A general and efficient obfuscation for programs with tamper-proof hardware

Abstract

Obfuscating programs is a fascinating area of cryptography. The known general method of obfuscating programs with tamper-proof hardware is to first transform a program P to the corresponding ensemble of circuits and then apply the known obfuscation for circuits, e.g. the one by Goyal et al. in TCC'10, to obfuscate some circuit in the ensemble. We think there may exist two shortcomings in this method. One is the size of the obfuscated circuit is polynomial in P's running-time instead of P's length. Another one is that the obfuscated circuit can only be run on inputs of fixed length instead of inputs of any length. In this paper we propose a general and efficient obfuscation for programs rather than circuits with tamper-proof hardware. The size of our obfuscated program for P is polynomial in P's length and the program can by run on an arbitrary polynomially long input. © 2011 Springer-Verlag Berlin Heidelberg.