Computing with obfuscated data in arbitrary logic circuits via noise insertion and cancellation

Abstract

In secure computing, sensitive data must be kept private by protecting it from being obtained by an attacker. Existing techniques for computing with encrypted data are either prohibitively expensive (e.g., fully homomorphic encryption) or only work for special cases. (e.g., only for linear circuits). This paper presents a lightweight methodology for computing with noise-obfuscated data by carefully selecting internal locations for noise cancellation in arbitrary logic circuits. Noise is inserted in the data before computation and then partially cancelled during the computation and fully cancelled at the outputs. While the proposed methodology does not provide the level of strong encryption that fully homomorphic encryption would provide, it has the advantage of being lightweight, easy to implement, and can be deployed with relatively minimal performance impact. A key idea in the proposed approach is to reduce the complexity of the noise cancellation logic by carefully selecting internal locations to do local noise canceling. This is done in a way that prevents more than one input per gate from propagating noise thereby avoiding the complexity that arises from reconvergent noise propagation paths. One important application of the proposed scheme is for protecting data inside a computing unit obtained from a third party IP provider where a hidden backdoor access mechanism or hardware Trojan could be maliciously inserted. Experimental results show that noise can be propagated to outputs with overheads ranging from (13%–56%).