An asymmetric single-channel color image encryption based on Hartley transform and gyrator transform

• A single-channel image encryption using Hartley- and gyrator transform is proposed.
• A single-channel is obtained by multiplying the three-Hartley transformed channels.
• The decryption keys, RPM, and order of gyrator transform serve as main keys.
• The optoelectronic encryption and decryption designs are presented.
• Numerical simulations demonstrate the performance and security of the scheme.

A novel asymmetric single-channel color image encryption using Hartley transform and gyrator transform is proposed. A color image is segregated into R, G, and B channels and then each channel is independently Hartley transformed. The three transformed channels are multiplied and then phase- and amplitude truncated to obtain first encrypted image and first decryption key. The encoded image is modulated with a conjugate of random phase mask. The modulated image is gyrator transformed and then phase- and amplitude truncated to get second encrypted image and second decryption key. The asymmetric (decryption) keys, random phase mask, and transformation angle of gyrator transform serve as main keys. The optoelectronic encryption and decryption systems are suggested. Numerical simulation results have been demonstrated to verify the performance and security of the proposed security system.