Counterfeit Detection by Smartphone Using Double-Encoded Two-Dimensional Code

We propose a counterfeit detection system that uses a double-coding procedure to encode two-dimensional code. The system uses ordinary black ink, which absorbs infrared rays, and special black ink, which transmits infrared rays. Because special black is copied as ordinary black when replicated by a copying machine, the double-encoded data is lost, thereby enabling the item identified by the code to be identified as a counterfeit. The double-coded two-dimensional code is decoded by comparing the images obtained under white light and infrared radiation. If the data to be double-coded is encrypted, the counterfeiter cannot forge the double-coded two-dimensional code. Duplication can also be detected by using the data to be double-coded as encrypted data of the serial number.