Fig. 4: Plaintext protection with double-secure scheme and multichannel encryption.
From: High-security learning-based optical encryption assisted by disordered metasurface
a, b Attack analysis regarding Input 2. Decryption with correct ciphertext (i.e., Input 1: speckles) by varying Input 2 with a correct QR code (Row I), a uniform pattern (Row II), and a random binary pattern (Row III) for a qualitative demonstration and b the statistics, quantifying the PCC and SSIM between the plaintext and decrypted images for Rows I–III. PCC Pearson’s correlation coefficient, SSIM structure similarity index. The metrics for both “Correct” and “Uniform” are averaged over 2000 samples, and metrics for the ‘Random’ group is the average of 1,000,000 randomly generated binary-amplitude attacks. c Cross-validation for the decryption by inputting speckles with seven different polarization states (i.e., P(i)-speckles, i = 1,2,3,4,5,6,7) into DMNet with seven different states (i.e., P(i)-DMNet, i = 1,2,3,4,5,6,7). (d) Averaged decryption PCC corresponding to the cross-validation arrangement in (c) and each is averaged over 2000 samples. QR quick response, PCC Pearson’s correlation coefficient, SSIM structure similarity.
