IEEE TRANSACTIONS ONNANOTECHNOLOGY, Volume 18, 2019 1079 Versatile Authentication Using an Identifier Based On Optical Variable Nanostructures Devarshi Patel , Hao Jiang , Jasbir Patel, and Bozena Kaminska Abstract—Counterfeit electronic devices are increasingly recog- nized as severe threats for the security of cyber-physical systems. To authenticate and verify original devices and manufacturers, an op- tical authentication identifier based on a pixelated nano-substrate and a versatile intensity control layer is introduced in this article. The pixelated nano-substrate is comprised of color pixels based on optical variable nanostructures whereas the intensity control layer is designed to activate or deactivate specific color pixels. A response image acquisition device based on angle-dependent optical diffraction is constructed to register the authentic identifiers and to detect fake identifiers. In the registration stage, the extracted data (color information) of the authentic identifier is stored as a reference on a secured server. In the authentication stage, the data are obtained from a detected identifier and compared to the reference using block-by-block calculations of inter-distances and intra-distances. Experimental results and analysis show that the proposed scheme can accomplish the authentication of the optical identifier with high reliability and robustness. Index Terms—Optical identifier, optical variable nanostructure, structural color, intensity control layer, authentication and verification. I. INTRODUCTION A RELIABLE authentication identifier (ID) is a crucial el- ement of security infrastructure that protects not only confidentiality but also value and reputation by serving as an anti-counterfeiting solution for any stand-alone systems or for one or more elements of any cyber-physical system (CPS). An authentication identifier can provide secure access to information or a system by verifying the authenticity of a user/device. The authentication systems can be categorized into three different methods as shown in Fig. 1(a). Knowledge-based authentication (KBA) is the simplest and prominent way of authentication. A password is one example of the most widely used KBAs. The password can be considered as a software-based ID as the control and storage of the key’s code are governed strictly by software. Since the key’s code (password) must be Manuscript received June 28, 2019; revised September 5, 2019; accepted September 17, 2019. Date of publication September 30, 2019; date of current version October 25, 2019. This work was supported in part by the NSERC Strategic Grant. The review of this paper was arranged by associate editor S. Samukawa. D. Patel, J. Patel, and B. Kaminska are with the Department of Engineering Science, Simon Fraser University, Burnaby, BC V5A1S6, Canada (e-mail: devarshi_patel@sfu.ca; jpatel@sfu.ca; kaminska@sfu.ca). H. Jiang was with the School of Engineering Science, Simon Fraser Uni- versity, Burnaby, BC V5A1S6, CANADA. He is now with the Department of Biomedical Engineering, Lawrence Technological University, Southfield, MI 48075 USA (e-mail: hja27@sfu.ca). Digital Object Identifier 10.1109/TNANO.2019.2943298 Fig. 1. Methods of authentication (a) and counterfeit avoidance (b). loaded into memory for access, it may be stolen through memory dumps and kernel attacks [1]. Physical ID uses hardware security modules to store and man- age access. Traditional IDs include inks, holograms, barcode stickers, and radio frequency identification device (RFID) tags and are commonly used for access control, passports, commer- cial transactions, by hospitals and healthcare, bank cards, etc. However, these IDs are easy to be duplicated or hacked. In comparison, authentication using biometric information is based on a unique and unclonable characteristic which is a much more robust approach to authenticate a device/person. As counterfeit approaches are becoming more advanced, the need for incorporating efficient and robust authentication identi- fier on electronic components is rising, too. Such authentication identifiers must be hard or even impossible to be duplicated by counterfeiters. In this paper, we introduce a new identifier based on the optical variable nanostructures that are designed and fabricated by the original processes. The identification algorithm allows on the recognition of the authentic identifier. The rest of the paper is organized as follows: related work is introduced in Section II; the proposed solution is described in Section III; the methodology is described in Section IV, and experimental results and analysis are provided in Section V. Discussion is carried out in Section VI. Finally, conclusions are drawn in Section VII. II. RELATED WORK Fig. 1(b) shows some of the counterfeit avoidance methods, which are broadly classified into two categories: chip ID and 1536-125X © 2019 IEEE. Personal use is permitted, but republication/redistribution requires IEEE permission. See http://www.ieee.org/publications_standards/publications/rights/index.html for more information.