Fig. 7: High-security encryption via \({\mathcal{M}}\)-multiplexed holography.

a Design of the \({\mathcal{M}}\)-multiplexed hologram. Binary patterns ''0” and ''1” are encoded into distinct operator pathways.The hologram is binarized using a modified off-axis encoding method and fabricated inside glass via femtosecond laser writing. b Experimental reconstruction. Correct parameters reconstruct “0” and “1'', while deviations yield no discernible patterns. c Plaintext-to-ciphertext conversion. Plaintext “SJTU” is converted to Morse code (“0” for dots, “1” for dashes) and mapped to sequential operator pathways. d Synchronized keychain generation. Three parameter keys (TC, n, d) are generated, each strictly aligned with the binary sequence. e Noise obfuscation. Random values are injected into the keychains to disrupt deterministic parameter correlations while preserving valid sequence alignment. f Decryption workflow. User2 applies obfuscated keychains to reconstruct the hologram, filters noise via intensity thresholding, and decodes the Morse sequence to recover “SJTU''