Methodology for complete decorrelation of power supply em side-channel signal and sensitive data

Resumen

Electro-magnetic (EM) side channel attacks have become a serious threat to security of Internet-of-Things (IoT) devices. Power supply generated by voltage regulators is one of the most common attack targets due to its strong EM emanations. In this brief we derive analytical conditions for complete theoretical decorrelation of the power supply EM side-channel signal and the sensitive data. The output of the power supply converter is modelled as amplitude modulation (AM) of the load signal by the converter capacitance that acts as a carrier. By applying Price theorem (Papoulis and Pillai, 2002), we obtain the exact theoretical conditions that converter capacitance needs to fulfil in order to prevent EM side-channel attacks. The conditions are further adapted for practical implementation. When the proposed methodology is applied to AES measured traces, the correlation coefficient between the leaked signal and the sensitive data is 0.05. Such low correlation indicates the proposed methodology is a promising candidate against the attacks that exploit AM signals to extract sensitive data, such as, TEMPEST and active EM attacks. Test Vector Leakage Assessment (TVLA) rho-test detects no leaky points, thereby confirming circuit protection against differential and correlation EM attacks as well.