Physically-Guided Optical Inversion Enable Non-Contact Side-Channel Attack on Isolated Screens

arXiv cs.CV / 4/16/2026

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Key Points

  • The paper proposes a physically-guided optical side-channel attack that can exfiltrate electronic screen content without direct contact by projecting and inverting optical signals.
  • It identifies two key technical instabilities—near-singular projection mappings that break Hadamard stability and light-transport compression that removes global semantic cues—making naive inversion highly sensitive and ambiguous.
  • The authors introduce IR4Net, which combines a physically regularized irradiance approximation (embedding the radiative transfer equation into a learnable optimizer) with cross-scale contour-to-detail reconstruction to reduce noise propagation.
  • An irreversibility-constrained semantic reprojection module is used to restore lost global structure by mapping context to semantics.
  • Experiments across four scene categories show IR4Net achieving higher reconstruction fidelity than competing neural methods and improved robustness to illumination perturbations.

Abstract

Noncontact exfiltration of electronic screen content poses a security challenge, with side-channel incursions as the principal vector. We introduce an optical projection side-channel paradigm that confronts two core instabilities: (i) the near-singular Jacobian spectrum of projection mapping breaches Hadamard stability, rendering inversion hypersensitive to perturbations; (ii) irreversible compression in light transport obliterates global semantic cues, magnifying reconstruction ambiguity. Exploiting passive speckle patterns formed by diffuse reflection, our Irradiance Robust Radiometric Inversion Network (IR4Net) fuses a Physically Regularized Irradiance Approximation (PRIrr-Approximation), which embeds the radiative transfer equation in a learnable optimizer, with a contour-to-detail cross-scale reconstruction mechanism that arrests noise propagation. Moreover, an Irreversibility Constrained Semantic Reprojection (ICSR) module reinstates lost global structure through context-driven semantic mapping. Evaluated across four scene categories, IR4Net achieves fidelity beyond competing neural approaches while retaining resilience to illumination perturbations.