[cs-talks] PhD Thesis Defense, Omer Paneth, Wednesday September 28, 2016 at 10:00 Hariri Institute for Computing Seminar Room MCS 180

Streubel, Jennifer jenn4 at bu.edu
Mon Sep 26 14:07:29 EDT 2016

PhD Thesis Defense
Program Obfuscation: Outside the Black Box
Omer Paneth
Wednesday, September 28, 10am.
Hariri Institute for Computing Seminar room MCS 180, 111 Cummington Mall
Code is said to be obfuscated if it is intentionally difficult for humans to understand. Obfuscation is often used to conceal sensitive implementation details such as proprietary algorithms or licensing mechanisms.

A general-purpose obfuscator is a compiler that obfuscates arbitrary code (in some particular language) without altering the code's functionality.  Ideally, the obfuscated code would hide any information about the original code that cannot be obtained by simply executing it.

The potential applications of general-purpose obfuscators extend beyond software protection. For example, in computational complexity theory, obfuscation is used to establish the intractability of a range of computational problems. Obfuscation is also a powerful tool in cryptography, enabling a variety of advanced applications.

The possibility of general-purpose obfuscation was put into question by Barak et al. [CRYPTO 01], who proved that such obfuscation cannot have ideal security. Nevertheless, they leave open the possibility of obfuscation with weaker security properties, which may be sufficient for many applications. Recently, Garg et al. [FOCS 13] suggested a candidate construction for general-purpose obfuscation conjectured to satisfy these security properties.

In this thesis we study the feasibility and applicability of different notions of secure obfuscation.

In terms of applicability, we prove that finding a Nash equilibrium of a game is intractable, based on a weak notion of obfuscation known as indistinguishability obfuscation.

In terms of feasibility, we focus on a variant of the Garg at el. obfuscator that is based on a recent construction of cryptographic multilinear maps [Garg et al. EUROCRYPT 13]. We reduce the security of the obfuscator to that of the underlying multilinear maps. Our first reduction considers obfuscation and multilinear maps with ideal security.

We then study a useful strengthening of indistinguishability obfuscation known as virtual-grey-box obfuscation. We identify security properties of multilinear maps that are necessary and sufficient for this notion.

Finally, we explore the possibility of basing obfuscation on weaker primitives. We show that obfuscation is impossible even based on ideal random oracles.
Examining Committee:

First reader: Prof. Ran Canetti
Second reader: Prof. Shafi Goldwasser (MIT)
Third reader: Prof. Leonid Reyzin
Committee chair: Prof. Steve Homer
Additional committee member: Prof. Vinod Vaikuntanathan (MIT)

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