An Efficient Hierarchical Identity-Based Encryption Scheme for the Key Escrow

摘要

Hierarchical Identity-Based Encryption (HIBE) is a generalization of Identity-Based Encryption (IBE) that mirrors an organizational hierarchy, however, the residual key escrow problem has still remained. This paper introduces a new scheme, based on the security notion of anonymous ciphertext indistinguishability against key generation center (ACI-KGC) security proposed by Chow, to remove the inherent key escrow problem. The scheme employs multiple Identity Certification Authorities (ICAs) which can ensure that the Private Key Generators (PKGs) distribute private key without knowing the list of user's identity information, so as to prevent malicious PKGs from decrypting message on behalf of user or maliciously make user's private key public. Security analysis shows that the scheme can solve the key escrow with keeping the high-efficiency and security of HIBE system. In contrast to Chen's T-HIBE and Chow's scheme, to generating the user's private key, our scheme does not require the multiple KPAs or the complex interactive protocol which take too much extra computation costs. And comparing with GS-HIBE, our scheme focuses on solving the key escrow problem with outstanding performance and security of HIBE system.