CCA-secure IB-KEM from identity-based extractable hash proof system

In this paper, we introduce a general paradigm called identity-based extractable hash proof system (IB-EHPS), which is an extension of extractable hash proof system (EHPS) proposed by Wee (CRYPTO'10). We show how to construct identity-based key encapsulation mechanism (IB-KEM) from IB-EHPS in a simple and modular fashion. Our construction provides a generic method of building and interpreting CCA-secure IB-KEMs based on computational assumptions. As instantiations, we realize IB-EHPS from the bilinear Diffie-Hellman assumption and the modified bilinear Diffie-Hellman assumption, respectively. Besides, we carefully investigate the relation between EHPS and IB-EHPS, and indicate possible refinement and generalization of EHPS.