Server-Aided Hierarchical Identity-Based Encryption

Hierarchical Identity-Based Encryption (HIBE) system is an important cryptographic tools. However, one of the main efficiency drawbacks of HIBE is that the computational cost during encryption phase grows with the depth of identity. Thus, before widely deployed, it is an increasing need to improve its efficiency. Especially, in the cloud computing consisting of mobile devices as information collection nodes, user terminal has too limited computation ability to independently finish basic HIBE operations locally. In this paper, to tackle the challenges above, we introduce outsourcing computation into HIBE to support for efficient encryption for users. We present an HIBE scheme with encryption delegated. With the aid of third party service provider, the proposed scheme not only eliminates overhead computation at users but also protects their privacy.