International Association
for Cryptologic Research

Security and safety critical devices must undergo penetration testing including Side-Channel Attacks (SCA) before certification.

SCA are powerful and easy to mount but often need huge computation power, especially in the presence of countermeasures.

Few efforts have been done to reduce the computation complexity of SCA by selecting a small subset of points where leakage prevails.

In this paper, we propose a method to detect relevant leakage points in side-channel traces.

The method is based on Normalized Inter-Class Variance (NICV).

A key advantage of NICV over state-of-the-art is that NICV does neither need a clone device nor the knowledge of secret parameters of the crypto-system.

NICV has a low computation requirement and it detects leakage using public information like input plaintexts or output ciphertexts only.

It is shown that NICV can be related to Pearson correlation and signal to noise ratio (SNR) which are standard metrics.

NICV can be used to theoretically compute the minimum number of traces required to attack an implementation.

A theoretical rationale of NICV with some practical application on real crypto-systems are provided to support our claims.