# Near-Field Microwave Sensing for Chip-Level Tamper Detection

## TL;DR

A new contactless method using microwave sensors detects tampering in microchips without needing to activate malicious circuits.

## Contribution

Introduces a non-invasive tamper detection method using CSRRs to monitor impedance changes in chip power networks.

## Key findings

- CSRR sensors detect impedance changes in chip power delivery networks caused by tampering.
- The method successfully identifies tamper events on an FPGA without activating malicious circuits.
- Approach is scalable and does not require physical contact with the chip or PCB.

## Abstract

Stealthy chip-level tamper attacks, such as hardware Trojan insertions or security-critical circuit modifications, can threaten modern microelectronic systems’ security. While traditional inspection and side-channel methods offer potential for tamper detection, they may not reliably detect all forms of attacks and often face practical limitations in terms of scalability, accuracy, or applicability. This work introduces a non-invasive, contactless tamper detection method employing a complementary split-ring resonator (CSRR). CSRRs, which are typically deployed for non-destructive material characterization, can be placed on the surface of the chip’s package to detect subtle variations in the impedance of the chip’s power delivery network (PDN) caused by tampering. The changes in the PDN’s impedance profile perturb the local electric near field and consequently affect the sensor’s impedance. These changes manifest as measurable variations in the sensor’s scattering parameters. By monitoring these variations, our approach enables robust and cost-effective physical integrity verification requiring neither physical contact with the chips or printed circuit board (PCB) nor activation of the underlying malicious circuits. To validate our claims, we demonstrate the detection of various chip-level tamper events on an FPGA manufactured with 28 nm technology.