Method of attack on schemes of optical encryption with spatially incoherent illumination

Optical encryption with spatially incoherent illumination does not suffer from speckle noise and does not require holographic registration setup like coherent techniques do. However, as only light intensity distribution is considered, mean value of image to be encrypted is always above zero which leads to intensive zero spatial frequency peak in image spectrum. Consequently, in case of spatially incoherent illumination, image spectrum, as well as an encryption key spectrum, cannot be white. This can be used to crack encryption system. If encryption key is very sparse, encrypted image might contain parts or even whole unhidden original image. In case of denser keys, original image boundaries still might be partially visible. This will not provide correct decryption key, but will allow to significantly narrow the search for one. Therefore, in this paper new attack method on schemes of optical encryption with spatially incoherent illumination is presented. Method is based on detection of original image boundaries in the encrypted image. Because encryption is accomplished via optical convolution of original image with encryption key, encryption key can be found if original image is known. In proposed method, in place of original image (which is unknown to the attacker) we use random matrices. Reconstructed in this way keys are extremely noisy even in case of simplest keys, but after binarization they provide areas of encryption key points possible locations. In case of simplest keys proposed method allows to acquire correct key. In case of complex keys it allows to narrow the search for one. Results of numerical experiments on breaking the system of optical encryption with spatially incoherent illumination are presented.

[1]  John T. Sheridan,et al.  Random phase and jigsaw encryption in the Fresnel domain , 2004 .

[2]  Bo Wang,et al.  Optical stream-cipher-like system for image encryption based on Michelson interferometer. , 2011, Optics express.

[3]  Qiong Gong,et al.  Optical information encryption based on incoherent superposition with the help of the QR code , 2014 .

[4]  Bahram Javidi,et al.  Fault tolerance properties of a double phase encoding encryption technique , 1997 .

[5]  Nikolay N. Evtikhiev,et al.  Variants of minimum correlation energy filters: comparative study , 2012, Defense + Commercial Sensing.

[6]  P. Cheremkhin,et al.  QR code optical encryption using spatially incoherent illumination , 2017 .

[7]  Pavel A. Cheremkhin,et al.  Generation of keys for image optical encryption in spatially incoherent light aimed at reduction of image decryption error , 2014, Photonics Europe.

[8]  Nikolay N. Evtikhiev,et al.  Method of optical image coding by time integration , 2012, Photonics Europe.

[9]  Edward R. Dowski,et al.  A New Paradigm for Imaging Systems , 2002, PICS.

[10]  Pavel A. Cheremkhin,et al.  Modeling of digital information optical encryption system with spatially incoherent illumination , 2015, SPIE Security + Defence.

[11]  B Javidi,et al.  Error-reduction techniques and error analysis for fully phase- and amplitude-based encryption. , 2000, Applied optics.

[12]  Naveen K. Nishchal,et al.  Fresnel domain nonlinear optical image encryption scheme based on Gerchberg-Saxton phase-retrieval algorithm. , 2014, Applied optics.

[13]  Rong Li,et al.  Optical image encryption and hiding based on a modified Mach-Zehnder interferometer. , 2014, Optics express.

[14]  John T. Sheridan,et al.  A review of optical image encryption techniques , 2014 .

[15]  Xudong Chen,et al.  Optical image encryption based on diffractive imaging. , 2010, Optics letters.

[16]  Vladislav G. Rodin,et al.  Input scene restoration in pattern recognition correlator based on digital photo camera , 2007, SPIE Defense + Commercial Sensing.

[18]  Nikolay N. Evtikhiev,et al.  Projection multiplex recording of computer-synthesised one-dimensional Fourier holograms for holographic memory systems: mathematical and experimental modelling , 2015 .

[19]  G. Unnikrishnan,et al.  Optical encryption by double-random phase encoding in the fractional Fourier domain. , 2000, Optics letters.

[20]  Roberto Torroba,et al.  Experimental scrambling and noise reduction applied to the optical encryption of QR codes. , 2014, Optics express.

[21]  B Javidi,et al.  Optical image encryption based on input plane and Fourier plane random encoding. , 1995, Optics letters.

[22]  Yan Zhang,et al.  Optical image encryption with spatially incoherent illumination. , 2013, Optics letters.

[23]  Pavel A. Cheremkhin,et al.  Optical encryption in spatially-incoherent light using two LC SLMs for both information input and encryption element imaging , 2014, Security and Defence.