When Does Functional Encryption Imply Obfuscation?

12Citations
Citations of this article
21Readers
Mendeley users who have this article in their library.

This article is free to access.

Abstract

Realizing indistinguishablility obfuscation (IO) based on well understood computational assumptions is an important open problem. Recently, realizing functional encryption (FE) has emerged as a promising direction towards that goal. This is because: (1) compact single-key FE (where the functional secret-key is of length double the ciphertext length) is known to imply IO [Anath and Jain, CRYPTO 2015; Bitansky and Vaikuntanathan, FOCS 2015] and (2) several strong variants of single-key FE are known based on various standard computation assumptions. In this work, we study when FE can be used for obtaining IO. We show any single-key FE for function families with “short” enough outputs (specifically the output is less than ciphertext length by a value at least ω(n + κ), where n is the message length and κ is the security parameter) is insufficient for IO even when non-black-box use of the underlying FE is allowed to some degree. Namely, our impossibility result holds even if we are allowed to plant FE sub-routines as gates inside the circuits for which functional secret-keys are issued (which is exactly how the known FE to IO constructions work). Complementing our negative result, we show that our condition of “short” enough is almost tight. More specifically, we show that any compact single-key FE with functional secret-key output length strictly larger than ciphertext length is sufficient for IO. Furthermore, we show that non-black-box use of the underlying FE is necessary for such a construction, by ruling out any fully black-box construction of IO from FE even with arbitrary long output.

Cite

CITATION STYLE

APA

Garg, S., Mahmoody, M., & Mohammed, A. (2017). When Does Functional Encryption Imply Obfuscation? In Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics) (Vol. 10677 LNCS, pp. 82–115). Springer Verlag. https://doi.org/10.1007/978-3-319-70500-2_4

Register to see more suggestions

Mendeley helps you to discover research relevant for your work.

Already have an account?

Save time finding and organizing research with Mendeley

Sign up for free