Instantaneous Frequency Analysis

This paper investigated the use of instantaneous frequency (IF) instead of power amplitude and power spectrum in side-channel analysis. By opposition to the constant frequency used in Fourier Transform, instantaneous frequency reflects local phase differences and allows detecting frequency variations. These variations reflect the processed binary data and are hence cryptanalytically useful. IF exploits the fact that after higher power drops more time is required to restore power back to its nominal value. Whilst our experiments reveal IF does not bring specific benefits over usual power attacks when applied to unprotected designs, IF allows to obtain much better results in the presence of amplitude modification countermeasures.