IACR News item: 14 October 2015
Sanjam Garg, Omkant Pandey
ePrint ReportWe initiate a thorough investigation of {\\em incremental program obfuscation}. We show that the strong simulation-based notions of program obfuscation, such as ``virtual black-box\'\' and ``virtual grey-box\'\' obfuscation, cannot be incremental even for very simple functions such as point functions. We then turn to the indistinguishability-based notions, and present two security definitions of varying strength. To understand the overall strength of our definitions, we formulate the notion of {\\em incremental best-possible obfuscation} and show that it is equivalent to our (stronger) indistinguishability-based notion.
Finally, we present constructions for incremental program obfuscation satisfying both our security notions. We first give a construction achieving the weaker security notion based on the existence of general purpose indistinguishability obfuscation. Next, we present a generic transformation using {\\em oblivious RAM} to amplify security from weaker to stronger, while maintaining the incrementality property.
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