IACR News item: 27 February 2015
Nuttapong Attrapadung, Shota Yamada
ePrint ReportIn this paper, we revisit the dual conversion of Attrapadung, and show that, somewhat surprisingly, the very same conversion indeed also works for broader classes of encodings, namely, computationally secure encodings. Consequently, we thus solve the above open problems as we obtain the first fully secure realizations of completely-unbounded CP-ABE and CP-ABE with short keys for Boolean formulae, via applying the conversion to previously proposed KP-ABE.
Moreover, we provide a generic conversion that converts ABE into its dual-policy variant. Dual-policy ABE (DP-ABE) conjunctively combines both KP-ABE and CP-ABE into one primitive, and hence can be useful in general-purpose applications. As for instantiations, we obtain the first realizations of fully secure DP-ABE for formulae, unbounded DP-ABE for formulae, and DP-ABE for regular languages. The latter two systems are the first to realize such functionalities, let alone are fully secure.
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