MCA-Based Multi-Channel Fusion Attacks Against Cryptographic Implementations

Multi-channel fusion attacks (MCFAs) are a more effective kind of side-channel analysis approaches for evaluating the side-channel vulnerability of a cryptographic device as compared to side-channel attacks exploiting only monochannel leakage. However, research for MCFAs is insufficient to explore their greatest potential. Considering that multi-channel leakages are generated by the same crypto device and collected individually, the paper holds the opinion that there exists a linear combination of the multi-channel leakages or leakage features or attack results to launch a fusion attack with the highest performance. Correspondingly, this paper develops three optimal strategies of MCFAs on the basis of multiple correlation analysis (MCA). In addition, a new MCA-based leakage fusion metric applied for measuring whether or not to combine a channel with other channels for fusion attacks is constructed as well. The proposed metric can select the channels with similar noise levels for combination and reduce the possibility of negative influences on leakage fusion caused by high-noise channels. Effectiveness of the proposed optimal fusion attacks and the new fusion metric are verified by practical experiments in typical scenarios, respectively.