Roadmap on optical security

Information security and authentication are important challenges facing society. Recent attacks by hackers on the databases of large commercial and financial companies have demonstrated that more research and development of advanced approaches are necessary to deny unauthorized access to critical data. Free space optical technology has been investigated by many researchers in information security, encryption, and authentication. The main motivation for using optics and photonics for information security is that optical waveforms possess many complex degrees of freedom such as amplitude, phase, polarization, large bandwidth, nonlinear transformations, quantum properties of photons, and multiplexing that can be combined in many ways to make information encryption more secure and more difficult to attack. This roadmap article presents an overview of the potential, recent advances, and challenges of optical security and encryption using free space optics. The roadmap on optical security is comprised of six categories that together include 16 short sections written by authors who have made relevant contributions in this field. The first category of this roadmap describes novel encryption approaches, including secure optical sensing which summarizes double random phase encryption applications and flaws [Yamaguchi], the digital holographic encryption in free space optical technique which describes encryption using multidimensional digital holography [Nomura], simultaneous encryption of multiple signals [Pérez-Cabré], asymmetric methods based on information truncation [Nishchal], and dynamic encryption of video sequences [Torroba]. Asymmetric and one-way cryptosystems are analyzed by Peng. The second category is on compression for encryption. In their respective contributions, Alfalou and Stern propose similar goals involving compressed data and compressive sensing encryption. The very important area of cryptanalysis is the topic of the third category with two sections: Sheridan reviews phase retrieval algorithms to perform different attacks, whereas Situ discusses nonlinear optical encryption techniques and the development of a rigorous optical information security theory. The fourth category with two contributions reports how encryption could be implemented at the nano- or micro-scale. Naruse discusses the use of nanostructures in security applications and Carnicer proposes encoding information in a tightly focused beam. In the fifth category, encryption based on ghost imaging using single-pixel detectors is also considered. In particular, the authors [Chen, Tajahuerce] emphasize the need for more specialized hardware and image processing algorithms. Finally, in the sixth category, Mosk and Javidi analyze in their corresponding papers how quantum imaging can benefit optical encryption systems. Sources that use few photons make encryption systems much more difficult to attack, providing a secure method for authentication.Centro de Investigaciones ÓpticasConsejo Nacional de Investigaciones Científicas y Técnica

Roadmap on optical security

Information security and authentication are important challenges facing our society. Recent attacks by hackers on the databases of large commercial and financial companies have demonstrated that more research and developments of advanced approaches are necessary to deny unauthorized access to critical data. Free space optical technology has been investigated by many researchers in information security, encryption, and authentication. The main motivation for using optics and photonics for information security is that optical waveforms possess many complex degrees of freedom such as amplitude, phase, polarization, large bandwidth, nonlinear transformations, quantum properties of photons, and multiplexing that can be combined in many ways to make the information encryption more secure and more difficult to attack. This roadmap article presents an overview of the potential, recent advances, and the challenges of optical security and encryption using free space optics. The roadmap on optical security is comprised of six categories that together include 16 short sections written by authors who have made relevant contributions in this field. The first category of this roadmap describes novel encryption approaches, including secure optical sensing which summarizes double random phase encryption applications and flaws [Yamaguchi], digital holographic encryption in free space optical technique which describes encryption using multidimensional digital holography [Nomura], simultaneous encryption of multiple signals [Pérez-Cabré], asymmetric methods based on information truncation [Nishchal], and dynamic encryption of video sequences [Torroba]. Asymmetric and one-way cryptosystems are analyzed by Peng. The second category is on compression for encryption. In their respective contributions, Alfalou and Stern propose similar goals involving compressed data and compressive sensing encryption. The very important area of cryptanalysis is the topic of the third category with two sections: Sheridan reviews phase retrieval algorithms to perform different attacks, whereas Situ discusses nonlinear optical encryption techniques and the development of a rigorous optical information security theory. The fourth category with two contributions reports how encryption could be implemented in the nano- or microscale. Naruse discusses the use of nanostructures in security applications and Carnicer proposes encoding information in a tightly focused beam. In the fifth category, encryption based on ghost imaging using single-pixel detectors is also considered. In particular, the authors [Chen, Tajahuerce] emphasize the need for more specialized hardware and image processing algorithms. Finally, in the sixth category, Mosk and Javidi analyze in their corresponding papers how quantum imaging can benefit optical encryption systems. Sources that use few photons make encryption systems much more difficult to attack, providing a secure method for authentication

Image encryption using binary polarization states of light beam

Abstract Optical image/data encryption techniques are mostly based on the manipulation of spatial distributions of light's amplitude, phase, and polarization. Information encoding with phase involves complex interferometric set-up and polarization encoding requires Stoke’s parameter measurement. Hence, they create difficulties in optical implementation. Considering the practical limitations, in this study, we demonstrate a method of single-shot intensity recording-based color image encryption by encoding the information in binary polarization states. The proposed method does not require Stoke parameter calculation. As a proof-of-concept, we demonstrated the technique with coherent and partially coherent light sources. Use of partially coherent light overcomes the speckle problem and makes the system cost-effective, useful for practical applications

