Abstract: The quick response (QR) code was designed for storage information and high-speed reading applications. QR codes are used to create a link between the real world products (tagged with the QR code) and the Internet. A new rich QR code is proposed that has two storage levels: a public level and a private level. The public level can be read by any QR code reading application, while the private level is constructed by replacing the black modules by specific textured patterns. These patterns, do not introduce disruption in the standard reading process and always perceived as black modules by any QR code reader. Thus the private level is invisible to standard QR code readers. It can also be used for document authentication. It consists of information encoded using q-ary code with an error correction capacity which helps to increase the storage capacity of the QR code and to determine the original document from a copy. The sensitivity of the used patterns to the print-and-scan (P&S) process represents this authentication. The pattern recognition method can be used both in a private message sharing and in an authentication scenario. The storage capacity can be notably enhanced by increasing the code alphabet q or by increasing the textured pattern size.

Keywords: Quick Response (QR), two-storage level, Message Sharing, Document Authentication.