Indistinguishability Obfuscation for All Circuits from Secret-Key Functional Encryption

We show that indistinguishability obfuscation (IO) for all circuits can be constructed solely from secret-key functional encryption (SKFE). In the construction, SKFE need to be able to issue a-priori unbounded number of functional keys, that is, collusion-resistant. Our strategy is to replace public-key functional encryption (PKFE) in the construction of IO proposed by Bitansky and Vaikuntanathan (FOCS 2015) with puncturable SKFE. Bitansky and Vaikuntanathan introduced the notion of puncturable SKFE and observed that the strategy works. However, it has not been clear whether we can construct puncturable SKFE without assuming PKFE. In particular, it has not been known whether puncturable SKFE is constructed from ordinary SKFE. In this work, we show that a relaxed variant of puncturable SKFE can be constructed from collusion-resistant SKFE. Moreover, we show that the relaxed variant of puncturable SKFE is sufficient for constructing IO

The Birth of Cryptographic Obfuscation -- A Survey

The first candidate indistinguishability obfuscator (iO) of Garg et al. (FOCS 2013) changed the previously pessimistic attitude towards general-purpose cryptographic obfuscation. The potential realizability of such a powerful tool motivated a plethora of applications, including solutions for long-standing open problems, from almost all areas of cryptography. At the same time, the question of whether iO is realizable under standard assumptions is still open. In this work, we review the rapid development of candidate constructions and organize the results of the first four years since the breakthrough. Our goal is to give a bird\u27s-eye view of the infancy of cryptographic obfuscation, providing insight into the most important ideas and techniques