Anonymous attribute-based encryption supporting efficient decryption test

Attribute-based encryption (ABE) has been widely studied recently to support fine-grained access control of shared data. Anonymous ABE, which is a relevant notion to ABE, further hides the receivers' attribute information in ciphertexts because many attributes are sensitive and related to the identity of eligible users. However, in existing anonymous ABE work, a user knows whether the attributes and the policy match or not only after repeating decryption attempts. And, the computation overhead of each decryption is high as the computational cost grows with the complexity of the access formula, which usually requires many pairings in most of the existing ABE schemes. As a result, this direct decryption method in anonymous ABE will suffer a severe efficiency drawback. Aiming at tackling the challenge above, we propose a novel technique called match-then-decrypt, in which a matching phase is additionally introduced before the decryption phase. This technique works by computing special components in ciphertexts, which are used to perform the test that if the attribute private key matches the hidden attributes policy in ciphertexts without decryption. In our proposed construction, the computation cost of such a test is much less than one decryption operation. The proposed construction is proven to be secure. In addition, the results in simulation experiments indicate that the proposed solution is efficient and practical, which greatly improves the efficiency of decryption in anonymous ABE. © 2013 ACM.