A unidirectional conditional proxy re-encryption scheme based on non-monotonic access structure

A unidirectional conditional proxy re-encryption scheme based on non-monotonic access structure Bin Wang Information Engineering College of Yangzhou University No.196 West HuaYang Road, Yangzhou City, Jiangsu Province, P.R.China E-mail: [email protected] Abstract: Recently, Fang et al. [6] introduced an interactive(bidirectional) conditional proxy re-encryption(C-PRE) scheme such that a proxy can only convert ciphertexts that satisfy access policy set by a delegator. Their scheme supports monotonic access policy expressed by “OR” and “AND” gates. In addition, their scheme is called interactive since generation of re-encryption keys requires interaction between the delegator and delegatee. In this paper, we study the problem of constructing a unidirectional(non-interactive) C-PRE scheme supporting non-monotonic access policy expressed by “NOT”, “OR” and “AND” gates. A security model for unidirectional C-PRE schemes is also proposed in this paper. To yield a unidirectional C-PRE scheme supporting non-monotonic access policy, we extend the unidirectional PRE scheme presented by Libert et al. [8] by using the ideas from the non-monotonic attributed based encryption (ABE) scheme presented by Ostrovsky et al. [9]. Furthermore, the security of our C-PRE scheme is proved under the modified 3-weak Decision Bilinear Diffie-Hellman Inversion assumption in the standard model.