Advanced stochastic methods in side channel analysis on block ciphers in the presence of masking

Abstract

At CHES 2005 a new stochastic approach for differential side channel cryptanalysis on block ciphers was introduced and studied intensively. In the present paper we focus on a generalized variant that can handle arbitrary masking techniques. Our approach combines engineer's intuition and expertise with precise stochastic methods and provides insight into the ‘nature’ of the leakage signal. In particular, this supports the design of secure cryptosystems constructively. The attacking efficiency of our approach is much better than that of DPA attacks. It is limited by the attacking efficiency of ’classical’ template attacks but profiling is (at least) by an order of magnitude more efficient.

Keywords

• side channel analysis
• masking
• stochastic approach
• multivariate statistics
• template attack