Nonlinear optical security system based on a joint transform correlator in the Fresnel domain

Abstract

A new optical security system for image encryption based on a nonlinear joint transform correlator (JTC) in the Fresnel domain (FrD) is proposed. The proposal of the encryption process is a lensless optical system that produces a real encrypted image and is a simplified version of some previous JTC-based encryption systems. We use a random complex mask as the key in the nonlinear system for the purpose of increasing the security of the encrypted image. In order to retrieve the primary image in the decryption process, a nonlinear operation has to be introduced in the encrypted function. The optical decryption process is implemented through the Fresnel transform and the fractional Fourier transform. The security system proposed in this paper preserves the shift-invariance property of the JTC-based encryption system in the Fourier domain, with respect to the lateral displacement of the key random mask in the decryption process. This system shows an improved resistance to chosen-plaintext and known-plaintext attacks, as they have been proposed in the cryptanalysis of the JTC encrypting system. Numerical simulations show the validity of this new optical security system.

Generalized formulation of an encryption system based on a joint transform correlator and fractional Fourier transform

“…Finally, we propose some guidelines in order to increase the security of the JTCbased encryption system against the CPA [26], and KPA [27]. The nonlinear operation introduced in the JFPS already improves the security of the encryption system against the CPA, just as it was proved in [14,16]. To increase the security of the encryption system against KPA, we recommend to use different probability density functions (not only the uniform distribution) for the random code functions corresponding to the RPM h(x) [14,16].…”

“…To increase the security of the encryption system against KPA, we recommend to use different probability density functions (not only the uniform distribution) for the random code functions corresponding to the RPM h(x) [14,16]. A random complex mask (RCM) was utilized as key for the encryptiondecryption system presented in [16]. This RCM can be used to further improve the resistance of the JTC-based encryption in the FrFD against KPA [16].…”

Photon-counting multifactor optical encryption and authentication

“…From these pieces of information the attacker may recover crucial information of the security system such as the hidden decryption key. For the interested reader, the security flaws of the DRPE are analysed elsewhere ( [15][16][17] for a 4 f -processor, [39][40][13][14] for the JTC architecture).…”

“…Most of the optical security systems usually deal with a single primary image (for instance, an object, a plaintext, a signature, a biometric signal) as authenticator [2][3][4][5][6][7][10][11][12][13][14][18][19][20][21][22][23]. Some approaches permit to store multiple primary images, either in an optical memory [9] or in a single encrypted distribution [24][25][26][27], with the purpose of sequential and independent one-by-one decryption.…”

Optical image encryption technique based on deterministic phase masks

“…This is done by setting two random phase masks in the input and the Fourier planes. Since the publication of this method, the DRPE scheme has been applied in different domains, such as fractional Fourier transform (FRT) 9,10 , Fresnel transform (FrT) 11,12,13 , gyrator transform (GT) 14,15 , quaternion Fourier transform 16 , diffractive imaging 17 , dual fractional Fourier-wavelet 18 , fractional Mellin 19 , and Hartley transform 20 . Nevertheless, it has been demonstrated that DRPE scheme is vulnerable to some type of attacks 21,22,23 and due to its high shift sensitivity, it requires high alignment accuracy in the spatial domain systems.…”