Physical Unclonable Functions in Integrated Circuit Chip Packaging for Security

Abstract

In the invention described, magnetic field characteristics of randomly placed magnetized particles are exploited by using the magnetic field fluctuations produced by the particles as measured by a sensor. The magnetized particles generate a complex magnetic field near the surface of an integrated circuit chip that can be used as a “fingerprint.” The positioning and orientation of the magnetized particles is an uncontrolled process, and thus the interaction between the sensor and the particles is complex. The randomness of the magnetic field magnitude and direction near the surface of the material containing the magnetic particles can be used to obtain a unique identifier for an item such as an integrated circuit chip carrying the PUF.

What is claimed is: 
     
         1 . A system comprising:
 a substrate;   a plurality of pre-magnetized particles that have random orientations of magnetization and are randomly dispersed in the substrate;   an external magneto-resistive sensor, wherein a magnetic field profile is measured along a defined non-linear path by relative movement of the sensor and the substrate; and an integrated circuit chip.   
     
     
         2 . The system of  claim 1 , further comprising a non-volatile memory on the integrated circuit chip, wherein the non-volatile memory contains magnetic field profile data measured from the pre-magnetized particles. 
     
     
         3 . The system of  claim 1 , wherein the pre-magnetized particles contain neodymium and iron and boron. 
     
     
         4 . The system of  claim 1 , wherein the pre-magnetized particles contain samarium and cobalt. 
     
     
         5 . The system of  claim 1 , wherein the average particle size diameter of the pre-magnetized particles is greater than 0.1 mm. 
     
     
         6 . The system of  claim 1 , wherein the average particle size diameter of the pre-magnetized particles is greater than 0.001 mm.