As part of its mission, DTRA has been supporting the development of tamper-indicating seals. Tamper-indicating seals have been around for millennia, from ancient seals using wax and a signet-ring, to modern low-tech tamper-indicating adhesives and high-tech electronic devices. In all cases these seals seek to provide a mechanism by which to provide irrefutable proof of whether tampering has occurred or not.
The traditional functionality of tamper-indicating seals has been to record evidence of tampering occurring (e.g., deformed or ripped seal, electronic recording, etc.). This method is simple to implement, but is vulnerable to cloning attacks in which the seal is removed and replaced with a duplicate which contains no evidence of tampering.
An alternative to the evidentiary approach is to use an “anti-evidence” method in which the seal stores evidence corresponding to “no tampering has occurred,” which is destroyed if the seal is tampered with. The ideal implementation of the anti-evidence approach is a system called a physically unclonable function (PUF).
ASL developed an authentication method based on Wavefront-Shaped Optical Responses. For these optically physically unclonable functions (O-PUF) surface markers, ASL uses a nanocomposite consisting of a transparent polymer with dispersed nanoparticles (NP). Polymers are chosen as the host material as their properties are widely tunable based on composition and are easily applied to a variety of surfaces.
The reflection geometry optical authentication system is operational and has been tested with various nanocomposites. Using this system, ASL has demonstrated the ability to detect various types of tampering (e.g., mechanical, thermal, chemical) on surface markers to a high degree of accuracy, see movies below.
References:
1. Hergen Eilers, Benjamin R. Anderson, Ray Gunawidjaja, and Patrick Price, “Spatial-Light-Modulator-Based Signatures of Intrinsic and Extrinsic Scattering Surface Markers for Secure Authentication,” US Patent US9762565B2 (2017).
2.Benjamin Anderson, Ray, Gunawidjaja, and Hergen Eilers, “Random Lasing and reversible Photodegradationin Disperse Orange 11 Dye-doped PMMA with Dispersed ZrO2Nanopaticles,” J. Opt. accepted for publication (2015).
3.Benjamin Anderson, Ray, Gunawidjaja, and Hergen Eilers, “Stability of optimal-wavefront-sample coupling under sample translation and rotation,” Phys. Rev. A 91, 063802 (2015).
4.Benjamin Anderson, Ray, Gunawidjaja, and Hergen Eilers, “Photodegradation and Self-Healing in a Rhodamine 6G Dye and Y2O3Nanoparticle-Doped Polyurethane Random Laser,” Appl. Phys. B. 120(1) 1-12 (2015).
5.Benjamin Anderson, Patrick Price, Ray Gunawidjaja, and Hergen Eilers, “A Microgenetic Optimization Algorithm for Focusing Light Through Opaque Media,” Appl. Opt. 54, 1485 (2015). Highlighted in Spotlight on Optics.
6.Benjamin Anderson, Ray, Gunawidjaja, and Hergen Eilers, “Self-healing organic-dye-based random lasers,” Opt. Lett. 40, 577 (2015).
7.Benjamin Anderson, Ray, Gunawidjaja, and Hergen Eilers, “The Effect of Experimental Parameters on Optimal Transmission of Light Through Opaque Media,” Phys. Rev. A 90, 053826 (2014).
8.Benjamin Anderson, Ray, Gunawidjaja, and Hergen Eilers, “Low-Threshold and Narrow Linewidth Random Lasing in Rhodamine 6G Dye-Doped Polyurethane with Dispersed ZrO₂ Nanoparticles,” J. Opt. Soc. Am. B, 31 (10), pp 2363-2370 (2014).
