Physical unclonable functions generated through chemical methods for anti-counterfeiting

The counterfeiting of goods has important economic implications and is also a threat to health and security. Incorporating anti-counterfeiting tags with physical unclonable functions (PUFs) into products is a promising solution for their authentication. PUFs are unique random physical patterns of taggants that cannot be copied and must be fabricated by a stochastic process that affords a large number of robust PUF tags. A PUF tag has a physical pattern that, if read with an appropriate analytical tool, can be recorded and stored. The PUF tag is then the ‘key’, whereas the stored pattern is the ‘lock’. This combination forms PUF keys that provide unbreakable encryption and combat counterfeiting. The stochastic assembly of physical patterns made from taggants exhibiting particular molecular properties is thus an excellent approach to designing new PUF keys. The counterfeiting of goods has economic implications and is a threat to health and security. One promising solution for product authentication is the incorporation of physical unclonable functions. This Review delineates how stochastic chemical processes can afford unique anti-counterfeiting tags that cannot be reproduced.