The Impossibility of Obfuscation with Auxiliary Input or a Universal Simulator

Bitansky, Nir; Canetti, Ran; Cohn, Henry; Goldwasser, Shafi; Kalai, Yael Tauman; Paneth, Omer; Rosen, Alon

doi:10.1007/978-3-662-44381-1_5

Cited by 33 publications

(6 citation statements)

References 20 publications

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“…We also know that no pseudorandom function family can be VBB obfuscated with respect to auxiliary inputs [12,37]. However, these results do not rule out the possibility that there exist pseudorandom functions whose obfuscated version is correlation intractable.…”

Section: Obfuscated Pseudorandom Functionsmentioning

confidence: 96%

On the Correlation Intractability of Obfuscated Pseudorandom Functions

Canetti

Chen

Reyzin

2015

Theory of Cryptography

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A family of hash functions is called "correlation intractable" if it is hard to find, given a random function in the family, an inputoutput pair that satisfies any "sparse" relation, namely any relation that is hard to satisfy for truly random functions. Indeed, correlation intractability is a strong and natural random-oracle-like property. However, it was widely considered unobtainable. In fact for some parameter settings, unobtainability has been demonstrated [26]. We construct a correlation intractable function ensemble that withstands all relations with a priori bounded polynomial complexity. We assume the existence of sub-exponentially secure indistinguishability obfuscators, puncturable pseudorandom functions, and input-hiding obfuscators for evasive circuits. The existence of the latter is implied by Virtual-Grey-Box obfuscation for evasive circuits [13].

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Section: Obfuscated Pseudorandom Functionsmentioning

confidence: 96%

On the Correlation Intractability of Obfuscated Pseudorandom Functions

Canetti

Chen

Reyzin

2015

Theory of Cryptography

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“…In this way, an efficient program that computes a property of the function can be constructed as D(P ′ f (x)) → {0, 1}, but it cannot be efficiently constructed from oracle access. Goldwasser et al [89] and Bitansky et al [90] further showed that some encryption programs cannot be obfuscated with VBBP when auxiliary inputs are available.…”

Section: ) Virtual Black-box Property (Vbbp)mentioning

confidence: 99%

On Secure and Usable Program Obfuscation: A Survey

Xu¹,

Zhou²,

Kang³

et al. 2017

Preprint

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Program obfuscation is a widely employed approach for software intellectual property protection. However, general obfuscation methods (e.g., lexical obfuscation, control obfuscation) implemented in mainstream obfuscation tools are heuristic and have little security guarantee. Recently in 2013, Garg et al. have achieved a breakthrough in secure program obfuscation with a graded encoding mechanism and they have shown that it can fulfill a compelling security property, i.e., indistinguishability. Nevertheless, the mechanism incurs too much overhead for practical usage. Besides, it focuses on obfuscating computation models (e.g., circuits) rather than real codes. In this paper, we aim to explore secure and usable obfuscation approaches from the literature. Our main finding is that currently we still have no such approaches made secure and usable. The main reason is we do not have adequate evaluation metrics concerning both security and performance. On one hand, existing code-oriented obfuscation approaches generally evaluate the increased obscurity rather than security guarantee. On the other hand, the performance requirement for model-oriented obfuscation approaches is too weak to develop practical program obfuscation solutions.

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“…Sahai and Waters suggested that the applications were so wide-ranging that indistinguishability obfuscation might become a "'central hub' for cryptography" [35]. These two breakthroughs were followed by a flurry of new activity in the area, including several new proposals and applications [8,11,12,13,21,29].…”

Section: Classical Obfuscationmentioning

confidence: 99%

On Quantum Obfuscation

Alagic¹,

Fefferman²

2016

Preprint

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Encryption of data is fundamental to secure communication in the modern world. Beyond encryption of data lies obfuscation, i.e., encryption of functionality. It is well-known that the most powerful means of obfuscating classical programs, so-called "black-box obfuscation," is provably impossible [6]. For years since, obfuscation was believed to always be either impossible or useless, depending on the particulars of its formal definition. However, several recent results have yielded candidate schemes that satisfy a definition weaker than black-box, and yet still have numerous applications.In this work, we initialize the rigorous study of obfuscating programs via quantum-mechanical means. We define notions of quantum obfuscation which encompass several natural variants. The input to the obfuscator can describe classical or quantum functionality, and the output can be a circuit description or a quantum state. The obfuscator can also satisfy one of a number of obfuscation conditions: black-box, information-theoretic black-box, indistinguishability, and best-possible; the last two conditions come in three variants: perfect, statistical, and computational. We discuss a number of applications, including CPA-secure quantum encryption, quantum fully-homomorphic encryption, and public-key quantum money. We then prove several impossibility results, extending a number of foundational papers on classical obfuscation to the quantum setting. We prove that quantum black-box obfuscation is impossible in a setting where adversaries can possess more than one output of the obfuscator (possibly even on the same input.) In particular, generic transformation of quantum circuits into black-box-obfuscated quantum circuits is impossible. We also show that statistical indistinguishability obfuscation is impossible, up to an unlikely complexity-theoretic collapse. Our proofs involve a new tool: chosen-ciphertext-secure encryption of quantum data, which was recently shown to be possible provided that quantum-secure one-way functions exist [5].We emphasize that our results leave open one intriguing possibility: black-box obfuscation of classical or quantum circuits into a single, uncloneable quantum state. This indicates that, in spite of our results, quantum obfuscation may be significantly more powerful than its classical counterpart.

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The Impossibility of Obfuscation with Auxiliary Input or a Universal Simulator

Cited by 33 publications

References 20 publications

On the Correlation Intractability of Obfuscated Pseudorandom Functions

On the Correlation Intractability of Obfuscated Pseudorandom Functions

On Secure and Usable Program Obfuscation: A Survey

On Quantum Obfuscation

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