Unique identification and authentication of products

A method of product authentication, the method comprising:

• (a) applying or introducing an identification substance admixture comprising paramagnetic phases to/into a product or identifying the product comprising the identification substance admixture comprising paramagnetic phases, wherein the identification substance admixture has an electron spin resonance (ESR) fingerprint spectrum that permits unambiguous identification of the product;
• (b) recording the ESR fingerprint spectrum of the product;
• (c) generating and storing a digital representation of the ESR fingerprint spectrum;
• (d) measuring an ESR spectrum of a product to be authenticated and generating a digital representation of the ESR spectrum measured;
• and
• (e) verifying the product to be authenticated by comparing the digital representation of the ESR spectrum measured of the product to be authenticated with digital representations of stored ESR fingerprint spectra,
• wherein a verification of an authenticity of a multitude of measured ESR spectra is conducted in a common detection step, and
• wherein the common detection step uses zero-knowledge proof which enables an authentication of a calculation of a sum of multiple individual values without needing to disclose the individual values itself.