International Association for Cryptologic Research

International Association
for Cryptologic Research

IACR News item: 09 November 2015

Prabhanjan Ananth, Abhishek Jain, Amit Sahai
ePrint Report ePrint Report
In this work, we introduce patchable obfuscation: our notion

adapts the notion of indistinguishability obfuscation (iO) to a very general setting where

obfuscated software evolves over time. We model this broadly by considering

software patches P as arbitrary Turing Machines that take as input the description of a

Turing Machine M, and output a new Turing Machine description M\' = P(M).

Thus, a short patch P can cause changes everywhere in the description of M and

can even cause the description length of the machine to increase by an arbitrary polynomial amount.

We further consider the setting where a patch is applied not just to a single

machine M, but to an unbounded set of machines (M_1, \\dots, M_t) to

yield (P(M_1), \\dots, P(M_t). We call this multi-program patchable obfuscation.

We consider both patchable obfuscation and multi-program patchable obfuscation

in a setting where there are an unbounded number of patches that can be adaptively

chosen by an adversary.

We show that sub-exponentially secure iO for circuits and sub-exponentially secure one-way functions imply patchable obfuscation; and we show that

sub-exponentially secure iO for circuits, sub-exponentially secure one-way functions,

and sub-exponentially secure DDH imply multi-program patchable obfuscation.

Finally, we exhibit some simple applications

of multi-program patchable obfuscation, to demonstrate how these concepts

can be applied.

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