\item Our second scheme is proven secure under the decisional bilinear Diffie-Hellman (DBDH) assumption, which is one of the most standard assumptions in bilinear groups. Compared to the non-monotonic KP-ABE scheme from the same assumption by Ostrovsky et al. (ACM-CCS'07), our scheme achieves more compact parameters. The master public key and the ciphertext size is about the half that of their scheme.
\item Our third scheme is the first non-monotonic KP-ABE scheme that can deal with unbounded size of set and access policies. That is, there is no restriction on the size of attribute sets and the number of allowed repetition of the same attributes which appear in an access policy. The master public key of our scheme is very compact: it consists of only constant number of group elements. \item Our fourth scheme is the first non-monotonic CP-ABE scheme that can deal with unbounded size of set and access policies. The master public key of the scheme consists of only constant number of group elements. \end{itemize} We construct our KP-ABE schemes in a modular manner. We first introduce special type of predicate encryption that we call two-mode identity based broadcast encryption (TIBBE). Then, we show that any TIBBE scheme that satisfies certain condition can be generically converted into non-monotonic KP-ABE scheme. Finally, we construct efficient TIBBE schemes and apply this conversion to obtain the above new non-monotonic KP-ABE schemes.
Category / Keywords: public-key cryptography / Original Publication (with major differences): IACR-PKC-2014 Date: received 6 Mar 2014 Contact author: yamada-shota at aist go jp Available format(s): PDF | BibTeX Citation Note: This is the full version of our paper in PKC2014. Version: 20140307:081722 (All versions of this report) Short URL: ia.cr/2014/181 Discussion forum: Show discussion | Start new discussion