Multiplex Optical Unclonable Functions: Advances and Perspectives in Optics and Photonics for Hardware Security
Srinivas Gandla, Changgyun Moon, Jung Woo Leem, Jinsik Yoon, Hee Seong Yun, Min Seok Kim, Dongmin Kim, Sunjong Lee, Yao Yao, Dimitris Alexandropoulos, Young Min Song, Dong Ki Yoon, Wook Park, Young L. Kim, Sunkook Kim
With the accelerating expansion of connectivity, the need for advanced cyber-physical security technologies that bridge the digital and physical worlds is becoming more crucial than ever. Physically unclonable functions (PUFs) leveraging nanotechnologies and photonic technologies are emerging as practical and deployable hardware security solutions that go beyond software-based hardware security. Optics- and photonics-based PUFs (often referred to as optical PUFs) offer a range of characteristics beneficial to multiplex strategies that incorporate multilevel and multimodal approaches, based on their fundamental optical and photonic properties. PUFs are categorized as multilevel when multiple responses are generated from a single type of challenge, such as a light source or optical tool. In contrast, they are classified as multimodal when multiple responses are created from various types of challenges involving a combination of different light sources and optical tools. This review highlights recent advances and progress in integrating emerging materials, detection tools, authentication methods, imaging techniques, reconfigurability, and unclonability, which are essential for advancing next-generation multiplex PUFs. To facilitate real-world applications and to support deployment in real-world senarios, we also discuss existing limitations in multiplex optical PUFs and explore potential strategies to overcome such challenges, supporting our increasingly hyperconnected society.
With the accelerating expansion of connectivity, the need for advanced cyber-physical security technologies that bridge the digital and physical worlds is becoming more crucial than ever. Physically unclonable functions (PUFs) leveraging nanotechnologies and photonic technologies are emerging as practical and deployable hardware security solutions that go beyond software-based hardware security. Optics- and photonics-based PUFs (often referred to as optical PUFs) offer a range of characteristics beneficial to multiplex strategies that incorporate multilevel and multimodal approaches, based on their fundamental optical and photonic properties. PUFs are categorized as multilevel when multiple responses are generated from a single type of challenge, such as a light source or optical tool. In contrast, they are classified as multimodal when multiple responses are created from various types of challenges involving a combination of different light sources and optical tools. This review highlights recent advances and progress in integrating emerging materials, detection tools, authentication methods, imaging techniques, reconfigurability, and unclonability, which are essential for advancing next-generation multiplex PUFs. To facilitate real-world applications and to support deployment in real-world senarios, we also discuss existing limitations in multiplex optical PUFs and explore potential strategies to overcome such challenges, supporting our increasingly hyperconnected society.
Abstract A physical unclonable function (PUF) device leverages manufacturing randomness to generate a unique fingerprint for secure authentication, encryption, and counterfeit prevention. Optical PUFs (OPUFs) have gained prominence due to their strong security, light‐based challenge‐response mechanisms, and potential for quantum‐secure encryption. These devices have promising applications for hardware security, authentication, cryptographic key generation, and anti‐counterfeiting measures across multiple industries. This review enlightens the diverse material platforms used for OPUFs, ranging from fiber optics and liquid crystals to advanced semiconductor nanocrystals and plasmonic metasurfaces, each offering distinct optical characteristics that impact security strength. While no single material system dominates the field, hybrid and multi‐model approaches integrating low‐dimensional materials are being explored to enhance reliability and scalability. Finally, the challenges and future perspectives are outlined, including adaptive OPUFs architectures, utilizing artificial intelligence (AI) for challenge‐response generation, and their integration into quantum communication networks, highlighting how next‐generation semiconductor materials can further advance OPUFs technologies.
Physically unclonable functions (PUFs) have emerged as a promising hardware security primitive, and recent years have seen growing interest in realizing PUFs on photonic integrated circuits (PICs). We classify existing PIC-based PUFs into electrically configured and optically encoded designs. Notably, security properties remain insufficiently analyzed, with mathematical unclonability often assumed without supporting argument. To illustrate this issue, we introduce a modeling attack against the subclass of optically encoded PUFs that operate in a linear optical regime. We show that, for a representative simulated PUF construction, observing as few as 200 challenge-response pairs allows learning the challenge-response mapping. Under canonical modeling assumptions, linear optically encoded PUFs are therefore mathematically clonable, calling for a careful assessment of their suitability for authentication protocols that rely on mathematical unclonability.
