mohammed ahouzi - Academia.edu (original) (raw)

Papers by mohammed ahouzi

Optics Communications, 1994

An architecture based on a classical convergent correlator to obtain the pure phase correlation i... more An architecture based on a classical convergent correlator to obtain the pure phase correlation is proposed. The effects of the amplitude transmission of the filter and the effects of the quantization introduced by the CCD camera are studied in terms of correlation performance by computer simulation.

2016 15th Workshop on Information Optics (WIO), 2016

There is growing interest of the successful application of double random phase encoding in optica... more There is growing interest of the successful application of double random phase encoding in optical encryption techniques. Nevertheless, this method has some weaknesses such as the problem of optical axis alignment. A few modified schemes have been proposed in order to improve the misalignment but not for the DRPE. This paper addresses a simulated solution of DRPE scheme based on 4f optically system to improve the shift tolerance of the decrypting key by using deterministic phase masks instead of random phase masks. The main advantage of deterministic phase masks is the compact and tiny size of the keys and they are long enough so that an attacker cannot try any possible combinations. Initial feasibility studies have been undertaken and show a sufficient enhancement to axis alignment as compared to the conventional DRPE. We describe the principle of masks generation and present the simulations results which have been made to evaluate its performance in terms of data loss and shift of the decrypting key in the Fourier plane.

Optical Engineering, 2016

The double random phase encoding (DRPE) scheme, which is based on a 4f optical correlator system,... more The double random phase encoding (DRPE) scheme, which is based on a 4f optical correlator system, is considered as a reference for the optical encryption field. In this work, we propose a modification of the classical DRPE scheme based on the use of a novel class of structured phase masks, the deterministic phase masks. In particular, we propose to conduct the encryption process by using two deterministic phase masks, which are built from linear combinations of several sub-keys. For the decryption step, the input image is retrieved by using the complex conjugate of the deterministic phase masks, which were set in the encryption process. This new concept of structured masks gives rise to encryption-decryption keys which are smaller and more compact than those required in the classical DRPE. In addition, we show that our method significantly improves the tolerance of the DRPE method to shifts of the decrypting phase mask-when no shift is applied, it provides similar performance to the DRPE scheme in terms of encryption-decryption results-. This enhanced tolerance to the shift, which is proven by providing numerical simulation results for gray-scale and binary images, may relax the rigidity of an encryptiondecryption experimental implementation setup. To evaluate the effectiveness of the described method, the meansquare-error (MSE) and the peak signal-to-noise ratio (PSNR) between the input images and the recovered images are calculated. Different studies based on simulated data are also provided to highlight the suitability and robustness of the method when applied to image encryption-decryption processes.

… and Applications, 2009 …, 2009

... Nawfel AZAMI Institut National des Postes et Télécommunications Rabat, Morocco nawazami@inpt.... more ... Nawfel AZAMI Institut National des Postes et Télécommunications Rabat, Morocco nawazami@inpt.ac.ma ... Most current verification and identification systems are based on passwords which can be guessed, stolen or broken. ...

Optics Communications, 1994

An architecture based on a classical convergent correlator to obtain the pure phase correlation i... more An architecture based on a classical convergent correlator to obtain the pure phase correlation is proposed. The effects of the amplitude transmission of the filter and the effects of the quantization introduced by the CCD camera are studied in terms of correlation performance by computer simulation.

2016 15th Workshop on Information Optics (WIO), 2016

There is growing interest of the successful application of double random phase encoding in optica... more There is growing interest of the successful application of double random phase encoding in optical encryption techniques. Nevertheless, this method has some weaknesses such as the problem of optical axis alignment. A few modified schemes have been proposed in order to improve the misalignment but not for the DRPE. This paper addresses a simulated solution of DRPE scheme based on 4f optically system to improve the shift tolerance of the decrypting key by using deterministic phase masks instead of random phase masks. The main advantage of deterministic phase masks is the compact and tiny size of the keys and they are long enough so that an attacker cannot try any possible combinations. Initial feasibility studies have been undertaken and show a sufficient enhancement to axis alignment as compared to the conventional DRPE. We describe the principle of masks generation and present the simulations results which have been made to evaluate its performance in terms of data loss and shift of the decrypting key in the Fourier plane.

Optical Engineering, 2016

The double random phase encoding (DRPE) scheme, which is based on a 4f optical correlator system,... more The double random phase encoding (DRPE) scheme, which is based on a 4f optical correlator system, is considered as a reference for the optical encryption field. In this work, we propose a modification of the classical DRPE scheme based on the use of a novel class of structured phase masks, the deterministic phase masks. In particular, we propose to conduct the encryption process by using two deterministic phase masks, which are built from linear combinations of several sub-keys. For the decryption step, the input image is retrieved by using the complex conjugate of the deterministic phase masks, which were set in the encryption process. This new concept of structured masks gives rise to encryption-decryption keys which are smaller and more compact than those required in the classical DRPE. In addition, we show that our method significantly improves the tolerance of the DRPE method to shifts of the decrypting phase mask-when no shift is applied, it provides similar performance to the DRPE scheme in terms of encryption-decryption results-. This enhanced tolerance to the shift, which is proven by providing numerical simulation results for gray-scale and binary images, may relax the rigidity of an encryptiondecryption experimental implementation setup. To evaluate the effectiveness of the described method, the meansquare-error (MSE) and the peak signal-to-noise ratio (PSNR) between the input images and the recovered images are calculated. Different studies based on simulated data are also provided to highlight the suitability and robustness of the method when applied to image encryption-decryption processes.

… and Applications, 2009 …, 2009

... Nawfel AZAMI Institut National des Postes et Télécommunications Rabat, Morocco nawazami@inpt.... more ... Nawfel AZAMI Institut National des Postes et Télécommunications Rabat, Morocco nawazami@inpt.ac.ma ... Most current verification and identification systems are based on passwords which can be guessed, stolen or broken. ...