Fully Secure Anonymous Identity-Based Encryption under Simple Assumptions

Anonymous identity-based encryption systems can be used to protect users´ privacy and construct Public key Encryption with Keyword Search (PEKS) schemes where the ciphertext does not leak the identity of the recipient. Currently, there is no anonymous IBE scheme that is fully secure under simple assumptions without random oracles. In this paper, we propose an anonymous IBE scheme using the approach of Dual System Encryption. The scheme is fully secure without random oracles based on decisional bilinear Diffie-Hellman (BDH) and linear assumptions, and the security reduction is tight. These two assumptions are simple and our scheme is more secure than the previous anonymous IBE schemes.