Quantum dots (QDs) have garnered significant attention for their unique size-dependent optical and electronic properties, enabling their widespread use in applications ranging from high-efficiency photovoltaics and light-emitting diodes to biomedical imaging and quantum computing. Their tunable emission, high photo-stability, and ease of surface modification make them ideal candidates for precision nanotechnology applications. In this work, we explore a novel and rapidly emerging application of QDs in hardware security through the development of Quantum Dot-based Physical Unclonable Functions (QD-PUFs). Unlike conventional security paradigms, QD-PUFs leverage the intrinsic physical randomness of QD-based nanostructures to generate challenge-response pairs with superior uniqueness, reliability, and robustness. We review the integration of QDs into PUFs, beginning with their material properties and extending to entropy sources arising from synthesis and fabrication, surface and encapsulation effects. A comparative analysis of different readout mechanisms and related applications underscores the unique encoding capacity and security potential of QD-based systems. By demonstrating their feasibility for scalable, high-security applications, this study underscores the transformative impact of QDs in next-generation authentication and anti-counterfeiting technologies.
Quantum Physically Unclonable Functions (QPUFs) are emerging hardware primitives that harness inherent quantum principle to produce device-specific challenge–response behavior. By embedding quantum-mechanical "fingerprints" into devices, QPUFs can derive unique cryptographic keys and identities, yielding robust hardware roots of trust. This paper systematically reviews QPUF principles, architectures, and security properties, and explores their integration into next-generation networking paradigms with industrial demonstrations. We detail how QPUFs can enable secure device authentication, key generation across quantum communication links, 6G wireless, IoT/edge deployments emphasizing practical implementation strategies and system integration in future networks along with technical challenges. Through this comprehensive analysis, we highlight the transformative potential of QPUFs in delivering hardware-rooted, information-theoretic security for interconnected networks, and outline directions for further research.
Physical unclonable functions (PUFs), physical objects that are practically unclonable because of their andom and uncontrollable manufacturing variations, are becoming increasingly popular as security primitives and unique identifiers in a fully digitized world. One of the central PUF premises states that both friends and foes, both legitimate manufacturers and external attackers alike, cannot clone a PUF, producing two instances that are the same. Using the latest nanofabrication techniques, we show that this premise is not always met: We demonstrate the possibility of effective PUF duplication through sophisticated manufacturers by producing 63 copies of a non-trivial optical scattering structure which exhibit essentially the same scattering behavior. The remaining minuscule differences are close to or below noise levels, whence the duplicates have to be considered fully equivalent from a PUF perspective. The possibility for manufacturer-based optical PUF duplication has positive and negative consequences at the same time: While fully breaking the security of certain schemes, it enables new applications, too. For example, it facilitates unforgeable labels for valuable items; the first key-free group identification schemes over digital networks; or new types of encryption/decryption devices that do not contain secret keys.
Disordered photonic structures are promising materials for the realization of physical unclonable functions (PUF), physical objects that can overcome the limitations of conventional digital security methods and that enable cryptographic protocols immune against attacks by future quantum computers. One PUF limitation, so far, has been that their physical configuration is either fixed or can only be permanently modified, and hence allowing only one token per device. We show that it is possible to overcome this limitation by creating a reconfigurable structure made by light-transformable polymers, in which the physical structure of the unclonable function itself can be reversibly reconfigured. We term this novel concept Hyper PUF or HPUF in that it allows a large number of physical unclonable functions to co-exist simultaneously within one and the same device. The physical transformation of the structure is done all-optically in a reversible and spatially controlled fashion. Our novel technology provides a massive enhancement in security generating more complex keys containing a larger amount of information. At the same time, it allows for new applications, for example serving multiple clients on a single encryption device and the practical implementation of quantum secure authentication of data.