Multiple-image encryption based on optical wavelet transform and multichannel fractional Fourier transform

• It is the multi-image encryption using multichannel FrFT and wavelets together which is reported for the first time.
• Multi-image can be realized and the keys can be special for each image.
• The number of encrypted images increases. The problem of insufficient capacity is solved better, which increases variability and flexibility of scheme.
• Multi-user authentication can be realized easily in the scheme.
• The scheme can resist known-plaintext attack effectively.

A multiple-image encryption scheme based on the optical wavelet transform (OWT) and the multichannel fractional Fourier transform (MFrFT) is proposed. The scheme can make full use of multi-resolution decomposition of wavelet transform (WT) and multichannel processing of MFrFT. The mentioned properties can achieve the encryption of multi-image and the encryption of single image. When encryption finished, each image gets its own fractional order and independent keys. Analysis of encrypted effects has been completed. Furthermore, the influence of WT type and order are analyzed, and the application and analysis of MFrFT are accomplished as well. Numerical simulation verifies the feasibility of the scheme and shows that the problem of insufficient capacity is better solved, and the flexibility of scheme increases. A simple opto-electronic mixed device to realize the scheme is proposed.