Homomorphic Indistinguishability Obfuscation and its Applications
Kaartik Bhushan
Abstract:
The goal of code obfuscation is to compile programs such that the compiled version preserves functionality, but is "maximally unintelligible." The most standard notion of obfuscation in the literature is called indistinguishability obfuscation (or iO for short). In this work, we propose the notion of homomorphic indistinguishability obfuscation (HiO) and present a construction based on iO and one-way functions. An HiO scheme allows us to convert an obfuscation of circuit C to an obfuscation of C'o C, where o denotes composition, and this can be performed obliviously (that is, without knowing the circuit C). A naive solution would be to obfuscate C'o iO(C). However, if we do this for k hops, then the size of the final obfuscation is exponential in k. HiO ensures that the size of the final obfuscation remains polynomial after repeated compositions. As an application, we show how to build function-hiding hierarchical multi-input functional encryption and homomorphic witness encryption using HiO.
Bio:
Kaartik is a fifth year PhD student working under the guidance of Prof. Manoj Prabhakaran at IIT Bombay, India. Before starting his PhD, he completed his undergraduate degree in Computer Science and Engineering from IIT Kanpur, India. His main interests are in the field of program obfuscation and functional encryption. He has also worked on problems related to information-theoretic multi-party computation, foundational concepts and complexity theory. He has been awarded prestigious scholarships like KVPY and PMRF.