Private Key Management in Hierarchical Identity-Based Encryption

Hierarchical identity-based encryption (HIBE) is a generalization of IBE that mirrors an organizational hierarchy, which consists of a root private key generator (PKG), domain PKGs and users. In a traditional HIBE system, users retrieve private keys from their domain PKGs, while domain PKGs request domain secret keys from the root PKG. What´s more, the manager of each private key is a single one. Unfortunately, some of the PKGs (private key manager) could be untrusty, such that they would leak lower level´s private keys. In this paper, we propose a novel private key management scheme in HIBE, where a domain master key is not charged by a single one, buta group PKGs aiming at avoiding unreliable PKGs´ attack.