Paper 2010/210

Fully Secure Identity-Based Encryption Without Random Oracles: A variant of Boneh-Boyen HIBE

Yu Chen

Abstract

We present an Identity-Based Encryption (IBE) scheme that is fully secure without random oracles and has several advantages over previous such schemes - namely, computational efficiency, shorter public parameters, and simple assumption. The construction is remarkably simple and the security reduction is straightforward. We first give our CPA construction based on the decisional Bilinear Diffie-Hellman (BDH) problem, then archiving the CCA security by employing secure symmetric-key encryption algorithm. Additionally, we transform the CPA construction into a new signature scheme that is secure under the computational Diffie-Helleman assumption without random oracles.