An Efficient Method for Localization of Magnetic Field Sources That Produce High-Frequency Side-Channel Emanations

Presented is a new, low-cost system for locating the strongest sources of high-frequency EM side-channel emanations on PCBs. These sources indicate the best locations to monitor or mitigate the leakage. The challenges inherent in both side-channel and high-frequency measurements are addressed through careful design of the measurement and localization system. The system is time efficient, requiring only measurements taken around the edge of the device. Instead of testing specific cryptographic programs, this system focuses on identifying and then measuring the side-channel sources of the basic instructions that are commonly used by a multitude of programs on the device. The accuracy of the measurement setup was verified by comparing measurements with simulated results. The setup was then used to locate the instruction-dependent sources at 1 GHz on an field-programable gate array (FPGA) development board and an Internet-of-Things device. The 1 GHz sources are compared to previously identified sources on the same devices taken at significantly lower frequencies. The results demonstrate that the sources of the EM side channel can vary not only with the executed instruction, but also with the frequency of the side-channel signal.