Applicability of Indistinguishability Obfuscation Seminar report for Research Seminar in Cryptography

The intuitive meaning of obfuscation is taking a program and turning it into a program with the same functionality but somehow unintelligible structure. There have been practical approaches at obfuscating computer programs, but until 2001 [BGI01] there was not much theory in this field. Especially, it was not well defined what is meant by obfuscation. The main step of specifying the meaning of obfuscation would be to precisely define this unintelligibility. In the strongest sense we would like to specify that nothing is leaked about the program except the respective input and output behaviour. This has been formalised as virtual black-box (VBB) obfuscation and deemed impossible [BGI01, BGI12]. The next best currently known approach for defining obfuscation is indistinguishability obfuscation. The main benefit is that we know that indistinguishability obfuscation is achievable for all circuits [GGH13]. On the other hand, indistinguishability obfuscation only guarantees that the two programs with the same functionality are indistinguishable when obfuscated. The aim of this work is to introduce the topic of indistinguishability obfuscation by exploring the usefulness of this concept. The level on which the properties and details of different proposed schemes are described in this paper varies a lot. In some cases this paper also tries to give an overview of how indistinguishability obfuscation is used in the proposed applications. Especially, the aim is to outline the most common or more easily understandable approaches. However, in many cases this paper serves as a reference pointing to the ideas rather than discussing the nature of many quite technical constructions. In addition, many cryptographic primitives or ideas are not explicitly defined. The main hope is that every reader would find an area of their interest and see how obfuscation has been applied to advance this field. In the following, Sec 2 defines what we mean by indistinguishability obfuscation and discusses what is provided by this concept. The second half of the paper in Sec 3 lists schemes where obfuscation has been used. The described results include both practical