicit certificate and key-escrow free while inheriting the properties of hierarchical identity-based encryption. We formalize the definition of hierarchical certificate-based encryption and also propose a concrete hierarchical certificate-based encryption scheme that is chosen-ciphertext secure under the hardness of bilinear Diffie-Hellman problem in the random oracle model.