Aiming at tackling the challenges above, for the first time, we propose a Secure Outsourced ABE system, which not only supports secure outsourced decryption, but also provides secure outsourced key-issuing. Unlike the current outsourced ABE systems, our new method offloads all access policy and attribute related operations in the key-issuing process or decryption to a Key Generation Service Provider (KGSP) and a Decryption Service Provider (DSP), respectively, leaving only a constant number of simple operations for the AAs and eligible users to perform locally. Furthermore, we show that both outsourcing processes (to KGSP and to DSP) are secure, namely, the KGSP and the DSP would not be able to recover the keys or decrypt the ciphertexts, respectively.
In addition, we consider the scenario that a KGSP or DSP may be dishonest and could maliciously generate some incorrect returning values rather than following the outsourced operations. Therefore, in this paper, we also propose another ABE construction which allows the AAs and eligible users to check the correctness of outsourced operations in an efficient way. The security of the construction is analyzed under a recently formalized model called Refereed Delegation of Computation (RDoC).Category / Keywords: public-key cryptography / Attribute-based encryption, access control, outsourcing computation, cloud computing, checkability Date: received 7 Nov 2012, last revised 30 Mar 2013, withdrawn 30 Mar 2013 Contact author: jinli71 at gmail com; lijw1987@gmail com Available format(s): (-- withdrawn --) Version: 20130331:042334 (All versions of this report) Short URL: ia.cr/2012/635 Discussion forum: Show discussion | Start new discussion