Metasurface‐Based Cryptography: From Multi‐Dimensional Manipulation to Algorithmic Assistance

Metasurfaces are artificial two‐dimensional photonic structures at the subwavelength scale, which enable flexible manipulation of electromagnetic waves, thus providing a powerful platform for information encryption. This review presents current encryption technologies based on diverse structured metasurfaces, with two major focuses: multi‐dimensional manipulation and algorithmic assistance. For multi‐dimensional manipulation, key strategies are summarized, including multi‐optical parameter multiplexing and synergy, holography combined with structural color or quantum entanglement, and dynamic tunability enabled by materials or external fields. These strategies support high‐capacity, high‐security information storage and transmission. For algorithmic assistance, the deep integration of various algorithms with the metasurface is discussed. The roles of such integration in building multi‐level and anti‐attack hybrid cryptosystems are analyzed. Finally, the challenges faced by metasurface encryption technology in terms of integration, intelligence, quantization, standardization, and system deployment are prospected, and future development trends are outlined.