Efficient generic construction of CCA-secure identity-based encryption from randomness extraction

We propose a generic construction that yields efficient identity-based encryption (IBE) schemes secure against chosen ciphertext attack (CCA) in the standard model. Our construction extends Kiltz et al.'s (Eurocrypt '09) method of constructing CCA-secure public-key encryption schemes via randomness extraction to the identity-based setting. The main idea of our construction is to transform 'ϵ1-almost κ-entropic' and valid/invalid ciphertext indistinguishable (VI-IND) identity-based hash proof system to the one that satisfies the stronger 'ϵ2-universal' and VI-IND property. This transformation is realized by a randomness extractor based on the 4-wise hash function.We demonstrate that our generic construction can produce CCA-secure IBE schemes whose efficiency is comparable with the most efficient but non-generic CCA-secure IBE schemes without random oracles in the literature.