IACR News item: 27 February 2015
Prabhanjan Ananth, Abhishek Jain
ePrint ReportIn this work, we make progress in this direction by presenting a reduction from iO to a natural form of public-key functional encryption (FE). Specifically, we construct iO for general
functions from any sub-exponentially secure, single-key compact FE scheme for NC1 that achieves selective, indistinguishability security against sub-exponential time adversaries. Further, the FE scheme should be compact, namely, the running time of the encryption algorithm must only be a polynomial in the security parameter and the input message length and not depend on the function description size or its output length.
We achieve this result by developing a novel arity amplification technique to transform FE for single-ary functions into FE for multi-ary functions (aka multi-input FE). Instantiating our approach with known, non-compact FE schemes, we obtain the first constructions of multi-input FE for constant-ary functions based on standard assumptions.
Finally, as a result of independent interest, we construct a compact FE scheme from randomized encodings for Turing machines and learning with errors assumption.
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