Cryptology ePrint Archive: Report 2014/666

Fully Secure Functional Encryption without Obfuscation

Sanjam Garg and Craig Gentry and Shai Halevi and Mark Zhandry

Abstract: Previously known functional encryption (FE) schemes for general circuits relied on indistinguishability obfuscation, which in turn either relies on an exponential number of assumptions (basically, one per circuit), or a polynomial set of assumptions, but with an exponential loss in the security reduction. Additionally these schemes are proved in an unrealistic selective security model, where the adversary is forced to specify its target before seeing the public parameters. For these constructions, full security can be obtained but at the cost of an exponential loss in the security reduction.

In this work, we overcome the above limitations and realize a fully secure functional encryption scheme without using indistinguishability obfuscation. Specifically the security of our scheme relies only on the polynomial hardness of simple assumptions on multilinear maps.

Category / Keywords: public-key cryptography / functional encryption, graded encodings, adaptive security,

Date: received 25 Aug 2014, last revised 11 Sep 2014

Contact author: mzhandry at stanford edu

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Version: 20140911:165417 (All versions of this report)

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