Optical image encryption based on a joint Fresnel transform correlator with double optical wedges

Area of Science:

• Optics
• Information Security
• Cryptography

Background:

• Traditional joint transform correlator (JTC) based optical cryptosystems face challenges with real-valued encrypted images and complex key generation.
• Existing JTC systems can suffer from noise during decryption, impacting image quality and security.

Purpose of the Study:

• To design a novel optical cryptosystem with enhanced security and improved decrypted image quality.
• To simplify the encryption process and overcome limitations of existing JTC-based systems.

Main Methods:

• Design of an optical cryptosystem utilizing a joint Fresnel transform correlator (JFTC) with double optical wedges.
• Implementation of a denoising process and selection of key parameters (half-central interval 'a' and encrypted image width 'w') for optimization.
• Introduction of a nonlinear encryption process involving division by the Fresnel transform power distribution of the key mask.

Main Results:

• The designed cryptosystem produces real-valued encrypted images, simplifying recording and transmission.
• Achieved a high correlation coefficient of 0.9819 between decrypted and original images after denoising and parameter selection.
• Demonstrated enhanced attack resistibility due to nonlinear encryption and an expanded key space via parameter 'a'.

Conclusions:

• The proposed JFTC-based optical cryptosystem offers significant advantages over traditional JTC systems, including simplified operation and superior decrypted image quality.
• The system provides enhanced security through nonlinear encryption and a larger key space, making it a promising advancement in optical cryptography.