Identity-based proxy re-encryption schemes have been proposed to shift the burden of managing numerous files from the owner to a proxy server. Nevertheless, the existing solutions suffer from several drawbacks. First, the access permission is determined by the central authority, which makes the scheme impractical. Second, they are insecure against collusion attacks. Finally, only queries from the same domain (intra-domain) are considered. We note that one of the main applications of identity-based proxy re-encryption schemes is in the cloud computing scenario. Nevertheless, in this scenario, users in different domains can share files with each other. Therefore, the existing solutions do not actually solve the motivating scenario, when the scheme is applicable for cloud computing. Hence, it remains an interesting and challenging research problem to design an identity-based data storage scheme which is secure against collusion attacks and supports intra-domain and inter-domain queries. In this paper, we propose an identity-based data storage scheme where both queries from the intra-domain and inter-domain are considered and collusion attacks can be resisted. Furthermore, the access permission can be determined by the owner independently. © 2012 Elsevier B.V. All rights reserved.