On the Limits of Point Function Obfuscation

The authors study the problem of circuit obfuscation, i.e., transforming the circuit in a way that hides everything except its input-output behavior. Barak et al. showed that a universal obfuscator that obfuscates every circuit class cannot exist, leaving open the possibility of special-purpose obfuscators. Known positive results for obfuscation are limited to point functions (boolean functions that return 1 on exactly one input) and simple extensions thereof in the random oracle model, i.e., assuming black-box access to a true random function. It was also shown by Wee how to instantiate random oracles so as to achieve a slightly weaker form of point function obfuscation.