Cryptanalysis of a Fuzzy Identity Based Encryption Scheme in the Standard Model

Article type: Research Article

Authors: Wang, Xu An | Yang, Xiaoyuan | Zhang, Minqing | Yu, Yong

Affiliations: Key Laboratory of Information and Network Security, Engineering University of Chinese Armed Police Force, Xi'an 710086, P.R. China, e-mail: [email protected] | School of Computer Science and Engineering, University of Electronic Science and Technology of China, Chengdu 610054, P.R. China

Abstract: Fuzzy identity based encryption (FIBE), proposed by Sahai and Waters, is a new kind of identity based encryption. It allows users with identity w can decrypt ciphertext for w' if and only if w is close enough to w'. Recently, Ren et al. proposed a new FIBE scheme and claimed it is fully CCA2 secure in the standard model with a tight reduction. However, in this paper we will show that their scheme is not correct. Furthermore, the key generation process of their scheme cannot resist the collusion attack, which is a basic security requirement for FIBE. At last, we propose a new fully secure FIBE scheme based on the Sahai–Waters FIBE scheme and prove its security by using the “dual system encryption” technique.

Keywords: cryptography, fuzzy identity based encryption, fully secure, CCA2-secure, attack

Journal: Informatica, vol. 23, no. 2, pp. 299-314, 2012