ABSTRACT
This chapter starts with the proof of security of Identity-Based Encryption (IBE) scheme using the partitioning approach causing loose reduction. It dedicates to the Gentry’s IBE that has certain advantages over previous schemes in terms of computational efficiency, shorter public parameters, recipient anonymity, and tight security reduction. In 2006, Gentry proposed the IBE scheme that is fully secure without random oracles and has several advantages over previous such systems. The security of Gentry’s scheme is based on the assumption that the truncated decision q-ABDHE problem is hard. This is a non-static hardness assumption where the size of an instance depends on some parameter of the scheme.
