Chosen-ciphertext security from identity-based encryption

We propose simple and efficient CCA-secure public-key encryption schemes (i.e., schemessecure against adaptive chosen-ciphertext attacks) based on any identity-based encryption (IBE)
scheme. Our constructions have ramifications of both theoretical and practical interest. First,
our schemes give a new paradigm for achieving CCA-security; this paradigm avoids “proofs of
well-formedness” that have been shown to underlie previous constructions. Second, instantiating
our construction using known IBE constructions we obtain CCA-secure encryption schemes
whose performance is competitive with the most efficient CCA-secure schemes to date.
Our techniques extend naturally to give an efficient method for securing IBE schemes (even
hierarchical ones) against adaptive chosen-ciphertext attacks. Coupled with previous work, this
gives the first efficient constructions of CCA-secure IBE schemes.