Based on Laser-induced Breakdown Spectroscopy and Encryption and Decryption of Printer Chinese Information

This paper proposes a method for encrypting Chinese information by writing it on printing paper using colorless steganographic ink, with the printer’s Chinese information serving as pseudo-information. The encrypted information cannot be visualized with the naked eye due to its nature. To achieve spatial resolution of the characteristic elements in the encrypted Chinese message and enable decryption, the experiment employed laser-induced breakdown spectroscopy (LIBS). This paper covers various aspects, including the process of LIBS spectral generation, calibration and spatial resolution of elements, as well as the experimental procedures such as sample preparation, data processing, analysis, and discussion. To address the accuracy of the experimental instrument and the size of the ablation pits, the authors selected different acquisition spacings and numbers to perform elemental calibration and spatial resolution in the experiment. The effect of resolution size on the imaging effect was verified by comparing the acquisition spacing and the number of acquisitions, and by generating a contour map. With the advantage of LIBS’ ability to detect multiple elements simultaneously, the authors separately achieved spatial resolution of the pseudo-information and encrypted information within the same sample. By analyzing comparison graphs of spectral signal intensities for all elements in the unprocessed printing paper, the authors concluded that Zn I was the characterizing element used for encrypting and decrypting messages in the experiment, while Cu I was the characterizing element for pseudo-messages. High spatial resolution was employed to effectively discriminate between the encrypted and pseudo information. Ultimately, the objective of encryption and decryption was successfully achieved.