Anti-counterfeiting patterns encrypted with multi-mode luminescent nanotaggants.

Anti-counterfeiting patterns are encrypted with nanotaggants that are selectively excited at distinct wavelengths. Decryption is realized by examining the temporal color or graphic responses of the pattern under various illumination wavelengths. The covert color and graphic codes that are designable through control of the nanotaggant composition are expected to provide high-level security.