Exploiting Multiple Scattering Materials and Techniques for Data Encryption and Storage

Securing sensitive information such as passwords and biometric data, as well as ensuring real-time identification and validation, is of paramount importance across various sectors, including banking and homeland security. Traditional holography has leveraged the hologram's dependence on illumination as an encryption key; and recent advancements—such as using orbital angular momentum (OAM), space light modulators (SLMs), and programmable metasurfaces—have expanded the key space and enhanced security. Additionally, employing complex, multiple scattering media has become a practical strategy for creating resilient ciphertexts. This method scrambles information-carrying waveforms via intricate, multipath channels, making decryption difficult without detailed knowledge of the medium or decryption models. Current methods that utilize media with complex scattering responses that blend the propagated signal are susceptible to eavesdropping by various interceptive attacks. Some existing methods also use machine-learning-based computational techniques for encryption, increasing the computational burden and requiring additional steps. Moreover, storing the algorithm and data on a server makes them vulnerable to hacker attacks. Herein, we introduce several techniques and algorithms to improve the functionality of multiple-scattering-based approaches for image and data encryption. We explore the use of dual scattering media in the encryption and decryption process, where the information is embedded in the differential signal corresponding to the two media. The utilized scattering media, which we refer to as keys, are random distributions of clusters of nanoscatterers, such as dielectric and plasmonic nanoparticles or nanoantennas in a background medium, with each key having a unique distribution of scatterers. Nevertheless, we explore potential candidates for use as scattering media, including novel metamaterials. We analyze the security benefits they offer and compare the performance of these different materials. We also discuss the advantages of using the differential sensing technique over previously utilized single scattering medium encryption methods and its resistance to brute-force interceptor attempts. Furthermore, we introduce another method where, in the case of using the correct keys, the output image becomes null or of low amplitude, which can be used for verification and barcode storage applications. We also present our simulation platform, which enables the calculation of the scattered field after it passes through a scattering material that may consist of thousands of scatterers. In contrast to earlier works that emphasized analog encryption followed by digital decryption, our approach highlights the complementary method of conducting encryption either analogically or digitally, paired with real-time analog decryption using appropriate scattering media. Finally, our proposed innovations provide a robust framework for real-time secure information processing.