Efficient obfuscation for CNF circuits and applications in cloud computing

Abstract

With the rapid development of cloud computing, amounts of new concerns for security have been suggested. Cryptographic protocols are useful tools to address the problem emerging in cloud computing. Among those protocols, program obfuscation gradually showed the exclusive advantages that it can provide for cloud computing. In this paper, we present a cloud signing scheme, which can outsource the signing rights of a client to a cloud server securely by applying obfuscation. To improve the efficiency of obfuscation, we construct an obfuscator for all polynomial-size CNF circuits, which has the potential to avoid matrix branching programs and multilinear maps. A new notion of homomorphic encoding schemes, whose functionality is weaker than that of graded encoding schemes, is defined to complete our construction. The obfuscator is proven to be virtual black-box secure in the idealized homomorphic encoding model.