Fig. 1. Comparison of spatial and TGI experimental setups. (a) Spatial setup; (b) temporal setup.

Fig. 2. Information encryption schematic based on TGI.

Fig. 3. CDMA schematic diagram.

Fig. 4. Schematic diagram of CDMA-TGI.

Fig. 5. (a) Plaintext; (b) chip sequences; (c) combined information; (d) ciphertext; (e) reconstructed combined information; and (f) reconstructed plaintext.

Fig. 6. CC of reconstruction effect between the CS algorithm and the correlation algorithm.

Fig. 7. Chosen plaintext attack crack results of TGI. (a) Plaintext and (b) crack result of fixed temporal patterns.

Fig. 8. Chosen plaintext attack crack results of CDMA-TGI. (a) Plaintext; (b) crack result of fixed temporal patterns; and (c) crack result of random temporal patterns.

Fig. 9. CC between the plaintext and reconstruction information under different noise intensities.

Fig. 10. CC between the plaintext and reconstruction information under different loss rates.

Fig. 11. CC between the plaintext and reconstruction information under different numbers of receivers.

Fig. 12. Experimental schematic diagram. (a) Encryption process; (b) decryption process; and (c) schematic diagram of the optical experimental device.

Fig. 13. Experimental results. (a) Reconstructed data with correct modulation information. (b) Reconstructed plaintext with correct data. (c) Reconstructed data with wrong modulation information. (d) Reconstructed plaintext with wrong data.

Fig. 14. (a) CCs of different loss rates in the experiment and (b) CCs of different numbers of receivers in the experiment.