Copy detection pattern

Authentication is made by scanning the printed CDP using an image scanner or mobile phone camera.

[5] A CDP can also be inserted into a 2D barcode to facilitate smartphone authentication and to connect with traceability data.

They are motivated by the need for security features that can be originated, managed and transferred digitally, and that are machine readable.

[1] Contrarily to many traditional security printing techniques, CDPs do not rely on Security by Obscurity,[8] as the algorithm for generating CDPs can be public as long as the key used to generate it or the digital CDP is not revealed.

[2] While they have been cited as a "powerful tool to detect copies",[10] it is noted however that CDPs "require an extensive knowledge of printing technologies"[11] because the printing process introduces variation that is foundational to copy detection.The theoretical and practical assessment of the security level of CDPs, in other words the detector's ability to detect counterfeit attempts, is an ongoing area of research: CDPs are used for different physical item authentication applications: The EURion constellation and digital watermarks are inserted into banknotes to be detected by scanners, photocopiers and image processing software.