A physical unclonable function, or PUF, is a "digital fingerprint" that serves as a unique identity for a semiconductor device such as a microprocessor. PUFs are based on physical variations which occur naturally during semiconductor manufacturing, and which make it possible to differentiate between otherwise identical semiconductors. PUFs are usually utilized in cryptography. A physical unclonable function (sometimes also called physically unclonable function) is a physical entity that is embodied in a physical structure. Today, PUFs are usually implemented in integrated circuits and are typically used in applications with high security requirements.

The chip's unique birthmark iUnique technology is based on the physical non-cloning technology PUF, which uses the random characteristics of each chip to generate a random key or security ID, which is the unique "fetal birthmark" unique to each chip, and solves the root of trust of the system.