2-step Phase-shifting Digital Holographic Optical Encryption and Error Analysis

Abstract

We propose a new 2-step phase-shifting digital holographic optical encryption technique and analyze tolerance error for this cipher system. 2-step phase-shifting digital holograms are acquired by moving the PZT mirror with phase step of 0 or π/2 in the reference beam path of the Mach-Zehnder type interferometer. Digital hologram with the encrypted information is Fourier transform hologram and is recorded on CCD camera with 256 gray-level quantized intensities. The decryption performance of binary bit data and image data is analyzed by considering error factors. One of the most important errors is quantization error in detecting the digital hologram intensity on CCD. The more the number of quantization error pixels and the variation of gray-level increase, the more the number of error bits increases for decryption. Computer experiments show the results to be carried out encryption and decryption with the proposed method and the graph to analyze the tolerance of the quantization error in the system.

Dual Optical Encryption for Binary Data and Secret Key Using Phase-shifting Digital Holography

“…(6), the phase difference of object beam and reference beam and the magnitude are calculated as follows. [22] …”

“…In the previous papers [19,22], we described the encryption and decryption principle by using the 2-step phase-shifting digital holographic method.…”

“…[13][14][15][16] Recently, we have presented some papers on the optical encryption using the phase-shifting digital holographic method. [17][18][19][20][21][22] In this paper, we propose a dual optical encryption method for binary image data and secret key based on 2-step phaseshifting digital holography for a cryptographic system, and show the performance of the proposed system for dual cryptography. The encrypted Fourier transform hologram is obtained by phase-shifting a digital holographic technique from an optical setup based on a Mach-Zehnder type interferometer, which is a 256 gray level quantized digital hologram recorded by CCD.…”

Optical Image Split-encryption Based on Object Plane for Completely Removing the Silhouette Problem

“…So a gray-level error on CCD camera pixels can be generated due to a small intensity variation, which is the so-called quantization error [2]. If there is no error, the decryption equation expression should be like Eq.…”

“…Two random phase-only functions (POFs) are utilized in this method. The first POF improves the signal of a charge-coupled device (CCD), and the second POF is the encryption key in the system [2]. However, when the complex conjugate of the information obtained in the frequency domain is considered as the ciphertext, the decryption key must be identical to the second random POF so-called symmetric cryptography.…”