Three-Dimensional Image Watermarking Using Fractional Fourier Transform

In this paper, we propose an optical image watermarking scheme using the fractional Fourier transform. A two-dimensional watermark is encrypted using a double random fractional order Fourier domain encoding technique. The encrypted image is watermarked into a three-dimensional intensity image reconstructed from a real in-line digital hologram. The watermark is recovered by applying the corresponding correct fractional orders and random phase masks. Results of computer simulation have been presented in support of the proposed watermarking scheme

Three-Dimensional Image Watermarking Using Fractional Fourier Transform

In this paper, we propose an optical image watermarking scheme using the fractional Fourier transform. A two-dimensional watermark is encrypted using a double random fractional order Fourier domain encoding technique. The encrypted image is watermarked into a three-dimensional intensity image reconstructed from a real in-line digital hologram. The watermark is recovered by applying the corresponding correct fractional orders and random phase masks. Results of computer simulation have been presented in support of the proposed watermarking scheme

Flexible optical encryption with multiple users and multiple security levels

We present a basic optical encryption architecture that admits several cryptography applications based on multiplexing. Users can decrypt different private images from the same encrypted image, a superuser can have a key that decrypts all encrypted images, and multiplexed images can be encrypted with different levels of security. This system is presented in the context of a general framework of optical encryption application development. We illustrate with a real-world three-dimensional scene, captured with digital holography, and encrypted using the fractional Fourier transform, where different users have access to different three-dimensional objects in the scene

Digital Fresnel Hologram Watermarking

We present a method of digital hologram watermarking using a Fresnel hologram of a real-world 3D object and the fractional Fourier transform. A watermark is encrypted using double random phase fractional Fourier domain encoding technique and then encoded into the digital hologram. The hologram is watermarked in a plane at some known distance from the object so that even if a new hologram is generated from the original hologram the watermark can always be traced by propagating the new hologram back to the object and then onto the watermark plane. The watermark is retrieved successfully using the correct encryption parameters. We consider both numerical (full complex field) and optoelectronic (phase-only) reconstruction methods. We obtain the watermark from different windows of the hologram corresponding to different reconstruction perspectives

Design parameters of hybrid correlator

844-851In this paper, the design issues of a hybrid correlator are discussed. The architecture of the hybrid correlator is similar to the conventional 4-f correlator, with a difference that the first Fourier transformation, filter synthesis and their multiplica-tion are done digitally using a digital signal-processing unit. The input to the correlator is the scene/target captured either through a CCD camera or thermal imager. Wavelet-modified maximum average correlation height filter is used for catering the need of in-plane rotation, out-of-plane rotation and scale invariant target recognition. The product function is displayed over a high-speed spatial light modulator, which when illuminated with a laser light results correlation outputs due to optical Fourier transformation. A chirp function is employed with the filters that helps to capture the desired autocorrelation peak discarding the dc and one of the undesired autocorrelation peaks. The space-bandwidth of the processor and focal length of the required lens are discussed. The requirement of zero padding of the product function is also discussed. Simulation and experimental results are presented

Complex data mapping on a binary ferroelectric liquid crystal electrically addressed spatial light modulator for target recognition

647-653For displaying a complex valued function onto a binary amplitude-only or phase-only spatial light modulator, an encoding technique is required. In this paper, we implement an encoding scheme proposed by Davis et al. [Appl Opt, 42 (2003) 2003] for optical processing the complex product function in the hybrid digital-optical correlator. The output of this correlator consists of two autocorrelation peaks along with a strong dc. Out of these three terms, our interest is in capturing only one of the correlation peaks, while discarding the other correlation peak and strong dc. For capturing only one of the correlation peaks, we multiplied a chirp function with the rotation-invariant maximum average correlation height filter. The product function, that is basically a multiplied product of the input scene’s Fourier spectrum and the chirp-encoded filter, is inverse Fourier transformed to obtain the correlation peaks. Due to chirp encoding, the correlation signals are focused in three different planes. Thus, placing our peak capturing CCD camera at a particular plane we can capture only one autocorrelation peak. Results with almost similar tank images having different energy values have also been shown

Vehicular shape-based objects classification using Fourierdescriptor technique

484-495This paper reports classification of vehicular shape-based objects using Fourier descriptor (FD) technique. Retrieval andclassification of different types of shapes was done for closest match, comparing set of feature vectors of query object to eachobject of every class. Centroid distance based shape signatures were used for derivation of feature vectors. Euclidean distance wascalculated as a similarity measure parameter for shape classification. Classification of noisy objects was carried out using FDtechnique. FD performs better than wavelet descriptor (WD) technique