A Time-Dependent Fluorescent Hydrogel for "Time-Lock" Information Encryption

Information encryption has become increasingly important in recent years; however, information encryption materials, especially those encrypting on a time scale, are still in fancy. Herein, a "time-lock" information encryption material is developed based on a time-dependent fluorescent hydrogel. The fluorescence color of this hydrogel can be regulated between green and yellow, with distinctive changes in intensity, on a time scale by controlling the concentration of urea/urease and HCl. By taking advantage of this feature, "time-locked" information can be encoded. Such information self-erases with time, and moreover, fake or even opposing information is generated during this process. The correct information can only be recognized at a specified time, i.e., using a "time-key" to decrypt the information. This time-dependent feature endows the material with a higher level of security and provides new insight for information encryption.