Master-Key KDM-Secure ABE via Predicate Encoding 📺
In this paper, we propose the first generic framework for attribute-based encryptions (ABE) with master-secret-key-dependent-message security (mKDM security) for affine functions via predicate encodings by Chen, Gay and Wee [Eurocrypt 2015]. The construction is adaptively secure under standard $k$-Lin assumption in prime-order bilinear groups. By this, we obtain a set of new mKDM-secure ABE schemes with high expressiveness that have never been reached before: we get the first hierarchical IBE (HIBE) scheme and the first ABE scheme for arithmetic branching program (ABP) with mKDM security for affine functions. Thanks to the expressiveness (more concretely, delegability like HIBE), we can obtain mKDM-secure ABE against chosen-ciphertext attack (i.e., CCA security) via a classical CPA-to-CCA transformation that works well in the context of mKDM.