ABSTRACT False knowledge is more misleading than no information, and the rising threats from counterfeitors demand advanced strategies of secure, multilayered encryption. The fluorescence‐based routine systems have become recurrent, often requiring complicated synthesis and UV light for decoding. We have countered the common notion that novel applications need newer molecules by employing conventional molecules in unconventional ways. Motivated by nature, we implemented stimuli‐responsive organic dyes to develop color‐coded encryption—simple, harmless, and UV‐free alternatives that preserve crucial security features. pH‐ or redox‐responsive dyes were purposely selected so that time‐dependent color changes can be displayed under chemically triggered nonequilibrium conditions. This feature was exploited in designing time‐gated, multidimensional, diverse color codes. An alternative decryption method was demonstrated via smart windows—stimuli‐sensitive barriers that regulated access across parallel time scales managed by independent triggers. Our strategy affords dual time‐locked color codes with hierarchical security operated through orthogonal stimuli, achieving complex encryption with simple, synthesis‐free decoding. A highly accurate indigenous decoding strategy is successfully demonstrated.
Das et al. (2026) studied this question.