Abstract: For efficient and accurate tracking of users in collusion,this paper puts forward a digital fingerprint coding algorithm based on the uniqueness of QR codes and chaotic scrambling binary image which can reduce the similarity between the fingerprint information.Experiments show that by setting the initial value and the coefficient of Logistic mapping,the fingerprint information plays an important role in encryption so as to improve the security of the fingerprint information;the correlation between illegal users and complicity QR code fingerprint images is higher than 80% (and the correlation for the users not involved is 70%~80%).The correlation is used to determine whether the user involves in complicity,thus effectively improving the precision of the tracking users in collusion.

Key words: digital fingerprinting;QR code;chaotic scrambling