A Novel Method for Power Analysis Based on Combinational Logic in Block Cipher Circuit

In this paper, we propose a method that builds power model template according to input transitions of combinatorial logic circuit. By computing its correlation with the overall power consumption of a cryptographic circuit, we are able to recover the secret key. Several simulation-based experiments have been conducted, which verifies the feasibility of our method and shows that the combinatorial logic is also faced with the problem of information leakage in power analysis cases. Compared with DPA (Differential power analysis) and CPA (Correlation power analysis), our attack is fairly effective against the cryptographic circuits whose protection is only implemented on the register parts of the sequential circuit. In addition, a few topics for further research, as well as the advices for more precise power model and countermeasures, are presented at the end of the paper.