Error-reduction techniques and error analysis for fully phase- and amplitude-based encryption

The performance of fully phase- and amplitude-based encryption processors i s analyzed. The effects of noise perturbations on the encrypted information are considered. A thresholding method of decryption that further reduces t he mean-squared error (MSE) for the fully phase- and amplitude-based encryp tion processes is provided. The proposed thresholding scheme significantly improves the performance of fully phase- and amplitude-based encryption, as measured by the MSE metric. We obtain analytical MSE bounds when threshold ing is used for both decryption methods, and we also present computer-simul ation results. These results show that the fully phase-based method is more robust. We also give a formal proof of a conjecture about the decrypted di stribution of distorted encrypted information. This allows the analytical b ounds of the MSE to be extended to more general non-Gaussian, nonadditive, nonstationary distortions. Computer simulations support this extension. (C) 2000 Optical Society of America OCIS codes: 100.0100, 070.0070, 110.4280, 070.4560, 110.3000.