Digital Image Exchange using a No-key(s) Protocol with Phase-only Encryption

This paper considers an algorithm for transferring a digital image over an open network using a No-key(s) Protocol or Three-Way Pass and phase-only encryption/decryption. After providing a short study on the theoretical background to the method, an algorithm is presented on a step-by-step basis. Cryptanalysis is undertaken for the three intercept and single intercept cases, when it is assumed that the encrypted data is intercepted in its entirety for each pass or for any single pass, respectively. The algorithm focuses on the exchange of a JPEG image although in principle, the approach is independent of the format of the image file that is used. Prototype MATLAB functions are provided for the validation of the approach and for further development by interested readers.