Abstract: Two-dimensional code authentication based on anti-counterfeiting techniques has received continuously increasing concerns from academia and industry. However, the existing anti-counterfeit scheme based on two-dimensional code has some drawbacks such as poor identification experience, high cost, and inadequate anti-counterfeit ability, and the anti-counterfeiting procedures take place only after sale. Therefore, a novel anti-counterfeiting pattern based on multilevel blocks with encryption and scrambling is proposed. Firstly, the first level expansion is performed to replace every pixel in the original binary message image by a pixel block with a specific size. Secondly, the obtained image is encrypted based on Logistic chaotic sequence. Thirdly, the image is scrambled by Arnold transformation. Finally, the second level expansion is performed to replace every pixel in the generated image by a pixel block with a specific size and gray value, so as to form a complex and chaotic anti-counterfeiting pattern. The printed image is decoded to obtain the readability of the secret message, in order to distinguish whether the pattern is printed at the first time or the second time. Experimental results show that the proposed anti-counterfeiting pattern has good confidentiality, good ability to distinguish the commonly used forgery means, smaller physical size, and relatively convenient identification procedure.

Key words: two-dimensional code, anti-counterfeiting printing, information hiding, anti-copying pattern, semi-fragile